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For the mechanism of decarboxylation reactions, all textbooks state that electrons move from the πC=O bond. However, the most electron-donating bond orbital in the carbonyl group is expected to be the lone pair(s) on the oxygen. Thus, orbital theory with delocalization from a lone pair might be more appropriate than delocalization from the πC=O orbital. We confirmed this idea by theoretical calculations. In the transition state of 2-substituted β-keto acids, a boat conformation is expected to result in the exclusive generation of (E)-enols. Normally, the decarboxylation reaction occurs in polar solvents, so the resulting enols should be transformed into the corresponding ketones by tautomerization. The use of heteroatoms to obtain enolate or enol ethers without tautomerization would offer a diastereoselective enol(ate) synthesis with regioselectivity because the C=C double bond would always be introduced between two carbonyl groups. After screening heteroatoms by theoretical calculations, we found that boron is suitable for this purpose. We confirmed our idea by theoretical calculations, offering a new boradecarboxylation reaction for the diastereo- and regioselective production of enolates.

Recently, we demonstrated that, contrary to the explanation in most textbooks on organic chemistry, the mechanism of the decarboxylation reaction can be more appropriately explained by the orbital theory, since the most electrondonating bond orbital, i.e., the highest occupied bond orbital, in a carbonyl group should be the lone pair on the oxygen, not the .pi.-bond orbital of the C=O bond. Thus, the electron moves from the lone pair to the .sigma.*-orbital of the OH bond, not from the .pi.-orbital of the carbonyl group. With this insight, we succeeded in developing the boradecarboxylation reaction. In our initial screening, the alkali metals were not so promising since they decomposed in TSs. However, the calculations were performed without considering solvation in the gas phase. We supposed that this was influenced by the strongly ionic character of the alkali metal ions. We reconsidered the calculations including those involv-ing the solvent molecules, dimethyl ether (DME) and THF.

In contrast to their carbon analogs, there are only a few reports on deprotonation from silanes. This is because the normal polarization of a Si-H bond is Si(delta+)-H(delta-), while that of a C-H bond is C(delta-)-H(delta+). From a bond orbital perspective, a sigma*CH orbital has greater expansion on hydrogen, while a sigma*SiH orbital has greater expansion on Si. Thus, the lone pair of a base mainly attacks hydrogen of a C-H bond for deprotonation, but adds to the silicon atom of a Si-H bond. Previous reports showed that the assistance of negative hyperconjugation between the lone pair of the silyl anion and sigma* orbitals on silyl substituent(s) or an intramolecular chelating group (a pincer ligand) is necessary for deprotonation from silanes. In fact, Kira et al. found that treatment of diphenylsilane with t-butyllithium or LDA resulted in nucleophilic substitution, not deprotonation, only to eliminate a hydride as a leaving group. Recently, we developed a silicon-homologation reaction by a deprotonation-nucleophilic substitution sequence. In that reaction, we assumed that dispro-portionation led to alkoxysilyllithium or a silenoid species generated in situ. We expected that a disproportionation approach could be applied to the deprotonation of monosilanes, such as diphenylsilane. Here we report the first successful approach to the deprotonation of monosilanes with no intramolecular chelation.

Cyclic orbital interaction, in which a series of orbitals interact with each other so as to make a monocyclic system, affords stabilization if the requirements of orbital phase continuity are satisfied. Initially, these requirements were derived from the consideration of a three-body system. Here I propose that these requirements can be easily derived by considering FMO theory.

Cyclic orbital interaction, in which a series of orbitals interact with each other so as to make a monocyclic system, affords stabilization if the requirements of orbital phase continuity are satisfied. Initially, these requirements were derived from the consideration of a three-body system. Here I propose that these requirements can be easily derived by considering FMO theory.

For mechanism of decarboxylation reaction, all textbooks show that the electron moves from the piC=O bond. However, the most donating bond orbital in the carbonyl group should be the lone pair(s) on the oxygen. Thus, a picture of orbital theory with delocalization from a lone pair should be more appropriate than that from the piC=O orbital. We confirmed our idea by theoretical calculation. In the TS, if we use 2-substituted b-ketoacids, the boat-form conformation should result in exclusively preferred generation of E-enolates. Normally, decarboxylation reaction performs in polar solvent, so that the resulting enols should be transformed to the corresponding ketones by tautomerization. Suppose we use the heteroatoms to obtain the enolate or enol ethers without tautomerization, it would offer a diastereoselective enol(ate) synthesis with regioselectivity, since the C=C double bond should always be introduced between two carbonyl groups. After screening the heteroatoms by the theoretical calculations, we found that boron is suitable for this purpose. We confirmed our idea by theoretical calculations, offering a new boradecarboxylation reaction to produce enolates diastereoselecitively and regioselectively.

The orbital phase refers to the relationship between orbitals that originates from their wave character. We show here that the orbital phase essentially determines the diastereoselectivity of the following three organic reactions. 1) Torquoselectivity of the electrocyclicring-opening reaction of 3-substituted cyclobutenes; 2) Contradictory torquoselectivity of the retro-Nazarov reaction; 3) Diastereoselectivity in electrophilic addition to substituted ethylenes.

Goodenough-Kanamori-Anderson rules (GKA rules) in superexchange interaction discriminate the magnetic properties of two magnetic metal ions bridged with an anion. We propose here that the GKA rules can be explained in terms of the orbital phase continuity-discontinuity property of cyclic orbital interaction including direct metal-metal orbital interaction.

To address the electronic effect in nucleophilic addition, we often use the Felkin-Anh model, in which the most sigma-electron-withdrawing group (.sigma.EWG) at the a-position of the carbonyl should be located anti to the nucleophile approach. The diastereoselectivity is often explained by the antiperiplanar effect of the .sigma.EWG. Reetz and Frenking reported that the FMO, the LUMO in the a-substituted ketone, has greater expansion anti the .sigma.EWG. Thus, the FMO theory can also apply to this diastereoselectivity. However, there is still no explanation for why the LUMO has greater expansion anti to the .sigma.EWG and toward the nucleophile approach with this conformation, as is suggested by the FMO theory. We show here that the phase-continuous cyclic orbital interaction among nNu:--.pi.*C=O-.sigma.*C-A/vic-.sigma.*CC/gem- controls the diastereoselectivity, which is confirmed with theoretical calculations and the bond model analysis using a conformationally-fixed bicyclic molecule, 2,3-bis(trifluoromethyl)bicyclo[2.2.1]heptan-7-one 1, as a model.

To address the electronic effect in nucleophilic addition, we often use the Felkin-Anh model, in which the most s-electron-withdrawing group (sEWG) at the a-position of the carbonyl should be located anti to the nucleophile approach. The diastereoselectivity is often explained by the antiperiplanar effect of the sEWG. Reetz and Frenking reported that the FMO, the LUMO in the a-substituted ketone, has greater expansion anti the sEWG. Thus, the FMO theory can also apply to this diastereoselectivity. However, there is still no explanation for why the LUMO has greater expansion anti to the sEWG and toward the nucleophile approach with this conformation, as is suggested by the FMO theory. We show here that the phase-continuous cyclic orbital interaction among nNu:--p*C=O-s*C-A/vic-s*CC/gem- controls the diastereoselectivity, which is confirmed with theoretical calculations and the bond model analysis using a conformationally-fixed bicyclic molecule, 2,3-bis(trifluoromethyl)bicyclo[2.2.1]heptan-7-one 1, as a model.

Three major factors determine torquoselectivity, which is the diastereoselectivity in electrocyclic ring-opening reactions to produce E/Z-double bond(s). One is the interaction between the decomposing sCC bond and low-lying vacant orbital(s), such as a p*- or s*-orbital on the substituent, which promotes the reaction, resulting in inward rotation of the substituent. Second, for a substituent with a lone pair(s), repulsive interaction between the decomposing s-bond and the lone pair(s) hinders inward rotation, so that the products of outward rotation should be preferred. Finally, a more strongly donating s-electron-donating group (sEDG) rotates inwardly due to stabilization by phase-continuous cyclic orbital interaction. We compared the latter two interactions, repulsion between the lone pairs on the substituent and stabilization from phase-continuous cyclic orbital interaction, to determine which has a greater effect on the diastereoselectivity. We considered a series of model reactions with halogen substituents, and concluded that the diastereoselectivity is mainly controlled by cyclic orbital interaction.

Electrophilic attack to a double bond is often observed anti to the most electron-donating σ-bond at the α-position (hereafter, we refer to this as the extended anomeric effect). This preference is believed to result from the antiperiplanar effect between the bond that is formed between the double bond and the electrophilic reagent, and the donating vicinal σ-bond which is located on the substituent at the α-position. From an orbital viewpoint, however, it is still unclear why the approach of the electrophile anti to the substituent results in stabilization or why the frontier molecular orbital (FMO) deforms, expanding toward the reagent with this antiperiplanar interaction. We demonstrate here that cyclic orbital interaction including geminal bond participation plays an important role in the diastereoselectivity in electrophilic addition. We examined our idea using the electrophilic addition of chlorine to 3-substituted propenes as a model reaction. Our bond model approach should contribute to a better understanding of orbital mixing in FMO.

Recently we reported that 2,6-dithiaspiro[3.3]hepta ne 2,6-dioxide 1a exists as enantiomers at ambient temperature and is able to be resolved. Th is is because the lone pair(s) on the sulfur atom(s) are rich in s-character, which results in h igh barrier for flipping the conformation of the four-membered ring, i.e., racemization of the spiro framework of 1a. During the HPLC analysis, we noticed considerably strong absorption of UV at 210 nm. We expected that the absorbance comes from n-σ* excitation. The acute bond angle of C-S-C leads to high p-character of the C-S bond(s), which lowers the σ* orbital energy. We performed the TD-DFT calculations of a model, constrained dimethylsulfoxide (DMSO) and 1a . The strong UV absorption of 1a is reproduced with the TD-DFT calculation. However, there are two sulfoxide groups arranged with chiral position in 1a , we could expect that the circular dichroism (CD) spectra are observable by coupling of two sulfoxide groups. Th e TD-DFT calculation showed that the Cotton effects should appear in the observable UV r ange. We separated the enantiomers of 1a by HPLC equipped with a chiral stationary phase col umn. The enantiomers are subjected to the CD analysis. We determined the absolute configurat ion of 1a , comparing the calculation and the obtained spectra. This is the first report of the CD spectra of n-σ* excitation.

Recently we have shown that retro-Nazarov reactions are under the control of geminal bond participation. In retro-Nazarov reactions, electrocyclic ring-opening must occur in a conrotatory manner, so that a geminally 4,4-disubstituted substrate and cis -4,5-disubstituted substrate may exhibit the same torquoselectivity with a substituent effect. For amino-hydroxy substituted substrates, however, cis -5-amino-4-hydroxy substituted 9 was calculated preferentially to give E -amino- Z -hydroxy product Z - 12 , while geminally disubstituted 4-amino-4-hydroxy 11 was expected to predominantly afford Z -amino- E -hydroxy product E - 12 . We demonstrate here that this discrepancy in torquoselectivity can be explained in terms of geminal bond participation: in 9 , the most electron-donating σ-bond is σ CH geminal to the amino group, which should rotate inwardly. Thus, the amino group should rotate outward. On the other hand, the σ CN bond is more electron-donating than the σ CO bond, which results in inward rotation of the amino group in 11 .

We have designed a new axially chiral bis(sulfoxide) molecule with conformational rigidity: 2,6-dithiaspiro[3.3]heptane 2,6-dioxide 2a . This molecule has axial asymmetry due to two puckered thietane ring systems. The lone pairs on the sulfur show a strong s-character, which was expected to result in a high barrier to racemization, that is, inversion at the sulfur. We confirmed this prediction by calculations and experimentation. The lone pairs of the sulfur in 2a are sp 1.00 and the enthalpy of activation (Δ H ‡ ) for inversion is 47.5 kcal/mol (B3LYP/6-31G(d)). The 1 H NMR spectra of 2a showed two doublets and two doubled doublet peaks, which resulted from the rigidity of the four-membered ring frameworks without flipping. We separated the enantiomers of 2a by HPLC with a chiral stationary phase column to observe a set of complementary peaks. We also calculated the diselena- and ditellura congeners and confirmed that they also show axial chirality.

Torquoselectivities of electrocyclic ring-opening reactions have been proposed to be controlled by the participation of electron-donating σ-bonds (σ-EDB) geminal to the breaking σ-bond and/or vicinal electron-accepting σ-bonds (σ-EAB) or lone pair(s) of the substituent(s). We designed reactions in which the effects of the vicinal bonds should be significantly diminished by the cationic nature of the reactants. The calculated enthalpies of activation of the retro-Nazarov reactions of some 3-substituted cyclopentenyl cations show inward rotation of the geminal σ-EDB, which is consistent with the theory of geminal bond participation.

The diastereoselectivity of the [3,3]-rearrangement of 1,1-disubsstituted allyl carboxylates was studied. In this heteroatom-containing system, the transition state has a boat-like transition structure (TS) because of the participation of the lone pairs and the secondary orbital interaction. Although the TS for the [1,3]-rearrangement has a far higher barrier, it does not proceed in the usual antarafacial manner due to the cyclic orbital interaction among two lone pairs of the carboxylate and the allylic lumo. In conjunction with the geminal bond participation, delocalization to the σ-bond at the Z-position shows a bonding character in the transition state of the [3,3]-rearrangement. Therefore, we predicted that a more electron-withdrawing σ-bond prefers the Z-position in the product. We designed the 1,1-disubstituted substrates with trimethylsilyl and pentyl groups, and found that the trimethylsilyl group prefers the Z-position despite its steric bulkiness. We confirmed our prediction by experimentation. This Z-selectivity was improved when a trimethylgermyl group was used.

Molecular interactions of neonicotinoid insecticides with the nicotinic acetylcholine receptor have been mapped by chemical and structural neurobiology approaches, thereby encouraging the biorational design of novel nicotinic ligands. This investigation designs, prepares, and evaluates the target site potency of neonicotinoid analogues with various types of electronegative pharmacophores and subsequently predicts their molecular recognition in the ligand-binding pocket. The N-nitroimino (NNO2) neonicotinoid pharmacophore is systematically replaced by N-nitrosoimino (NNO), N-formylimino [NC(O)H], N-alkyl- and N-arylcarbonylimino [NC(O)R], and N-alkoxy- and N-aryloxycarbonylimino [NC(O)OR] variants. The NNO analogues essentially retain the binding affinity of the NNO2 compounds, while the isosteric NC(O)H congeners have diminished potency. The NC(O)R and NC(O)OR analogues, where R is methyl, trifluoromethyl, phenyl, or pyridin-3-yl, have moderate to high affinities. Orientation of the tip oxygen plays a critical role for binding of the NNO and NC(O)H pharmacophores, and the extended NC(O)R and NC(O)OR moieties are embraced by unique binding domains.

The pharmacophore of the neonicotinoid insecticide thiacloprid, cyanoiminothiazolidine, was modified to heterocycles such as imidazolidine, pyrrolidine and oxazolidine (the central ring hereafter). Their 6-chloro-3-pyridylmethyl or 5-chloro-3-thiazolylmethyl derivatives were examined for insecticidal activity against the American cockroach by injection and neuroblocking activity using the cockroach ganglion. The derivatives showed strong insecticidal activity with the minimum lethal dose (MLD) of about 10 nmol, which were however mostly weaker than the corresponding nitromethylene or nitroimine compounds. The activity was enhanced in the presence of synergists. The neuroblocking effect of cyanoimino compounds was at the micromolar level. Quantitative analysis for 23 variants of the key pharmacophore, constructed with the central ring conjugated to an NCN, CHNO 2 , or NNO 2 , showed that the neuroblocking potency is proportional to the Mulliken charge on the nitro oxygen atom or cyano nitrogen atom. The optimum log P value was evaluated as 1.19. The equation for the insecticidal- vs. the neuroblocking-potencies indicated that both potencies are related proportionally with each other when the other factors are the same.

Molecules that contain a double bond between hypervalent atoms were designed. They included monocyclic five-membered ring molecules [HCO2(FPn)2]- and bicyclic molecules [HCO2Pn]2 (Pn = Sb, Bi), whi...

The pharmacophore of the neonicotinoid insecticide imidacloprid, nitroiminoimidazolidine, was modified to heterocycles such as thiazolidine, pyrrolidine, dihydroimidazole, dihydrothiazole, and pyridone conjugated to nitroimine (=NNO2) or nitromethylene (=CHNO2). Their 6-chloro-3-pyridylmethyl or 5-chloro-3-thiazolylmethyl derivatives were examined for insecticidal activity against the American cockroach by injection and for neuroblocking activity using the cockroach ganglion. Most of the compounds having the neonicotinoidal pharmacophore exhibited insecticidal activity at the nanomolar level, which was enhanced in the presence of synergists, and high neuroblocking activity at the micromolar level. Quantitative analysis for the compounds showed that the neuroblocking potency is proportional both to the Mulliken charge on the nitro oxygen atom and to the partition coefficient log P value. The equation for the insecticidal versus neuroblocking potencies indicated that both potencies are related proportionally with each other when the other factors are the same.

We predicted that uncatalyzed Mukaiyama aldol reactions are under the control of the geminal bond participation. At the transition state of the model reaction, addition of CH 2 O and CH 2 CH(OSiH 3 ), the interbond energy IBE is negative between the σ-bonding orbital at the Z -position of the enolate terminal and π C O ∗ , and positive between that at the E -position and π C O ∗ . These results led us to predict that the electron-donating σ-bond at the Z -position enhances the reactivity. We calculated the enthalpies of activation of the reactions of a variety of the R-substituted silyl enolates and confirmed the prediction by showing that the reactivity of the Z -isomers relative to that of the E -isomers increases with the energy of the bonding orbital of the σ bond at the Z -position (the axial position at the transition state of the chair form). We demonstrate that the geminal bond participation is general not only to the pericyclic reactions but also to the aldol reaction, which is one of the most fundamental C–C bond forming reactions.

Introduction of a double bond into cyclic silanes lowers the ring strain by the cyclic delocalization of π-electrons through the hyperconjugation with the σ bonds, which is favored by the high π-orbital energy of the Si Si bond and the low σ*-orbital energy of the Si–H bonds. The π-relaxation of strains significantly occurs in the small rings. Unsaturated small silicon ring molecules are less strained than the saturated ones and the unsaturated carbon congeners. We calculated a series of polycyclic silicon molecules to confirm the π-relaxation and suggested that some unknown molecules could be prepared due to the low strain.

We applied the geminal bond participation theory to Alder ene reactions. The interaction between the σ-orbital at the Z -position of the double bond of propene and the π ∗ -orbital of ethylene was predicted to be bonding, while that at the E -position should be antibonding. This prediction was confirmed by the bond model analysis of the model compound. These results suggest that the reactivity could be enhanced by substituting a more electron-donating σ-bond at the Z -position. To examine our prediction, theoretical calculations were performed for the systematically substituted substrates. The prediction was confirmed except in the case where the inductive effect of oxygen could affect the reactivity. The same trend in reactivity was observed for formaldehyde as an enophile.

Disilanes bearing four carboxylate ligands have a trigonal bipyramidal geometry around each silicon atom with two bridging carboxylate ligands with the apical Si-O axes, which are parallel to each other, in the crystalline state, while such a structure is in equilibrium with a tetrahedral structure in solution.

We have designed a new axially chiral diphosphine that shows conformational rigidity: 2,6-diphosphaspiro[3.3]heptane 2a . This molecule has axial asymmetry due to puckering of the two phosphetane ring systems. Although its nitrogen congener 2,6-diazaspiro[3.3]heptane 1a is easily racemized, 2,6-diphosphaspiro[3.3]heptane 2a does not racemize at ambient temperature because the lone pairs on the phosphorus atoms have a strong s-character, which results in a high barrier to inversion at the phosphorus, that is, a high barrier to racemization. We also calculated the properties of the diarsa congener 3a and predicted that it also exhibits axial chirality and that it can be separated into enantiomers at ambient temperature.

Here we show that amides of bicyclic 7-azabicyclo[2.2.1]heptane are intrinsically nitrogen-pyramidal. Single-crystal X-ray diffraction structures of some relevant bicyclic amides, including the prototype N-benzoyl-7-azabicyclo[2.2.1]heptane, exhibited nitrogen-pyramidalization in the solid state. We evaluated the rotational barriers about the amide bonds of various N-benzoyl-7-azabicyclo[2.2.1]heptanes in solution. The observed reduction of the rotational barriers of the bicyclic amides, as compared with those of the monocyclic pyrrolidine amides, is consistent with a nitrogen-pyramidal structure of 7-azabicyclo[2.2.1]heptane amides in solution. A good correlation was found between the magnitudes of the rotational barrier of N-benzoyl-7-azabicyclo[2.2.1]heptanes bearing para-substituents on the benzoyl group and the Hammett's sigma(p)(+) constants, and this is consistent with the similarity of the solution structures. Calculations with the density functional theory reproduced the nitrogen-pyramidal structures of these bicyclic amides as energy minima. The calculated magnitudes of electron delocalization from the nitrogen nonbonding n(N) orbital to the carbonyl pi orbital of the amide group evaluated by application of the bond model theory correlated well with the rotational barriers of a variety of amides, including amides of 7-azabicyclo[2.2.1]heptane. The nonplanarity of the amide nitrogen of 7-azabicyclo[2.2.1]heptanes would be derived from nitrogen-pyramidalization due to the CNC angle strain and twisting of the amide bond due to the allylic strain.

We showed that imidoyl- and phosphaethenyl(alkali metals) would thermodynamically prefer the Z-configuration. The bond model analysis of the electronic structures showed that the Z-preference should originate from 1,2-metallobridging by the delocalization of lone pairs on N or P to vacant p-orbitals of the alkali metals and from the antiperiplanar effect of the delocalization from σ C—M to σ∗ N(P)—R 2 and from n N(P) to the C—R1. The Z-preference increases by more electron-withdrawing groups at the carbon atom of the double bond. However, substitution at the nitrogen/phosphorus results in E-preference because of 1,4-chelation of the lone pair of the substituents to alkali metals. Most of halogen derivatives were not stable and eliminate metal halides.

We applied the geminal bond participation theory to cheletropic reactions. The interaction between σ-orbital of the inner bond and the π*-orbital of the NN bond was predicted to be bonding, while that involving the outer bond should be antibonding. The difference in the bonding/antibonding character of these interactions is due to the cyclic orbital interaction between the π*-orbital of the NN bond and the geminal bonds at the reaction center, which is influenced by the phase continuity between the orbitals. This prediction was confirmed by the bond model analysis of model compound 1a. These results suggest that reactivity could be enhanced by substituting the inwardly rotating σ-bond by a more electron-donating one, i.e. inward rotation of a substituent with a more electropositive atom. Theoretical calculations were performed for systematically substituted substrates. The prediction was confirmed except in the case of 1g, which was affected by the inductive effect of oxygen. Silyl/methyl-substituted 1e was subjected to the bond model analysis to confirm that the preferred inward rotation of the silyl group of 1e results from the geminal bond participation and little affected by steric effects.

The eclipsed conformers of ClSiH2SiH2SiH2OH (1) and dl -ClSiH2(OH)SiHSiH(OH)SiH2Cl (2) are the most stable due to the attractive 1,4-hypercoordination by the nO and σ*SiCl orbital interaction. The eclipsed rotamer of ClSiH2(OH)2SiSi(OH)(SiH2Cl)2 (3) is the exclusive conformer stabilized by the threefold 1,4-hypercoordination.

The σ and π relaxation of ring strain by electron delocalization from bonds to bonds was investigated to understand or predict the strains of (CH2)2X, (NH)2X, and (SiH2)2X (X = SiH2, PH, S). The σ relaxation by the delocalization between the geminal ring bonds is found to be significant and general for these molecules as well as for the homoatomic molecules. Delocalization of the lone pair on the heteroatom to the neighboring σ bonds contributes to the π relaxation of ring strain in (CH2)2X and (SiH2)2X except for X = SiH2 but contributes little to that of (NH)2X. However, the cyclic delocalization of lone pairs is generally not significant except in (SiH2)2S.

Recently, the first heptacoordinate disilane [(MesCS 2 ) 2 MeSi] 2 1 was synthesized and shown to have a unique structure by X-ray analysis. Each of the silicon atoms is surrounded by three nonbonded thiobenzoylthio groups. We theoretically investigated the origins of the unusual geometry of 1 containing multiple hypercoordinations. The model compound [(HCS 2 ) 2 MeSi] 2 2a shows both the H-CSi-Si eclipsed conformation and the C-SiSi-C eclipsed conformation. The dihedral angle of H-CSi-Si is calculated to be 24.6° at the RHF/6-31G* level (25.7° at the RHF/LANL2DZ+p level). Each of the carbon atoms of the methyl groups is also surrounded by three nonbonded thioformylthio groups. After the bond model analyses, we found that hypercoordination to the saturated carbon atom is essential for this unique geometry, as confirmed by scrutinizing the X-ray data of 1 .

Ring strains are relaxed by the cyclic orbital interaction between a π-bond and the σ-bonds on the saturated atoms in the rings. An effective relaxation by the π–σ* interaction occurs in the three-, four-, and five-membered silicon rings. Cyclotrisilene 2b , cyclotetrasilene 4b , and cyclopentasilene 6b have lower strains than those of the parent saturated analogs. However, the stabilization is less significant for the hydrocarbons.

Structures and reactions of CH3OCH2M (M = Li, Na, K) were investigated in a theoretical manner. CH3OCH2M has the acute bond angle of ∠M-C-O due to a strong coordination of the oxygen to the alkali metals. The nucleophilic substitution reaction of the substrate CH3OCH2Li by the nucleophile CH3OCH2Li is more preferred than the carbene generation by α-elimination and a nucleophilic substitution of CH3OCH2Li by CH3Li. The resulting 2-methoxyethyllithium readily liberated lithium methoxide to afford ethylene, which added to the anion species to give an ethylated product. Among the CH3OCH2M (M = Li, Na, K), CH3OCH2K is the most nucleophilic, due to the high σC–K level, while CH3OCH2Li is the most nucleophilic because of the lowest σ*C–O level. This supports a previously proposed mechanism for the ethylation of indole derivatives by methyl ethers in the presence of BuLi - t-BuOK.

Complexation of dimethyl penta-2,3-dienedioates to tris[(R)-(1R*)-3-(2,2,3,3,4,4,4-heptafluoro-1-oxobutyl)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-onato-O,O‘]europium, (+)-Eu(hfc)3, enriched the (S)-isomer with high enantioselectivity. When a more bulky ester was used, although the enantioselectivity increased to >95% ee, considerable decomposition occurred. Among the available lanthanide shift reagents, only the europium reagent is effective in this transformation. The reaction involves interconversion of diastereomeric complexes, with enrichment of the preferred one. However, the observed decrease in the 1H NMR peaks might suggest that subsequent reconstruction or reordering the higher-order complex may occur in the reaction solution.

The cruising range of an electric vehicle (EV) can be greatly extended by a dynamic wireless charging system because the battery can be charged while the vehicle is moving. However, the investment in infrastructure can be enormous and has to be reduced to implement the system. This paper presents the design of a wireless power transfer system with road embedded transmitter coils to facilitate dynamic charging of EVs. A 30 cm by 1.6 m transmitter coil, which is relatively long compared with the 40-cmdiameter circular receiver coil, has been designed to reduce the cost of the transmitter circuit. A prototype transmitter coil has been embedded into a road for evaluation of its characteristics. The measured coupling coefficient of the transmitter and receiver coils is as small as 0.09 because of the asymmetry between the coils. Compensation circuits for the transmitter and receiver coils have been designed and optimized for such a small coupling coefficient condition. The designed dynamic charging system can transfer more than 1 kW of electric power with more than 90% efficiency. Five transmitter circuits have been embedded into a road surface for testing. Cement asphalt mortar was used to construct the road surface in this study to avoid damaging the transmitter coils by high temperature and high pressure during the construction work. The designed receiver circuit has been installed on a compact 2-seater EV. A demonstration was conducted to show that the retrofitted EV can successfully receive electric power transferred from the road.

Stereospecific annulation of hydroxy vinyl ethers in the presence of triflic anhydride and tertiary amines and its synthetic application are described. Each 1-hydroxy-2-oxabicyclo[n.4.0]alkane, 2-oxabicyclo[n.4.0]alk-1(6)-ene and 2-oxabicyclo[n.4.0]alk-1(6+n)-ene is stereoselectively synthesized from the same hydroxy vinyl ether depending on the choice of the reaction conditions (temperature, solvent and tertiaryamine). These compounds lead to polyfunctionalized cyclic compounds and some natural products. We propose that this annulation reaction proceeds through a pure SN2-like mechanism.

Relaxation of strain in small ring molecules is reviewed in terms of two mechanisms – σ-relaxation and π-relaxation. The σ-relaxation occurs in in-plane interaction of the ring σ bonds. Previously proposed σ-aromaticity and surface delocalization are briefly discussed. The geminal interaction theory for the σ-relaxation of ring strains is discussed and applied. The geminal interaction is less antibonding or more bonding with decrease in the bond angle, when the hybrid orbital has low s-character for the ring bonds or has an s-rich lone pair (lone pair effect). π-Relaxation of unsaturated ring molecules results from the cyclic delocalization of π electrons through the σ bonds on the saturated ring atoms. The two mechanisms of the σ- and π-relaxation are shown to be necessary for better understanding of ring strains.

Ion-driven permeation (IDP) behavior has been investigated for deuterium implanted into pure iron with an incident ion energy of 300 eV to 2.0 keV. A permeation spike was observed in the implantation into virgin or annealed membrane. A good linear relationship was observed between the permeation flux and the incident ion flux. The permeation ratio increased with increasing the temperature. It is deduced that the IDP process through pure iron was controlled by a recombination reaction on both sides of the membrane. The permeation flux decreased as the incident ion energy increased. The higher energy run, on the contrary, enhanced the permeation flux of the following runs with lower energies.

Mass and heat transfer mechanisms of cryogenic distillation columns were studied to determine the dependence of the HETP on parameters such as phase flow rates and flow condition within the columns. The mass and heat transfer rates were calculated on the basis of the laminar boundary layer theory (diffusion model) and the Chilton-Colburn analogy (analogy model). The results calculated by these models were compared with experimental observations and those by the stage model. The stage model gave the best fit with the experimental observations. However, some data were in agreement with the results by the diffusion and analogy models. For these data, the HETP differed from component to component. From the simulation results by the analogy model it was observed that the overall mass transfer rate was proportional to the vapor velocity within the column. The HETP was unchanged against the vapor velocity because of this relationship between mass transfer rate and vapor velocity.

An efficient and stereospecific ring formation from unsaturated alcohols, which in turn are prepared by regio- and stereospecific ring opening of acetals, is described

A novel method for the highly regioselective deprotonation of the indole alkyl substituents has been established by the particular sequence of base treatments. This success may be due to the aromatic stabilization of cross [6e/4p] conjugated systems. We are presently pursuing further application revolving around this methodology

1-Oxa-2,3-cyclohexadiene (I) can be readily generated by treatment of 5-bromo-3,4-dihydro-2H-pyran with potassium tert-butoxide in the presence of 18-crown-6 and can be trapped with dienes or olefins. Thus, the treatment of I with furan gave 50% yield of Diels-Alder adduct II, whereas with 1,1-diphenylethylene I gave 43% of the [2+2]cycloadduct III. The remarkable regio- and stereoselectivities with which [4+2] and [2+2] adducts are formed suggests a concerted, non-radical cycloaddn. mechanism. [on SciFinder (R)]

Stereospecific annulation of hydroxy vinyl ethers in the presence of triflic anhydride and tertiary amines and its synthetic application are described. Each 1-hydroxy-2-oxabicyclo[n.4.0]alkane, 2-oxabicyclo[n.4.0]alk-1(6)-ene and 2-oxabicyclo[n.4.0]alk-1(6+n)-ene is stereoselectively synthesized from the same hydroxy vinyl ether depending on the choice of the reaction conditions (temperature, solvent and tertiaryamine). These compounds lead to polyfunctionalized cyclic compounds and some natural products. We propose that this annulation reaction proceeds through a pure SN2-like mechanism.