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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.

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.

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.

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.

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.

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.

Implantation driven permeation (IDP) behaviour was investigated for deuterium implanted at low energy (100–1800 eV) into pure aluminium to simulate the behaviour of tritium. The experimental results showed that steady state IDP fluxes φP of deuterium depended on the incident deuterium ion (D+) fluxes φi according to the relation φp = α(φ)12, under the following conditions: φi ≈ 7 × 1013 ∼ 1 × 1015 D+ cm−2 s−1, sample temperature approximately 550 ∼ 825 K, and incident D+ ion energy approximately 300 ∼ 1500 eV. This fact suggests that the IDP process through pure aluminium was controlled by recombination of deuterium at the incident surface and by deuterium diffusion at the permeation side. The activation energy for implantation driven permeation of deuterium through pure aluminium was determined to be 59.9 ± 5.0 kJ mol−1 under the above experimental conditions.

The recent results of the Isotope Separation System (ISS) operations at the Tritium Systems Test Assembly (TSTA) with 100 g of tritium indicate that the system generally satisfies design goals, while system stability problems remain to be solved. In this paper, the authors configure the ISS system for the three column mode. which is one of the promising cascade configurations in a fusion fuel cycle, to eliminate such instability and operated it for six days. Fluctuations in flows and liquid levels were improved. Column separation characteristics obtained were satisfactory and agreed with the numerical analysis. The amount of discharged tritium was an acceptable effluent level. This means that the existing ISS system can be used as a three column system and possibly be applied to numerous fuel concepts. Presently, a new laser Raman spectroscopic gas analyzer has been installed at the ISS. This on-line system enables studies of the ISS dynamic behavior for further stability and performance data.

A brief survey on recent advances in the field of tritium technology concerning the most important systems of the fuel cycle of a fusion reactor, i.e. the plasma exhaust pumping system, the exhaust gas clean up system, the isotope separation system, the tritium storage facility and the tritium extraction from a blanket is provided. Experimental results, single component developments, and technical tests including those with relevant amounts of tritium that constitute the basis of proposed integral process concepts are described.

The Tritium Process Laboratory (TPL) at the Japan Atomic Energy Research Institute (JAERI) has developed a Fuel Cleanup System (FCU) which accepts simulated fusion reactor exhaust and produces pure hydrogen isotopes and tritium-free waste. Under the collaboration program of USDOE and JAERI, an integrated process, the “JAERI Fuel Cleanup System” (JFCU) was designed and fabricated for testing at the Tritium Systems Test Assembly (TSTA) as a major subsystem of the simulated fusion fuel cycle. The JFCU has the capability to continuously process a mixture of hydrogen isotopes and impurities of 15 mol/h. The major components are: a palladium diffuser for hydrogen isotopes purification, a catalytic reactor for oxidation of tritium in impurities, cold traps for separation of tritiated water to produce exhaust containing a very low level of tritium, a ceramic electrolysis cell for decomposition of tritiated water, and zirconium-cobalt beds for hydrogen isotopes storage. In early 1990, the JFCU was installed in the TSTA and preliminary testing without tritium was initiated. Components such as the palladium diffuser, cold traps, catalytic reactor, scroll pump and electrolysis cell were tested independently as well as in the integrated process tests.

Application of laser Raman spectroscopy for fusion fuel gas processing was studied by measuring isotopic methanes exchanged with hydrogen isotopes, which are considered to be a major impurities in the processing. For experimental gases, isotopically equilibrated deuterium and methane were prepared in the presence of solid catalyst. Large Raman scattering peaks of v 1, bands were observed at 2,917 cm−1 for CH4 and at 2,100-2,200 cm−1 for deuterated derivatives of methane C(H,D)4. Under a spectral resolution of 5 cm−1, the v 1 bands of CH3D and CH2D2 were observed as an overlapped peak, the relative absolute Raman intensity ratio of each isotopic methane was obtained as CH4: CH3D+CH2D2: CHD3: CD4=230: 74: 144: 100. On the other hand, the Raman intensity ratio obtained from pure deuterated standard methane was CH4: CH3D: CH2D2: CHD3: CD4=230: 53: 33: 115: 105. It was confirmed that isotopically equilibrated hydrogen isotopes and methane mixed gas would be applicable for an alternative standard gas for fusion...

Under a collaborative agreement between US and Japan, two tritium processing components, a palladium diffuser and a ceramic electrolysis cell have been tested with tritium for application to a Fuel Cleanup System (FCU) for plasma exhaust processing at the Los Alamos National Laboratory. The fundamental characteristics, compatibility with tritium, impurities effects with tritium, and long-term behavior of the components, were studied over a three year period. Based on these studies, an integrated process loop, JAERI Fuel Cleanup System'' equipped with above components was installed at the TSTA for full scale demonstration of the plasma exhaust reprocessing.

An overview is given of the design, construction and initiation of the operation of the facility, Tritium Process Laboratory, JAERI, to study and develop tritium processes for fusion fuel cycle and safe handling technology.

We apply an orbital phase theory to the torquoselectivity of the electrocyclic reactions of 3-substituted (X) cyclobutenes. The torquoselectivity is shown to be controlled by the orbital-phase relation of the reacting pi(CC) and sigma(CC) bonds with the sigma(CX) bond geminal to the sigma(CC) bond to be cleaved. The inward rotation of electron-donating sigma(CX) bonds and outward rotation of electron-withdrawing sigma(CX) bonds have been deduced from the orbital-phase theory. Enhancement of the inward rotation by the electron-donating capability of the sigma(CX) bonds is confirmed by the correlation between the torquoselectivity and sigma(CX) orbital energy. The orbital overlaps between the geminal sigma(CX) (sigma(CH)) and sigma(CC) bonds are found to be important as well. Unsaturated substituents with low-lying unoccupied pi orbitals also promote the inward rotation.

The Tritium Systems Test Assembly (TSTA) project at Los Alamos National Laboratory is charged with developing and demonstrating the fusion fuel processing requirement for the magnetic fusion energy program. The key fusion fuel streams are the plasma exhaust and the blanket stream. At present, the technology under development at TSTA includes only the plasma exhaust. The blanket is a logical upgrade to TSTA and the upgrade is the subject of an ongoing study. The program, called the Breeding Blanket Interface (BBI), is being investigated with the intention of installing such a processing system at TSTA in the 1992-1993 time frame. The BBI program was initiated in July, 1987. The conditions of the tritium product streams of various blankets were determined. Pre-conceptual designs of the BBI systems were developed for two blanket concepts: aqueous lithium salt solution blanket and solid breeder blanket. Preliminary estimates of costs have been performed and the schedule of the TSTA/BBI program has been developed. The schedule and planning of the TSTA/BBI program are discussed. The goal of the program is to establish the engineering data basis of the fuel cycle for an International Thermonuclear Engineering Reactor. >

The Tritium Systems Test Assembly (TSTA) at Los Alamos, New Mexico, is a full-scale facility dedicated to testing tritium processing for fusion reactors. Adding a breeder blanket interface (BBI) to the TSTA is being studied. The BBI is to test the processing required for the tritium output streams for the various fusion-reactor breeder blankets. In the current phase of the study, the characteristics of the output from the various blanket types are being evaluated. Defining the output stream with respect to H/T ratio, impurity content, and radionuclide content is emphasized. Assessments of the solid breeder blanket (ceramic, Li/sub 2/O) and the aqueous salt solution blanket are reported. For the aqueous lithium salt solution blanket, the chemical systems are very complex, involving a number of phenomena, including radiolysis, corrosion, and electrolysis. A system of about 0.01 ITER scale may be added to the TSTA. For the solid breeder blanket, no critical issues are identified. A system of about half-ITER scale, possibly even full scale, may be added to the TSTA. >

The Tritium Systems Test Assembly (TSTA) at Los Alamos National Laboratory has conducted its longest continuous integrated loop operation to data. This provided an opportunity to test some hitherto unproven capabilities of the TSTA fuel cleanup system (FCU). The purpose of the FCU is to remove impurities from a stream of hydrogen isotopes (Q/sub 2/) representative of torus exhaust gas. During this run, impurities loadings ranging from 60 to 179 sccm of 90% N/sub 2/ and 10% CH/sub 4/ were fed to the FCU. Each of the two FCU main flow molecular sieve beds (MSBs) were filled to breakthrough three times. The MSBs were regenerated during loop operations. The experiment yielded two principle findings. The first is that using the cryogenic molecular sieve is very robust method for removing impurities from fusion fuels. While loop flow rates, pressures, and impurities concentrations varied, the MSBs continued unaffected, completely removing impurities. The second is that the first step in the MSB regeneration process proved to be very effective. >

This paper discusses the possibility that tritium might exchange with water trapped in aluminum anodize cryopanels in JET which prompted a test program at the Tritium systems Test Assembly, TSTA. Los Alamos, New Mexico. JET furnished two test pieces of cryopanel which were exposed to tritium at approximately liquid nitrogen temperature and 25 torr pressure for nearly two weeks. One specimen was removed and the retained tritium was measured. The second specimen was subjected to several increasing temperature vacuum bakeouts and the effectiveness of the bakeouts were inferred from the pressure history of the chamber. When the retained tritium in the second specimen was measured, it was found that nearly 96% of the tritium, as measured in the first specimen, had been removed during the vacuum bakeouts. If the tritium retained in the cryopanel without bakeout were scaled to JET conditions according to a linear pressure-time relationship, the tritium expected to become trapped in the JET cryopanels would be approximately 0.6 gram.

In 1988, a prototypical vacuum system was added to the Tritium Systems Test Assembly (TSTA) at Los Alamos National Laboratory. Since then various pumping scenarios, which might be expected in a fus...

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

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

The Tritium Process Laboratory (TPL) was constructed at the Japan Atomic Energy Research Institute (JAERI) in June, 1985. The objectives of this laboratory are the research and development of the fusion reactor fuel processing system and safe handling technology of large amounts of tritium. Total tritium inventory in the facility is 10 g and each experiment will be conducted with up to 1 g. Safety systems have been in operation since 1985 and have been tested without tritium. Tritium removal systems, gloveboxes, vacuum pumping system and tritium storage systems etc. have been proven to work as designed so that tritium can be handled safely in this facility. The various items of experimental apparatus were designed, fabricated, installed and checked early in 1988. First tritium was shipped from Oak Ridge National Laboratory in February, and then the “hot” operation was initiated in March, 1988.

A ZrCo intermetallic compound is proposed as the material for recovery, storage and supply of gaseous tritium. It is a substitute for the uranium that has been extensively used for this purpose in spite of its restricted handling as a nuclear fuel material. Pressure-composition isotherms of a ZrCoH2 system were investigated and this material proved to be applicable and advantageous. Some ZrCo beds were designed, fabricated and tested for actual use. A bed for the handling of large amounts of hydrogen isotopes was developed. The test establishes ZrCo beds as practical components for tritium service.

Cryogenic distillation experiments were performed at TSTA with H-D-T system by using a single column and a two-column cascade. In the single column experiment, fundamental engineering data such as the liquid holdup and the HETP were measured under a variety of operational conditions. The liquid holdup in the packed section was about 10--15% of its superficial volume. The HETP values were from 4 to 6 cm, and increased slightly with the vapor velocity. The reflux ratio had no effect on the HETP under the condition that the vapor velocity was almost constant. For the two-column experiment, dynamic behavior of the cascade was observed.

This paper will review the current state-of-art of organoaluminum- or organoboron-mediated asymmetric reactions in the natural product synthesis. The newly developed methods heavily depend on the characteristic features of main group organometallic compounds. Asymmetric Diels-Alder reaction, pioneered by Walborsky (ref. l), has been established as one of the most important tools in modern synthesis of natural products. In the study of the influence of concave-convex topological features on asymmetric Diels-Alder reactions, a number of fascinating chiral auxiliary groups were reported (ref. 2). However, readily available dimen- thy1 fumarate appears to deserve careful reinvestigations since its primitive topological feature seems to be underestimated. Thus, the Lewis acid coordinated fumarate is considered to exist in the s-trans form predominantly and the two menthyl groups should cooperatively cover the re face of the molecule. A series of dienes was then subjected to Diels-Alder reaction with or- ganoaluminum reagent at low temperature and all the attempted reaction proceeded with excel- lent stereoselection (ref. 3).