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Organic single crystals with elastic bending flexibility are rare because they are generally brittle. We report here fluorescent organic single crystals based on thiophene-tetrafluorobenzene-thiophene derivatives, mainly 1,4-bis(thien-2-yl)-2,3,5,6-tetrafluorobenzene. Three derivatives were synthesized by Pd-catalyzed cross-coupling reactions (Stille or direct arylation pathways). The crystallization of the derivatives gave large (mm- or cm-scale) crystals. Two crystals of 1,4-bis(thien-2-yl)-2,3,5,6-tetrafluorobenzene, 1, and 1,4-bis(4-methylthien-2-yl)-2,3,5,6-tetrafluorobenzene, 3, bent under applied stress and quickly recovered its original shape upon relaxation. The other crystal of 1,4-bis(5-methylthien-2-yl)-2,3,5,6-tetrafluorobenzene, 2, showed brittle breakage under applied stress (normal behavior). Fibril lamella crystal structure based on criss-cross packed slip-stacked molecular wires and its structural integrity are important factors for the design and production of next generation crystal materials with elastic bending flexibility. Furthermore, mechanical bending–relaxation resulted in reversible change of the morphology and fluorescence (mechanofluorochromism). Such bendable crystals would lead to the next generation solid-state fluorescent and/or semiconducting materials.

The most stable sorption site of dimethyl ether on silicalite-1 is the sinusoidal channel. The configuration of guest molecules (linear or bent) plays an important role in determining where the stable sorption site is situated., The adsorption structures of dimethyl ether (DME) on silicalite-1 zeolite (MFI-type) are determined using single-crystal X-ray diffraction. The structure of low-loaded DME-silicalite-1 indicates that all DME molecules are located in the sinusoidal channel, which is the most stable sorption site based on the van der Waals interaction between DME and the framework. The configuration of guest molecules (linear or bent) plays an important role in determining where the stable sorption site is in the pore system of MFI-type zeolites. Bent molecules favor the sinusoidal channel, while linear molecules favor the straight channel. The contribution of DME–DME interactions is considerable in the high-loaded DME-silicalite-1 structure.

The process of CO2 adsorption on silicalite-1 zeolite (MFI-type) is revealed using a single-crystal X-ray method. The structure of CO2-silicalite-1 with a small amount of CO2 in the pore is determined, wherein most of CO2 molecules are located in the straight channel. It indicates the straight channel is the most stable sorption site based on the van der Waals interactions between the CO2 and the framework, and the CO2 molecules initially adsorb in the straight channel in the adsorption process. This is the first report to describe the structure of MFI-type zeolites with the adsorbate molecules occupying only the straight channel.

Structural analysis of CO2-silicalite-1 crystals using the single-crystal X-ray diffraction method reveals that the crystal system is twinned monoclinic. The structure of silicalite-1 (MFI-type zeolites) loaded with CO2 has previously been solved in orthorhombic system [1], but the R value is still large. Since CO2 molecules are too small to maintain the orthorhombic structure, it is considered that the CO2-silicalite-1 crystals should be in the relaxed monoclinic twin phase. The diffraction data in the previous report is recalculated in P21 /n as the monoclinic twinning.

The actual adsorption structures of non-aromatic hydrocarbons on the MFI-type zeolites have not yet been determined. This is due to the presence of twinning, which makes crystallographic analysis difficult. We recently overcame this problem, and now report the various adsorption structures of n-butane, n-pentane, n-hexane, 1-butene, cis and trans-2-butene, 2-butyne and isopentane on silicalite-1 (MFI-type zeolite) as determined via single-crystal X-ray diffraction. The structures were elucidated for both low and high loadings of each guest molecule in order to clarify the adsorption process. The low-loaded structures provide valuable insight into guest-framework interactions and initial adsorption behavior. The n-alkanes are initially adsorbed in the sinusoidal channel, while 2-butyne is adsorbed in the straight channel. In the case of the normal hydrocarbons, the molecular configuration (bent or linear) of the compound determines which channel is the preferred adsorption site. Bent molecules prefer the sinusoidal channel and linear molecules prefer the straight channel. In contrast, isopentane is initially adsorbed at the intersection, since the channels are too narrow to maintain the preferred distance between the framework and the bulky isopentane molecule. In the high-loaded structures, the guest molecules occupy additional sites, such that the normal hydrocarbons are located in both channels and isopentane is found at the intersection and the sinusoidal channel.

The location of physisorbed CO2 molecules on silicalite-1 zeolite (MFI-type) is determined using a single-crystal X-ray method. There are four sorption sites for CO2 molecules in the three-dimensional channel system of the silicalite-1. Two of them are in the straight channel in disorder (STR1 and STR2), while the other sites are in the sinusoidal channel (SIN) and at the intersection (INT). Their occupancy factors indicate that a large portion of the CO2 molecules are located in the straight channel. It is also revealed that the straight channel is the most favorable for CO2 molecules as sorption sites.

The adsorption process of phenol on silicalite-1 was studied by single-crystal X-ray diffraction. The loading of phenol on silicalite-1 was performed for 24, 48, 72, and 168 h. Phenol molecules first diffused through the intersection forming hydrogen bonds with the oxygen atoms of the framework and then subsequently turned into the sinusoidal channel. As adsorption progressed, phenol molecules were located at the intersection and in the sinusoidal channel, and these two kinds of phenols interacted with each other. High-loaded phenol–silicalite-1 (8.0 molecules/unit cell) was obtained after 168 h of adsorption. It is clear that hydrogen bonds were present in the framework, based on the results of the single-crystal XRD measurements and an IR study.

An orthorhombic benzene-silicalite-1 single crystal was obtained from a monoclinic twin crystal, and the structure was determined by a single-crystal method for the first time., A simple method for preparing orthorhombic single crystals of benzene-silicalite-1 was developed. A silicalite-1 crystal was pressed with a weight of 2 g along the +c and −c crystallographic axes while the temperature was increased to 473 K. The temperature was then slowly reduced to 313 K, and these heating and cooling steps were repeated three times. After the orthorhombic single crystals adsorbed benzene, the crystal structure of the resulting benzene-silicalite-1 was determined. There were two kinds of benzene molecules in the asymmetric unit. One was located at the intersection of the straight channels and the sinusoidal channels with the benzene ring parallel to the ac plane. The other benzene was located in the middle of the straight channel.

Synthesis of ω-chlorinated alkyl phenyl ethers by tandem reaction of arynes with cyclic ethers and active methines was achieved. Reaction of benzenediazonium 2-carboxylate with tetrahydropyran or t...

A simple method for preparing monoclinic single crystals of ZSM-5 is developed. The ZSM-5 crystals are pressed with a weight of 50 g at an angle of 45° relative to the b and c crystallographic axes of twin ZSM-5 crystals while the temperature is simultaneously increased to 573 K. The temperature is then slowly reduced to 313 K, and these steps are repeated three times. The monoclinic structure of the single crystals of ZSM-5 produced using this method is then determined.

The reaction of 4,4-di-tert-butyl-1,2-dithietan-3-one with triphenylphosphine afforded 1,1-di-tert-butylthiiran-2-one (86%). The reaction of 4,4-di-tert-butyl-1,2-dithietan-3-one with phenylmagnesi...

The crystal structures of the 1:1 complexes methylguanidinium benzylhydrogenmalonate, (C2N3H8)+(C10H9O4)−, MGD.BMAL, and methylguanidinium ethylhydrogenmalonate, (C2N3H8)+(C5H7O4)−, MGD.EMAL, and of the 2:1 complex methylguanidinium sulfate, (C2N3H8)2SO4, have been determined from three-dimensional X-ray data. For MGD.BMAL, the complex crystallizes in the triclinic space group P with two formula units in a cell of dimensions a = 6.277(5), b = 8.470(3), c = 13.191(6)A, α= 91.01(1), β= 99.64(9), γ= 90.83(5)°. The structure has been refined to a final value of R = 0.061 based on 1511 intensities. The MGD.EMAL complex is also triclinic, space group P with two molecules in a cell of dimensions a = 9.254(7), b = 9.625(6), c = 6.778(2) A, α= 109.6(1), β= 100.8(1), γ= 62.7(1)A. The crystals of this compound are of low quality, and the final value is R = 0.109 based on 706 intensities. (MGD)2SO4 is orthorhombic, space group P212121, with four molecules in a cell of dimensions a = 7.100(4), b = 12.151(3), c = 13.108(2) A. Refinement has converged to R = 0.054 based on 907 data. All three crystals exhibit extensive interionic hydrogen bonding. The hydrogen bonding in MGD.BMAL includes a Type B interaction and a Type 1 interaction, the latter being a pairwise interaction from both amino nitrogen atoms on the cation to two carboxylate oxygen atoms from the two different carboxylate groups in an anion. In MGD.EMAL, the anion participates in both a Type A and a Type B pairwise interaction with two neighboring cations. The possible implications of the hydrogen bonding patterns in these two compounds for the role of arginyl side chains in protection of γ-carboxyglutamate residues from decarboxylation are discussed.

The crystal structure of pollucite (ANA) (Cs,Na)AlSi2O6is characterized by single-crystal X-ray diffractometry. The space groupC2/c,monoclinic, is found to be the most probable space group for this mineral based on the systematic absences of reflections. Cesium ions or water molecules are disordered at the center of a channel and are slightly apart from the special position. This is the origin of symmetry breaking and the space group becomes lower fromIa-3d(analcime) toC2/c. Sodium ions or vacancies are located at the contact point of the channel. No ordering of aluminum is observed in the pollucite structure.

The reaction of benzenediazonium carboxylate with chloroform in refluxing tetrahydrofuran afforded 5,5,5-trichloropentyl phenyl ether in 61% yield along with benzoic acid (7%). When dichloroacetonitrile was used as a reactant, 5,5-dichloro-5-cyanopentyl phenyl ether was obtained in 65% yield. Reactive benzyne derived from diazonium carboxylate initially reacted with THF to give a dipole intermediate, which further reacted with chloroform or dichloroacetonitrile to give ring opened products.

Sulfurization of β-dithiolactone (4) gave corresponding 1,2-dithiolane-3-thione (2a) via an ionic intermediate. Oxidation of β-dithiolactone 4 by m-CPBA afforded corresponding S-oxide (11), while dioxide (12) was obtained when 3 equiv of m-CPBA was used. Dithiolane-3-thione 2a reacted with ethylenebis(triphenylphosphine)platinum or tetrakis(triphenylphosphine)palladium to afford the corresponding dithiolato-platinum (20) and dithiolato-palladium (21) complexes in good yields.

Single crystals of TPA-ZSM-5 were synthesized using KOH as a mineralizer instead of NaOH. The size of the TPA-ZSM-5 crystals after 120 h was approximately 100 μm. When KOH was used, the quantity of TPA-ZSM-5 crystals formed was increased, and Al distribution in the crystal was uniform. The form and quality of these crystals were suitable for single crystal X-ray diffraction. Nucleation of the analcime by-product, which is formed in the presence of NaOH, is inhibited when KOH is used, because the potassium ion does not act as a template for the analcime structure. Instead, zeolite W was observed as a by-product. However, compared to analcime, the amount of zeolite W was lower, and it was easier to separate from TPA-ZSM-5. Thus, potassium ions play an important role in the production of large quantities of high-quality ZSM-5 with a uniform Al distribution.

2-Arylquinolines 1 were obtained in good yields by reacting iodine or NIS with 2-aminochalcones 2, which were easily synthesized by the Claisen–Schmidt reaction from 2-nitrobenzaldehyde and acetoph...

Thermolysis of 3,3-di-tert-butylthiirane-2-thione S-oxide 4 gave di-tert-butyl ketone 5 and carbon disulfide (CS2). Treatment of α-dithiolactone S-oxide 4 with excess m-CPBA or triphenylphosphine gave di-tert-butylthioketene S-oxide 3 almost quantitatively. Treatment of 4 with (η2-ethylene)bis(triphenylphosphine)platinum(0) 13 or tetrakis(triphenylphosphine) palladium 17 resulted in the formation of thiolato sulfinato–platinum complex 15 or palladium complex 18, respectively. The structure of complex 15 was determined by X-ray crystallographic analysis.

Cycloadditions of 2-diphenylphosphinoyl-2-methyl-3,4-dihydro-2H-pyrrole N-oxide (DPhPMPO), 3,4-dihydro-2H-pyrrole N-oxide having a diphenylphosphinoyl group at the C2 position with thioketones afforded the corresponding 1,4,2-oxathiazolidines. Dissociation constants of these 5-membered ring products were determined. The cycloadducts were stabilized by the diphenylphosphinoyl group. The reaction of DPhPMPO with di-tert-butyl selenoketone gave the corresponding selenoamide under microwave irradiation. The formation of the selenoamide indicated that the cycloaddition of DPhPMPO with the selenoketone analogue also proceeded through the formation of the corresponding 5-membered ring product.

The synthesis of selenoketone–platinum complexes 3a–3c was achieved by reacting selenoketones 4 with (η2-ethylene)bis(triphenylphosphine)platinum(0) (1). 1,1,3,3-Tetramethylindan-2-selone–platinum ...

Sterically congested cis- and trans-Δ 3 -1,3,4-selenadiazolines were isolated by one-pot reactions of ketone hydrazones with diselenium dibromide, which suggested the in situ formation of selone and diazoalkane intermediates. The thermolysis of these compounds gave symmetrical olefins, whereas oxidation afforded the corresponding azines. The reaction of acetophenone hydrazones with diselenium dibromide afforded 2,5-diarylselenophenes in moderate yields. The reaction proceeded through selone intermediates.

The structure of a high-loading complex of ZSM-5 with 6.4 toluene molecules per unit cell has been determined by single-crystal X-ray diffraction. At least three kinds of toluene molecules were identified in the unit cell. Two disordered toluene molecules were located at the intersection of the straight and sinusoidal channels, the third in the sinusoidal channel. One (TOL1) of the two toluene orientations at the intersection was similar to that of p-dichlorobenzene at the intersection in high-loaded H-ZSM-5/p-xylene (hereafter 8PARA) and high-loaded H-ZSM-5/p-dichlorobenzene (hereafter 8PDCB) complexes, respectively. The other toluene orientation (TOL2) at the intersection was similar to those of p-xylene or p-dichlorobenzene at the intersection in the low-loaded p-dichlorobenzene complex (hereafter 2.6PDCB). A third toluene orientation (TOL3) existed in the sinusoidal channel; its orientation was similar to those of p-xylene and p-dichlorobenzene in the sinusoidal channels in 8PARA and 8PDCB complexes, respectively. If the occupancy of TOL2 at the intersection increases with temperature, TOL2 will connect with TOL3 in the sinusoidal channel and form the intermediate diphenylmethane

The entrance and diffusion pathway of CO2and dimethyl ether (DME) in MFI-type zeolite channels were investigated by a selective sealing method using large silicalite-1 crystals. The MFI-type zeolite has two kinds of orthogonal channels: straight channels and sinusoidal channels. The mouths of the straight channels are on (010) crystal faces, while those of the sinusoidal channels are on (100) faces. The channel mouths are directly sealed by silicone resin on the (100) and (010) faces so as to restrict the entrance and diffusion pathways to straight and sinusoidal channel pathways, respectively. The locations and loadings of the guest CO2and DME molecules are determined by single-crystal X-ray diffraction structural analysis. The loadings show the difference of the adsorption rates between the pathways. The straight channel pathway is 4.2 times faster than the sinusoidal channel pathway for the CO2, and the sinusoidal channel pathway is 5.1 times faster than the straight channel pathway for the DME. It reveals their dominant pathways and the anisotropy of adsorption. The dominant pathway correlates to the stability of the channel as adsorption sites.

The structure of natural ferrierite (from Kamloops Lake) is determined. The space group is not Immm but I222 (no. 23) and its R-factor is 8.6%. All 18 H2O molecules, Na+, and Mg2+ ions are successfully assigned [Mg1.6(Ca0.1Ba0.1Na1.6K0.4)Al5.8Si30.2O72·18H2O]. The angle of T(41)–O(5)–T(42) is 168° because the O5 site is not located on an inversion center in I222 space group. We also determined Bronsted acid sites. The Al atom distribution in the framework is also discussed and the T(1), T(2), and T(42) [or T(41)]-sites are the most probable sites.

Selenobenzophenone reacts as a diene with dimethyl acetylenedicarboxylate (DMAD) to lead to dimethyl 1H-1-diphenylmethyl-1-phenyl-2-benzoselenopyran-3,4-dicarboxylate (5c) in moderate yield; the initial [4 + 2] cycloaddition is followed by the addition of another 1 mol equiv of selenobenzophenone. The reaction might proceed through carbene insertion of the primary cycloadduct. On the other hand, 4,4'-dimethoxyselenobenzophenone combines as a diene with DMAD furnishing dimethyl 1H-1-p-methoxyphenyl-6-methoxy-2-benzoselenopyran-3,4-dicarboxylate (4a). The reaction of benzoselenopyran derivative (4) with diaryldiazomethanes afforded another type of carbene insertion product.

The reaction of thiobenzophenones (1) with phenyl[2-(trimethylsilyl)phenyl]iodonium trifluoromethanesulfonate (4) in the presence of tetrabutylammonium fluoride afforded the corresponding [4+2] cycloadducts, which are the first examples of thiobenzophenone-benzyne adducts. The reaction of thiopivalophenone (6) with benzyne prepared from 4 and tetrabutylammonium fluoride at room temperature gave [2+2] cycloadducts (7). When the reaction was carried out in refluxing dichloromethane, a mixture of 7 and [4+2] cycloadducts (13) was obtained.

A crystal of TPA-ZSM-5 with Si/Al=23 was synthesized by an extended Charnell's method with a size of over 200 μm. The space group of the crystal was not Pnma but Pn21a (no. 33), and its R-factor was 7.2%. TPA+ was also successfully found. It is very difficult to explain the reason why TPA-ZSM-5 with Si/Al=23 (i.e. (TPA+)4[Al4Si92O192]) is very stable with the Pnma space group because Pnma has eight general equivalent positions. However, it is easy to explain why the crystal is stable with the Pn21a space group because there are four general equivalent positions. We suggest three possible positions of Al (T(1), T(15) and T(18)) in 24 independent T-sites, and find that the T(1)-site should be the most probable.

Treatment of α-dithiolactone 6 with ethoxycarbonylformonitrile oxide 7 resulted in the formation of 1,2-dithietan-3-one 4. Compound 4a was oxidized with m-CPBA to give 4,4-di-tert-butyl-1,2-dithietan-3-one 1-oxide 5a. The reaction of 4a with triphenylphosphine afforded the corresponding α-thiolactone 10.

Crystals of analcime were synthesized; the size was about 200 μm. The diffraction data were collected with both cubic system and trigonal system from the same crystal. The crystal parameters were completely cubic and the space group was Ia3d, but the R-factor only dropped to about 10%. The R-factor was lowered to 0.048 with the trigonal system. This result shows that every pseudo-cubic or average cubic analcime is really trigonal (R3¯). The unit cell size is a half of the cubic cell size, i.e. Na8[Al8Si16O48] · 8H2O, a = 11.909(5) A, α = 109.51(3) °.

The Fukushima nuclear accident has highlighted the importance of finding a better final storage method for radioactive cesium species. Cs is highly soluble in water, and can easily exchange with other alkali ions in zeolites or clays to form stable complexes. However, Cs(+) is released from Cs(+) complexes into water when surrounded by an excess of water. Pollucite may be the best final storage option for Cs(+), but its typical synthesis requires heating to about 1200 °C in air. Here, we show that the hydrothermal synthesis of pollucite can be completed at 300 °C in three hours from any zeolite or clay. Furthermore, our procedure does not require ion exchange before synthesis. Radioactive Cs is usually found in complexes with clays. At that time, this method only requires calcium hydroxide, water, and three hours of hydrothermal synthesis, so the process is both inexpensive and practical for large-scale application. Pollucite is an analog of analcime zeolite, and contains a channel system 2.8 A in diameter, which is formed by 6-oxygen rings. As the diameter of Cs(+) is 3.34 A and each Cs(+) exists independently within a separate portion of the channel, Cs(+) cannot exit the pollucite framework without breaking it.

The reaction of selenobenzophenones with tetracyanoethylene (TCNE) exclusively affords an unusual type of adduct with the structure of 2,3-dihydroselenophene, sharply different from the reaction between thiobenzophenone and TCNE

Oxidation of 1,2-dithietes with 1 equiv of MCPBA gives the corresponding 1,2-dithiete S-oxides, while oxidation with more than 2 equiv of MCPBA affords three geometrical isomers of ethane-1,2-dithione S.S′-dioxides (α-disulfines) with opening of the four-membered ring.

Treatment of adamantane-2-thione (1a) with propiolic acid (2a) afforded a novel type of cycloadduct, spiro[adamantane-2,2′-[1,3]oxathiin]-6-one (3a), in quantitative yield. The reaction proceeds through a concerted process, as was confirmed by kinetic analysis. Treatment of 1a with butynoic acid or phenylpropiolic acid gave the corresponding adducts regioselectively. Interestingly, only one isomer was obtained by treatment of thiofenchone with propiolic acid, suggesting that the reaction proceeded stereospecifically. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

The reaction of diaminosulfoxonium ylides with aldehydes gave the corresponding cyclopropyldiaminosulfoxonium salts in good yields when 1,8-diazabicyclo[5.4.0.]undec-7-ene (DBU) was used as a base. These ylides reacted with aldehydes to give the corresponding betaines, which resulted in the formation of vinylsulfoxonium salts. The additional ylides reacted with these salts to afford cyclopropylsulfoxonium salts. The reaction of these salts with potassium hydroxide is also described.

4,4′-Dimethoxy-1a and 4,4′-dimethyl-selenobenzophenone 1b could be isolated in moderate yields by the reaction of the corresponding ylides 3 with elemental selenium in benzene at 80 °C. Their spectral data are described. Attempted isolation of unsubstituted selenobenzophenone afforded only its dimer 5. Compound 1a crystallizes in space group P21/n with unit-cell parameters a= 7.191(3), b= 7.505(4), c= 24.856(4)A, β= 90.32(1)°, Z= 4, R= 0.055. The oxidation and thiation of 4,4′-dimethoxyselenobenzophenone 1a afforded the corresponding benzophenone and thiobenzophenone in good yields. The reaction of compound 1 with cyclopentadiene afforded the corresponding cycloadducts 7(3,3-diaryl-2-selenabicyclo[2.2.1] hept-5-enes), whereas bicyclic diselenides 8(4,4-diaryl-2, 3-diselenabicyclo[3.3.0]oct-7-enes) were obtained by using an excess of selenium and a higher temperature. Oxidation of compound 8c gave the corresponding diol 12, aldehyde 13, and diphenylfulvene 11. The reaction of compound 1a with benzenediazonium carboxylate afforded 2,2- bis-(4-methoxyphenyl)-4H-3,1 -benzooxaselenin -4-one 17.

合成油 (ポリαオレフィン (PAO), ジアルキルアジペイト (DA), トリメチロールプロパンエステル (TMP))に対する硫黄系極圧剤, リン酸エステルおよびジチオリン酸亜鉛 (ZDP) の焼付き防止効果を検討し, これら合成油中における各添加剤の鉄粉への吸着性, および鉄粉上の熱分解性または加水分解性と比較した。各添加剤の焼付き防止効果の大小は, 合成油について硫黄系極圧剤ではDA>PAO, TMPまたはPAO≧DA>TMP, リン酸エステルではPAO>DA, TMP, ZDPではPAO>TMP>DAであった。これらの焼付き防止効果の序列は, 硫黄系極圧剤では主に熱分解性に左右され, リン酸エステルでは主に吸着性に左右され, ZDPでは吸着性と熱分解性に左右された。

Several racemic indolinones (V) are obtained by reaction of amino acid esters (IV) with in situ generated benzyne.

Reaction of thiocamphor (I) with disulfur dichloride affords six- and seven-membered tricyclic polysulfanes (II) and (III), respectively, which are oxidized by MCPBA to give bicyclic (E,E)-α-disulfine (IV) stereoselectively.

The structure of 2-hydroxycyclohexanespiro(2′-cyano-2′-methoxycarbonyl)cyclopropane, prepared by the reaction of 1,2-epoxy-1-(nitromethyl)cyclohexane with methyl sodiocyanoacetate, has been determined from X-ray diffraction data. There are two independent molecules in an asymmetric unit. The geometry of cyclopropane is discussed.

A sterically hindered ketone, 2,2,5,5-tetramethyl-4,4-diphenyl-3-thiolanone (1), was synthesized in two steps starting from 2,2,4,4-tetramethyl-1,5-diphenyl-3-thiapentane-1,5-dione. The carbonyl group of 1 is unreactive toward a series of nucleophiles which are bulkier than hydride or its equivalents. The observed unreactivity is ascribed to the steric hindrance enhanced by the two methyl groups on C-5 (“buttressing” effect). The result of an X-ray single crystal structure analysis of 1 is also described.

Irradiation of 2-methyl-1-phenylpropane-1,3-diones (1a-c) in 2-propanol gave trioxatricyclononanes (2a-c), (3a,b) and (4a). Irradiation of 1,3-diaryl-2-methylpropane-1,3-diones (1d and 1e) gave trioxatricyclononanes (2d and 2e), dl-pinacols (5d and 5e), and the dioxabicyclooctane dihemiacetal (6). The dihemiacetal (6) underwent dehydration on heating to give the trioxatricyclononane (3d). Treatment of (2d,e), (5d,e), and (6) with hydrochloric acid gave dioxabicyclooctadienes (7a and 7b), while that of (2a-c), (3a,b) and (4a) with hydrochloric acid gave 3-methylenecyclopentenes (8a-c) and the epoxycycloheptenone (9)

The reaction of diaminosulfoxonium ylides with aldehydes gave the corresponding cyclopropyldiaminosulfoxonium salts in good yields when 1,8-diazabicyclo[5.4.0.]undec-7-ene (DBU) was used as a base. These ylides reacted with aldehydes to give the corresponding betaines, which resulted in the formation of vinylsulfoxonium salts. The additional ylides reacted with these salts to afford cyclopropylsulfoxonium salts. The reaction of these salts with potassium hydroxide is also described.

The reaction of selenobenzophenones with tetracyanoethylene (TCNE) exclusively affords an unusual type of adduct with the structure of 2,3-dihydroselenophene, sharply different from the reaction between thiobenzophenone and TCNE

The reaction of thiobenzophenones (1) with phenyl[2-(trimethylsilyl)phenyl]iodonium trifluoromethanesulfonate (4) in the presence of tetrabutylammonium fluoride afforded the corresponding [4+2] cycloadducts, which are the first examples of thiobenzophenone-benzyne adducts. The reaction of thiopivalophenone (6) with benzyne prepared from 4 and tetrabutylammonium fluoride at room temperature gave [2+2] cycloadducts (7). When the reaction was carried out in refluxing dichloromethane, a mixture of 7 and [4+2] cycloadducts (13) was obtained.

Selenobenzophenone reacts as a diene with dimethyl acetylenedicarboxylate (DMAD) to lead to dimethyl 1H-1-diphenylmethyl-1-phenyl-2-benzoselenopyran-3,4-dicarboxylate (5c) in moderate yield; the initial [4 + 2] cycloaddition is followed by the addition of another 1 mol equiv of selenobenzophenone. The reaction might proceed through carbene insertion of the primary cycloadduct. On the other hand, 4,4‘-dimethoxyselenobenzophenone combines as a diene with DMAD furnishing dimethyl 1H-1-p-methoxyphenyl-6-methoxy-2-benzoselenopyran-3,4-dicarboxylate (4a). The reaction of benzoselenopyran derivative (4) with diaryldiazomethanes afforded another type of carbene insertion product.