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Newly designed chiral cobalt(III) complexes, e.g. (I), are applied to the enantioselective borohydride reduction of aliphatic ketones using 1,1,1-trichloroethane to generate the corresponding 1-chlorovinyl cobalt(III) derivatives as reactive intermediate.

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.

The hitherto unknown stereochemistry concerning the formation of 2,3-disubstituted cycloheptanones by the Michael addition reaction was studied. The Michael addition of thiophenol to 3-substituted 2-methylene-cycloheptanones in the presence of triethylamine in THF at ambient temperature produced 3-substituted 2-[(phenylthio)methyl]cycloheptanones with high cis selectivity (>96/4), which was unequivocally established by 1 H NMR and X-rays analyses

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

Highly functionalized, unsymmetrical disulfides (presumed metabolites of a bioactive sulfide) were synthesized by a base-induced, crossed reaction of two different symmetrical disulfides. The reaction was also applied to the preparation of a vitamin B1 derivative, Prosultiamine.

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.

A series of 8'-substituted N-(endo-8-azabicyclo[3.2.1]oct-3-yl)-1-isopropyl-2-oxo-1, 2-dihydro-3-quinolinecarboxamides were synthesized. The 5-HT4 receptor agonistic activity was evaluated using the isolated guinea pig ileum preparation. Of the compounds synthesized, N-(endo-8-(3-hydroxypropyl)-8-azabicyclo[3.2.1]oct-3-yl)-1-isopropyl-2-oxo-1, 2-dihydro-3-quinolinecarboxamide (15a, TS-951) exhibited the most potent serotonin 5-HT4 receptor agonistic activity. This compound had a high affinity for the serotonin 5-HT4 receptor althought it had no affinities for other broad spectrum receptors. Furthermore, it remarkably enhanced gastrointestinal motility in conscious fed dogs without unfavorable effects that non-selective serotonin 5-HT4 receptor agonist has. TS-951 may be useful in improving gastrointestinal dysfunction.

The reaction of benzyne with several kinds of dithiolactones, such as β-dithiolactone (9), benzothiophene-1-thione (13), l,2-dithiolane-3-thione (20), and 3,3,5,5-tetramethyl-4-thioxothiolane-2-thione (7), afforded benzo-1,3-dithioles in moderate to good yields, whereas the reaction of benzyne with γ-thionolactone (16) gave γ-lactone and diphenyl disulfide.

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.

The reaction of selenofenchone (3a) with propiolic acid in refluxing chloroform produced selenodioxenone (4) along with rearranged product (5b), while 5b was obtained in almost quantitative yield under solvent-free conditions. In the presence of Lewis acid, selenofenchone 3a reacted with methyl propiolate to afford corresponding rearranged adduct (7).

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...

The reaction of dimethyl(methylthio)sulfonium trifluoromethanesulfonate (DMTST) with o-allylphenol gave 2-methylthiomethyl-2,3-dihydrobenzofuran in 97% yield. The reaction of DMTST with N-tosyl-o-isopropenylanilide followed by the addition of aq sodium carbonate afforded N-tosyl-3-methylindole in 88% yield, whereas N-tosyl-o-vinylanilide afforded N-tosylindoline in 85% yield.

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.

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.

An efficient and practical procedure for the synthesis of esonarimod, (R,S)-2-acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanoic acid (1), a new antirheumatic drug, has been developed. The intermediate, 2-methylene-4-(4-methylphenyl)-4-oxobutanoic acid (2), was prepared by Friedel-Crafts acylation of toluene with itaconic anhydride (3) in the presence of aluminum trichloride and nitrobenzene in 63% yield without silica gel column purification. Compound 1 was prepared by Michael addition of 2 with thioacetic acid (4) in 74% yield. Overall, 1 was obtained in 47% yield from 3. The structures and synthetic mechanisms of by-products (five compounds) of 2 were also clarified.

A series of N-azabicycloalkyl-1-alkyl-2-oxo-1, 2-dihydro-3-quinolinecarboxamides were synthesized and tested for serotonin 5-HT4 receptor-stimulating effects in the regulation of electrically-evoked contraction in guinea pig muscle. Among them, N-azabicycloalkyl-1-isopropyl-2-oxo-1, 2-dihydro-3-quinolinecarboxamide (8c, 9c, 10c, 11c, 12c) exhibited potent serotonin 5-HT4 receptor-stimulating activity. The most potent compound, N-(endo-8-methyl-8-azabicyclo[3.2.1]oct-3-yl)-1-isopropyl-2-oxo-1, 2-dihydro-3-quinolinecarboxamide (8c, ED50=36.3 nM), was seven times as active as cisapride, while 8c had no affinity for 5-HT1A, 5-HT1D, D2, muscarinic M2 or muscarinic M3 receptors even at 10μM. Compound 8c stimulated digestive tract motility in conscious fed dogs (1.0 mg/kg p.o.).

The reaction of pivalophenones with tetraphosphorus decasulfide afforded cis- and trans-3,5-di-tert-butyl-3,5-diaryl-1,2,4-trithiolanes, which equilibrated to give other isomers in refluxing toluene via thiopivalophenones and thiopivalophenone S-sulfides.