¦¡-carbonyl Disulfide Reduction Enone Reduction Reaction

a-Oxo ketenedithioacetals are a kind of versatile intermediates in organic synthesis. It can be used in aromatization, cyclization, reduction, condensation reactions and it can construct many compounds with special structures for their special stereoelectronic effect from the alkylthio functionalities. So it has been applied in organic synthesis and the composition of natural products.The reduction reaction of a-oxo ketenedithioacetals is emphasized in this paper. The regioselectivity and influencing effectors of the reduction reaction performed with sodium borohydride in alcohol were discussed. The dithioorthoesters, a, b-unsaturated thiol esters and b-(bis-methyl sulfanyl-methylene)-pentane-l,4-diene were thus synthesized via the reduction products 3-(bis-alkylsulfanyl-methylene)-pentane-l,4-diol (7) catalyzed by oxalic acid in different solvents. The reaction conditions were also optimized in the experiments. 1,3-Carbonyl transposition reaction was carried out successfully. In these reactions the different alkylthio groups possess different activities and so affact the results dramatically. Specially, the 1,3-carbonyl transposition reaction of cyclic alkylthio group was achieved successfully at first. The mechanism of the reduction reaction is studied deeply and the reaction condition is optimized. The mechanisms of the synthesis of dithioorthoesters and a, p-unsaturated thiol esters were studied by the identified constructure of the intermediates. The crystal diffraction of compound 7a identified its configuration and provided the basis of the machanism of the reduction reaction.Another part of the paper studied the synthetic application of compound l-[l,3]dithian-2-ylidene-l-nitro-propan-2-one (6). Some of its reactions with diamines and hydrazines were discussed. a-Nitro-N,N-ketene acetals were obtained by treating compound 6 with diamines and substituted pyrazoles were obtained by reacting compound 6 withhydrazines. The reaction mechanism was discussed.The vista for the futher work about dithioorthoesters and a, P-unsaturated thiol esters was based on correlative documents.This paper reports forty new compounds that were confirmed by IR, 'HNMR and MS. The configuration of compound 7a was confirmed by X-ray diffaction.