The Applications Of A-Cyanoketene Dithioacetal In The Baylis-Hillman Reaction

Baylis-Hillman reaction, as one of the high efficient carbon-carbon bond formationreaction, meets the requirements of atom economy and high levels of selectivity, and themultifunctional B-H adducts are versatile building blocks for the synthesis of variousbiologically active compounds and natural products. Although the research about B-Hreaction was well described, the investigation on β-substituted nuclephile and the applicationof ketone remained few explored. Moreover, few reports were focus on the special doubleB-H reaction.α-Oxo ketene dithioacetals are a kind of versatile intermediates in organic synthesis.Many compounds with special structures can be constructed from these intermediates, due totheir special synthesis and the construction of natural products.In our recent research on the synthetic applications of α-acetyl ketene S,S-acetals andtheir analogues, a series of α,β-unsaturated compounds with electron-donating alkylthiogroups and electron-withdrawing carbonyl groups were obtained in high yields. Beside, inYin's research, the double B-H type adducts and aza-B-H type adducts were obtained. In thispaper, we describe here a very reactive nucleophile, α-cyanoketene dithioacetal which canreact with aldehydes/ketones under very mild condition to provide double B-H adducts. Themain results are listed as follows:1,Four of α-amino acyl ketenedithioacetles were synthesized. Being α-functionalized,after the dehydration, the reaction conditions optimized, two of α-cyanoketene dithioacetalwere obtained in high yield.2,Seventeen of highly functionalized double B-H type adducts were synthesized byperforming the Baylis-Hillman reaction of α-cyanoketene dithioacetal with arylaldehydes inthe presence of TiCl4 in acetonitrile at room temperature in moderate to excellent yield.3,Five of double B-H type adducts were synthesized between α-cyanoketene dithioacetaland less active ketones in the presence of TiCl4 at room temperature. However it is reportedthat simple ketones require high pressure to undergo B-H reaction. Therefore the specialcharacters of α-cyanoketene dithioacetal extend the applications of simple ketones in B-Hreaction.In this paper, twenty-four new products were synthesized and characterized via IR, 1HNMR and 13C NMR.