1,5-Stereocontrol in tin(IV) halide mediated reactions between N- and S-substituted pent-2-enylstannanes and aldehydes or imines
作者:Steven J. Stanway、Eric J. Thomas
DOI:10.1016/j.tet.2012.05.032
日期:2012.7
stannane with benzaldehyde proceeded with some stereoselectivity, 80–90:20–10, in favour of the (3Z)-1,5-syn-diastereoisomer, the yield was low due to a competing Lewis acid catalysed 1,4-elimination. N-Acylamino- and S-acylthio-pent-2-enylstannanes reacted with aldehydes with variable syn/anti-stereoselectivities. Tin(IV) chloride promoted reactions of the 4-(dibenzylamino)pent-2-enylstannane with
(4 S)-4-(二苄氨基)戊-2-烯基(三丁基)锡烷与溴化锡(IV)的金属转移后,生成的三溴化烯丙基锡与醛的反应得到(3 Z)-1,5- syn -5 -(二苄氨基)hex-3-en-1-ols具有优异的ca. 98:2,立体声控制。(4 R)-5-苄硫基-4-甲基戊-2-烯基(三丁基)锡烷与醛类似地反应得到(3 Z)-1,5-抗-6-苄硫基-5-甲基己基-3-en-1 -ols具有87:13立体声控制。尽管(4 R)-4-苄硫基-2-烯基(三丁基)锡烷与苯甲醛的类似反应以一定的立体选择性进行,但80-90:20-10,有利于(3 Z)-1,5- syn-非对映异构体,由于竞争的路易斯酸催化的1,4-消除,收率低。N-酰基氨基-和S-酰基硫代戊-2-烯基锡烷与具有可变的顺/反立体选择性的醛反应。氯化锡促进4-(二苄基氨基)的反应戊-2- enylstannane与1- alkoxycar