Diastereoselectivity in the SE2? reaction of chiral pentadienylsilanes: a test for the relative importance of steric and electronic effects
作者:Ian Fleming、Graeme R. Jones、Nicholas D. Kindon、Yannick Landais、Colin P. Leslie、Ian T. Morgan、Stefan Peukert、Achintya K. Sarkar
DOI:10.1039/p19960001171
日期:——
5E)-(hepta-3,5-dien-2-yl)dimethyl(phenyl)silane 9, (3Z,5E)-(hepta-3,5-dien-2-yl)trimethylsilane 13, (4Z,6E)-(2-methylocta-4,6-dien-3-yl)dimethyl(phenyl)silane 14 and (4Z,6E)-(2-methylocata-4,6-dien-3-yl)trimethylsilane 17 undergo Lewis acid catalysed reactions with isobutyraldehyde and its dimethyl acetal stereospecifically anti with surprisingly high levels of stereoselectivity, ca. 90:10. The pentadienylsilanes
的纯手性pentadienylsilanes(3 Ž,5 ë) - (庚-3,5-二烯-2-基)二甲基(苯基)硅烷9,(3 Ž,5 ë) - (庚-3,5-二烯-2-基)三甲基硅烷13,(4 Z,6 E)-(2-甲基辛基-4,6-二烯-3-基)二甲基(苯基)硅烷14和(4 Z,6 E)-(2-甲基羰基-4, 6-二烯-3-基)三甲基硅烷17与异丁醛及其二甲基乙缩醛发生立体定向抗路易斯酸催化反应,其立体选择性出乎意料地高。90:10。戊二烯基硅烷(3 Z)-六-3,5-二烯-2-基二甲基(苯基)硅烷20aa,(4 Z)-(2-甲基庚-4,6-二烯-3-基)二甲基(苯基)硅烷20ab,(3 Z)-(六-3,5-二烯-2-基)-三甲基硅烷20ba和(2 Z) - (1- phenylpenta -2,4-二烯基)三甲基硅烷20Bc的经历偶极环加成到2,2-二甲基丙腈的氧化区域选择性地在末端双键和