First example of reversal of normal stereoselectivity in the intramolecular Pauson-Khand reaction
作者:Joseph A. Casalnuovo、Robert W. Scott、Eric A. Harwood、Neil E. Schore
DOI:10.1016/0040-4039(94)88010-7
日期:1994.2
Stereoselectivity favoring exo substituent orientation in the intramolecular Pauson-Khand reaction of 3-methyl-4-hydroxy-1,6-heptenynes to form bicyclo[3.3.0]octenones is affected by the relative stereochemistry at C3 and C4. Cycloaddition of one stereoisomer of 3,5-dimethyl-4-propargyl-1,6-heptadiene gives predominantly the bicyclo[3.3.0]octenone isomer containing both substituents in more hindered
在C3和C4处的相对立体化学影响在3-甲基-4-羟基-1,6-庚炔的分子内Pauson-Khand反应中形成双环[3.3.0]辛烯酮的立体选择性,这有利于exo取代基的取向。的一种立体异构体的环加成3,5-二甲基-4-炔丙基-1,6-庚二烯主要给出包含在多种位阻的取代基都将双环[3.3.0] octenone异构体内取向。提出了基于金属环形成之前的构象偏好的影响的解释。