Bifunctional chiral auxiliaries 7: Aldol reactions of enolates derived from 1,3-diacyl-imidazolidine-2-thiones and 1,3-diacylimidazolidin-2-ones
作者:Stephen G. Davies、Alison J. Edwards、Gary B. Evans、Andrew A. Mortlock
DOI:10.1016/s0040-4020(01)89691-5
日期:——
Dibutylboron enolates of 1,3-diacylimidazolidine-2-thiones and 1,3-diacylimidazolidin-2-ones undergo highly syn-stereoselective aldol reactions with aldehydes to allow elaboration of both acyl sidechains. The reaction is proposed to occur via sequential enolisation rather than via a bisenolate and the stereochemistry of the product was elucidated by both X-ray crystallography and reductive cleavage
烯醇化物二丁基1,3- diacylimidazolidine -2-硫酮和1,3- diacylimidazolidin -2-酮离岗高度顺式与醛-stereoselective羟醛缩合反应,从而允许其酰基侧链的阐述。建议该反应通过顺序烯醇化而不是通过二烯酸酯来进行,并且该产物的立体化学通过X射线晶体学和同手性羟醛产物的还原裂解来阐明,以给出(1 R,2 S)-1-苯基- 2-甲基丙烷-1,3-二醇。相比之下,三氟甲磺酸锡(II)介导的醛醇缩合反应仅导致两个酰基侧链之一发生反应,并展现出相反的对面立体选择性。