Stereoselective functionalisation of SuperQuat enamides: asymmetric synthesis of homochiral 1,2-diols and α-benzyloxy carbonyl compounds
作者:Caroline Aciro、Stephen G. Davies、A. Christopher Garner、Yutaka Ishii、Min-Suk Key、Kenneth B. Ling、R. Shyam Prasad、Paul M. Roberts、Humberto Rodriguez-Solla、Catherine O'Leary-Steele、Angela J. Russell、Hitesh J. Sanganee、Edward D. Savory、Andrew D. Smith、James E. Thomson
DOI:10.1016/j.tet.2008.07.012
日期:2008.9
1′-m-chlorobenzoyl-2′-hydroxy derivatives (≥96% de) generates homochiral 1,2-diols in ≥96% ee. Alternatively, regioselective lithiation of the enamide at C(1′) with tBuLi followed by reaction with an aromatic aldehyde and in situ O-benzylation generates a 1′-(benzyloxy-aryl-methyl) substituted enamide with high diastereoselectivity. Subsequent oxidative cleavage of the enamide CC bond with NaIO4/RuCl3 followed by
衍生自SuperQuat(S)-4-苯基-5,5-二甲基-恶唑烷-2--2-的SuperQuat(S)-4-苯基- (E)-和(Z)-酰胺在用二甲基二环氧乙烷处理后会经历高度非对映选择性的环氧化反应。随后环氧化物开环与元经由立体选择性小号氯苯甲酸前进Ñ 1型过程中,随着结构的保持力,以得到相应的1'-米-chlorobenzoyl -2'-羟基衍生物。用m CPBA处理SuperQuat酰胺可在一锅中完成这一两步转化。分离的1'- m的还原裂解-氯苯甲酰基-2'-羟基衍生物(de≥96%)在ee≥96%中产生均手性1,2-二醇。备选地,在t( BuLi )下在C(1')处烯酰胺的区域选择性锂化,然后与芳族醛反应并原位O-苄基化产生具有高非对映选择性的1'-(苄氧基-芳基-甲基)取代的酰胺。随后用NaIO 4 / RuCl 3氧化烯酰胺CC键,然后甲醇水解所得的N-酰基片段,从而在高ee中提供了O-苄基保护的α-羟基甲基酯。