Ti-<i>Crossed</i>-Claisen Condensation between Carboxylic Esters and Acid Chlorides or Acids: A Highly Selective and General Method for the Preparation of Various β-Keto Esters
作者:Tomonori Misaki、Ryohei Nagase、Kunshi Matsumoto、Yoo Tanabe
DOI:10.1021/ja043833o
日期:2005.3.9
condensation between a 1:1 mixture of carboxylic esters and acid chlorides promoted by TiCl4-Bu3N-N-methylimidazole proceeded successfully to give various beta-keto esters in good yields with excellent selectivities (19 examples, approximately 48-95% yield; cross/self-selectivity = approximately 96/4-99/1). The present method was extended to the condensation between a 1:1 mixture of carboxylic acids and carboxylic
由 TiCl4-Bu3N-N-甲基咪唑促进的羧酸酯和酰氯的 1:1 混合物之间的 Ti-crossed-Claisen 缩合成功地以良好的收率和优异的选择性得到各种 β-酮酯(19 个例子,大约 48-95 % 产率;交叉/自选择性 = 约 96/4-99/1)。本方法扩展到羧酸和羧酸酯的 1:1 混合物之间的缩合(六个实施例,产率约 70-92%;交叉/自选择性 = 约 91/9-99/1)。为了证明目前两种 Ti 交叉克莱森缩合的效用,我们对两种天然、代表性和有用的香水顺式茉莉酮和 (R)-麝香酮进行了几次有效的短步合成。