Powerful Ti-Crossed Claisen Condensation between Ketene Silyl Acetals or Thioacetals and Acid Chlorides or Acids
作者:Akira Iida、Syogo Nakazawa、Tomohito Okabayashi、Atsushi Horii、Tomonori Misaki、Yoo Tanabe
DOI:10.1021/ol0619361
日期:2006.11.9
[Structure: see text] A powerful Ti-crossed Claisen condensation between ketene silyl acetals (KSAs) and acid chlorides was successfully performed to give alpha-monoalkylated esters and thermodynamically unfavorable (less accessible) alpha,alpha-dialkylated beta-keto esters in good yield (46 examples; 41-98% yield). A closely related reaction between ketene silyl thioacetals (KSTAs) and acid chlorides also
[结构:参见正文]成功地进行了乙烯酮缩醛缩醛(KSAs)与酰氯之间强力的Ti交联的Claisen缩合反应,制得的α-单烷基酯和热力学上不佳(难得)的α,α-二烷基β-酮酯收率(46个实施例; 41-98%收率)。乙烯酮甲硅烷基硫缩醛(KSTA)和酰氯之间的密切相关的反应也顺利进行,得到α-单烷基化和α,α-二烷基化的β-酮硫代酯(21个实例;产率61-97%)。本协议扩展到KSA与羧酸的直接缩合(14个实例;产率71-97%)。