碳酸诱导的空间位阻酮的 Mukaiyama 羟醛缩合反应。

Carbon acid induced Mukaiyama aldol type reaction of sterically hindered ketones.

机构信息

School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan.

出版信息

J Org Chem. 2010 Aug 6;75(15):5375-8. doi: 10.1021/jo100915e.

PMID:20578756

Abstract

1,1,3,3-Tetrakis(trifluoromethanesulfonyl)propane (Tf(2)CHCH(2)CHTf(2)) is one of the most effective Brønsted acid precatalysts for the Mukaiyama aldol type reactions of sterically hindered ketones. By using Tf(2)CHCH(2)CHTf(2) in a range from 0.5 to 2.0 mol %, the vinylogous Mukaiyama aldol reaction of alpha-substituted cyclohexanones with 2-silyloxyfurans smoothly proceeded to give the aldol products in excellent yield without the loss of diastereoselectivity. Under similar conditions, acyclic ketene silyl acetals also performed as nice nucleophiles toward sterically hindered ketones. These findings suggest that Tf(2)CHCH(2)CHTf(2) induced Mukaiyama aldol type reactions can overcome the steric hindrance between reaction sites.

摘要

1,1,3,3-四（三氟甲烷磺酰基）丙烷（Tf₂CHCH₂CHTf₂）是用于 Mukaiyama 缩醛型反应的最有效的 Brønsted 酸前催化剂之一，可用于空间位阻酮。通过使用 Tf₂CHCH₂CHTf₂的范围从 0.5 到 2.0 摩尔％，α-取代的环己酮与 2-硅氧基呋喃的烯醇化 Mukaiyama 缩醛反应顺利进行，而不会失去非对映选择性。在相似的条件下，无环酮亚胺硅基缩醛也作为亲核试剂对空间位阻酮进行反应。这些发现表明，Tf₂CHCH₂CHTf₂诱导的 Mukaiyama 缩醛型反应可以克服反应位点之间的空间位阻。