Catalyzed Selective Direct α- and γ-Alkylation of Aldehydes with Cyclic Benzyl Ethers by Using T+BF4− in the Presence of an Inexpensive Organic Acid or Anhydride
作者:Heinrich Richter、Renate Rohlmann、Olga García Mancheño
DOI:10.1002/chem.201101786
日期:2011.10.4
The cross dehydrogenative coupling (CDC) of cyclic benzyl ethers with aliphatic and α,β‐unsaturated aldehydes has been developed. The mild reaction conditions, in which an N‐oxoammonium salt derived from TEMPO (2,2,6,6‐tetramethyl‐1‐piperidinoxyl) is employed as the oxidant in combination with a Cu catalyst, allow the use of relatively redox‐unstable aldehydes under oxidative CDC conditions. The addition
已开发出环状苄基醚与脂族和α,β-不饱和醛的交叉脱氢偶联(CDC)。在温和的反应条件下,将来自TEMPO的N-氧铵盐(2,2,6,6-四甲基-1-哌啶氧基)与Cu催化剂一起使用作为氧化剂,允许使用相对氧化还原不稳定的在氧化CDC条件下生成醛。加入催化量的三氟乙酸(TFA)或Ac 2O促进反应并增加效率和选择性。与使用脂肪族醛获得的预期的α-烷基化相反,α,β-不饱和醛优先导致更具挑战性的γ-烷基化产物。通过合成异铬烷衍生的生物活性化合物(如多巴胺拮抗剂sonepiprazole)证明了开发的方法的实用性。