Reaction Rate Acceleration
Enabled by Tethered Lewis Acid-Lewis Base Bifunctional
Catalysis: A Catalytic, Enantioselective [2+2] Ketene
Aldehyde Cycloaddition Reaction
作者:Yun-Ming Lin、Sridhar Chidara
DOI:10.1055/s-0029-1217332
日期:——
asymmetric [2+2] cycloaddition reaction between ketene and aldehydes rapidly. The LA * ―LB * bifunctional catalyst, a quinine tethered Co(III)―salen complex (5 mol%) catalyzes the [2+2] cycloaddition reaction to produce the C4-substituted β-lactone in uniformly >99% ee and high isolated yields (71―97%). The dramatic rate acceleration, the hallmark of cooperative intramolecular bifunctional catalysis, is achieved
系留路易斯酸-路易斯碱 (LA * ―LB * ) 双功能催化剂可快速促进烯酮和醛之间的不对称 [2+2] 环加成反应。LA * ―LB * 双功能催化剂,一种奎宁束缚的 Co(III)-salen 络合物 (5 mol%) 催化 [2+2] 环加成反应生成 C4 取代的 β-内酯,ee 均匀 >99%,高分离产率 (71-97%)。催化性、对映选择性 [2+2] 环加成反应在醛和未取代的烯酮之间实现了显着的速率加速,这是协同分子内双功能催化的标志。