Transition-metal catalyzed synthesis of δ-hydroxy-γ-lactones from bis(trimethylsilyl) ketene acetals and allylic acetates via γ-unsaturated carboxylic acids. Comments on the formation of α-cyclopropyl carboxylic acids
Bis(trimethylsilyl)keteneacetals react with allylic acetates in the presence of Pd(0) complexes to give γ-unsaturated carboxylic acids together with α-cyclopropyl carboxylic acids. The unsaturated acids can be converted catalytically to δ-hydroxy-γ-lactones by the H2O2/MTO system (methyltrioxorhenium) and to butenolides by Pd(II) catalyzed intramolecular cyclization reactions. The structure of two
双(三甲基甲硅烷基)乙烯酮缩醛在Pd(0)配合物的存在下与乙酸烯丙酯反应生成γ-不饱和羧酸与α-环丙基羧酸。H 2 O 2 / MTO系统(甲基三氧or)可将不饱和酸催化转化为δ-羟基-γ-内酯,而Pd(II)催化的分子内环化反应则可将其转化为丁烯化物。这些内酯中的两个的结构已经通过X射线分析确定。将讨论环丙酸的形成机理。
Dimeric Manganese‐Catalyzed Hydroarylation and Hydroalkenylation of Unsaturated Amides
products can be obtained in moderate to good yields, which offers practical access to five- and six-membered lactams. This protocol has predictable regio- and chemoselectivity, excellent functional group compatibility and ease of operation in air, representing a significant step-forward towards manganese-catalyzed C-C coupling.