Silicon as a directing group in the phosphine-catalyzed [2 + 3]-cycloaddition of aryl allenones with electron-deficient olefins

摘要

This Communication describes a highly efficient phosphine-catalyzed [2 + 3]-cycloaddition reaction using α-trimethylsilyl-substituted aryl allenones and electron deficient oletins; both good yields and good asymmetric induction were obtained.rnFunctionalized five-membered rings are featured widely in many drugs and natural products. Accordingly, much effort has been directed towards the development of new synthetic methods for their construction. Among the methods available, the synthesis of functionalized cyclopentenes via [2 + 3]-cycloaddition reactions using allenoates, electron deficient olefins and catalytic amounts of phosphine, first reported by Lu and Zhang in 1995, has been shown to be one of the most powerful methods, and the products can be easily derivatized into highly functionalized cyclopentanes. In recent years, highly asymmetric versions of this reaction have also emerged. Furthermore, this method has also been applied to the total synthesis of several natural products. A variation of this method via a [4 + 2] process to construct six-membered rings has also been elegantly demonstrated by Kwon and Fu.