Nickel-Catalyzed Intermolecular 4+3+2 Cycloaddition of Ethyl Cyclopropylideneacetate and Dienynes: Synthesis of Nine-membered Ring Products

摘要

Medium-sized carbocycles are frequently incorporated in various natural products, and the development of an efficient method to construct the carbocycles is an important issue in organic synthesis. Some transition metal-catalyzed cycloaddition reactions provided unique and promising solutions for the preparation of the medium-sized rings. Recently, we examined the cycloaddition reactions of ethyl cyclopropylideneacetate (1) wim unsaturated hydrocarbons in the presence of nickel catalyst and disclosed the high and unique reactivity of 1. For example, [3+2+2] cycloaddition between 1 and alkynes gave cycloheptadienes in good yield. The [4+3] cycloaddition between 1 and conjugated diene gave the cycloheptene derivative. In this context, we discovered that nine-membered carbocycles were synthesized by [4+3+2] cycloaddition of 1 and dienynes (eq. 1). In this presentation we report the [4+3+2] cycloaddition of 1 and dienynes with nitrogen tethers.