2-Oxyallyl synthons 4 + 3 cycloaddition reactions

The main research efforts in transition metal mediated [3 -1- 2] cycloaddition can be categorized into the development of three important types of C3 synthon dimethylenemethane, 2-oxyallyl, and trimethy-lenemethane. This review summarizes some recent achievements up to the first quarter of 1989, and centers around these three synthons. Emphasis will be placed on the chemo-, regio- and stereo-selectivity of these reactions, their preparative aspects, and their synthetic potential. 

There are many synthons designed to exhibit the reactivity of the 2-oxyallyl cation and participate in the [4+3] cycloaddition as the dienophile. This review will focus on those precursors that are derivatives of enolsilanes. This subgroup has been selected for discussion due to the recent examples in the literature, and the opportunities they have provided in asymmetric synthesis and total synthesis, and have clarified and impacted the mechanistic course of this reaction. 

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