[4+2]‐Cycloadditions of Phosphinodiazoalkanes: Synthesis of 1,2,4‐λ⁵‐Diazaphosphinines

Abstract

Diazoalkanes become partners for [4 + 2]-cycloadditions through a phosphinosubstituent on the diazo carbon. This is illustrated by the reactions of 1, R  OMe, Ph, with 2, R′  OMe, Ph, leading to the diaza-λ5-phosphinines 3. In contrast, the diazo compounds 1 react with tBuCP in a “normal” [3 + 2]-cycloaddition.