Generation of Alkylidene Carbenes through Tetrazole Fragmentation: Recent Advances and Applications in Organic Synthesis

Abstract

AbstractTetrazole fragmentation under mild conditions from 5-hydroxyalkyl-1H-tetrazoles (HATs) or cyanophosphates (CPs) readily generates the corresponding alkylidene carbenes, which undergo [1,2]-rearrangements or [1,5]-C–H insertions to yield one-carbon homologous alkynes or five-membered unsaturated carbocycles, respectively. Furthermore, azido-HATs and 2-cyanoazetidines afford propargylic and homopropargylic amines, respectively, via [1,2]-rearrangement of the corresponding aminoalkyl alkylidene carbenes. These reactions are successfully applied for the synthesis of various biofunctional molecules. This short review summarizes the progress made on this methodology over the last decade.1 Introduction2 Early Studies3 Tetrazole Fragmentation of HATs, Azido-HATs, and 2-Cyanoazetidines4 HAT Synthetic Methods5 Tetrazole Fragmentation from CPs6 Summary and Perspective