Science of Synthesis

Nicasio, M. C.; Belderrain, T. R., Science of Synthesis: C-1 Building Blocks in Organic Synthesis, (2014) 2, 145.

General Introduction

Alkylidene carbenes are commonly employed in organic synthesis as intermediates;[‌1‌–‌3‌] see also Houben–Weyl, Vol. E 21, p 1127. Among the variety of chemoselective transformations developed with these species, C—H insertion has become very useful as a synthetic tool due to its applicability to the generation of five-membered carbocyclic or heterocyclic systems with a stereochemically defined quaternary carbon center,[‌1‌–‌3‌] as initially suggested by the works of Gilbert[‌4‌–‌10‌] and Ohira.[‌11‌,‌12‌] One of the most important methods for the formation of alkylidene carbenes consists of the treatment of a diazo compound, i.e. a (diazomethyl)phosphonate[‌4‌–‌10‌] or diazo(trimethylsilyl)methane (TMSCHN2),[‌13‌,‌14‌] with a base, and subsequent alkenation of a carbonyl compound (Wittig–Horner reaction[‌15‌] or Peterson elimination[‌16‌]), followed by decomposition of the resulting diazoalkene (‌Scheme 1‌).

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References