Caglioti reaction

What is Caglioti reaction?

In 1962, Caglioti was the first to report a reaction that converts a carbonyl group (ketones or aldehydes) into a methylene group or an olefinic moiety with a vicinal carbon. This is achieved by treating the corresponding p-tosylhydroazones of the ketones or aldehydes with a hydride base, such as diborane (B2H6), lithium hydride (LiH), sodium borohydride (NaBH4), lithium aluminium hydride (LiAlH4), sodium cyanoborohydride (NaBH3CN), and catecholborane.

Caglioti reaction - general reaction scheme - Caglioti reduction - Caglioti alkene synthesis
Caglioti reaction
  • R1 = alkyl, aryl
  • R2 = H, alkyl, aryl
  • Ts = p-CH3C6H4SO2
  • Hydride = LiH, LiAlH4, NaBH4, NaBH3CN, B2H6, catecholborane, etc. (see acronyms)

This reaction is commonly referred to as the Caglioti reaction, although it is occasionally known as the Caglioti reduction or Caglioti alkene synthesis.

The Caglioti reaction is a viable substitute for conventional methods (for conversion of carbonyls into methylene groups) such as the Wolff-Kishner reduction, Huang-Minlon modification, and Clemmensen reduction. However, it is more closely associated with the Bamford-Stevens reaction.

Like the Wolff-Kishner reduction and Clemmensen reduction, this reaction is advantageous for converting carbonyl compounds into hydrocarbons and olefins.