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48.1.3.1.3 Method 3: The Wolff–Kishner Reduction (Reduction of Aldehydes and Ketones via Hydrazones)

DOI: 10.1055/sos-SD-048-00026

Wicha, J.Science of Synthesis, (200948111.

Base-induced fragmentation of hydrazones 21 or the corresponding semicarbazones 22, first reported by Kishner[‌103‌] and Wolff[‌104‌] (the WolffKishner reduction), provides a convenient method for obtaining hydrocarbons from aldehydes or ketones (Scheme 25). Synthetic applications of the WolffKishner reduction have been extensively reviewed in HoubenWeyl, Vol.5/1a, pp 251, 544 and Vol.7/2b, p1999 and in other compendia.[‌6‌,‌105‌‌107‌] In the original Kishner procedure,[‌103‌] the transformation is accomplished by dropping a hydrazone onto hot potassium hydroxide, with which some crushed platinized porous plate has been mixed. In the method reported by Wolff,[‌104‌] a hydrazone or semicarbazone and sodium ethoxide are heated in a sealed tube at 180°C. It has been proven that the semicarbazone undergoes hydrolysis or alcoholysis with formation of the corresponding hydrazone in the initial step.

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