Methods for the Cleavage of Allylic and Propargylic C–N Bonds in Amines and Amides – Selected Alternative Applications of the 1,3‐Hydrogen Shift

Abstract The aim of this article is to provide an updated review on the various methodologies that allow allylic C–N bonds (and by extension propargylic C–N bonds) to be cleaved. Since selectivity is crucial for synthetic planning, as far as possible, the relative reactivity of the various allylic groups is examined, and the discrimination between O ‐allyl and N ‐allyl derivatives is discussed. A special development is devoted to reactions leading to enamines through a 1,3‐hydrogen shift, even though some of these reactions were not originally performed for the purpose of cleaving the N ‐allyl bond. Some selected applications are discussed. In addition to preparative deprotection methods, reactions such as the enzyme‐mediated cleavage of allylic C–N bonds are also mentioned, although these reactions may not have any practical synthetic interest at the moment. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)