Iron‐Catalyzed Four‐Component Reaction for the Synthesis of Protected Primary Amines

Abstract

Abstract The first catalytic four‐component reaction (4CR) of carbonyl compounds with alkyl chloroformate, HMDS and Et 3 SiH has been developed to produce protected primary amines by a novel tandem nitrogen protection/direct reductive amination of carbonyl compounds. In the presence of 5 mol‐% of an iron(II) salt, a wide variety of aldehydes and ketones were transformed into their corresponding protected primary amines in good to excellent yields under “pure” multicomponent reaction (MCR) conditions. This chemistry was further extended to masked carbonyl compounds such as acetals, ketals, and vinyl ethers. When compared with previous methods to prepare protected primary amines from a large excess of ammonia or ammonium salts, this 4CR not only saved at least one step of synthetic manipulation, but also utilized nearly stoichiometric nitrogen and hydrogen sources and avoided the formation of (protected) secondary amines. Additional advantages of this protocol include broader substrate scope, the use of an inexpensive and environmentally friendly catalyst, and mild reaction conditions.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)