Synthesis of alpha-amino tetrahydropyranyl-, tetrahydrothiopyranyl-, 4- and 3-piperidinyl-phosphonic acids via phosphite addition to iminium ions

摘要

alpha-Amino cyclobutyl-, cyclopentyl-, cyclohexyl- and 4- and 3-heterocyclohexyl-phosphonates were efficiently prepared from carbocyclic and heterocyclic ketones, by nucleophilic addition of phosphite to the iminium ion formed by in situ condensation of these ketones with benzylic amines. Cleavage of the benzyl groups and acidic hydrolysis of the resulting a-amino heterocyclohexyl-phosphonates gave, in a three-step sequence from ketones, new 4- and 3-heterocyclobexyl-phosphonic acids. (c) 2006 Elsevier Ltd. All rights reserved.