α-Amino Carbanions. Preparation, Metalation, and Alkylation of Enamidines. Synthesis of Piperidine and Pyrrolidine Natural Products and Homologation of Carbonyl Compounds

Article abstract of DOI:10.1021/jo00207a023

Saturated heterocycles, as their tert-butylformamidines, may be transformed into enamidines, by metalation-selenation-elimination.These enamidines are valuable precursors to 2-substituted, 2,4-disubstituted, and 2,4,6-trisubstituted pyrrolidines, piperidines, and perhydroazepines, prepared in a regiospecific manner.The method is demonstrated by the synthsesis of selenopsin A and the red fire ant venom.The use of acyclic enamidines is displayed as a homologation reagent which converts carbonyl compounds to higher alkyl derivatives.