Formation of enamines by alkylation of imines

Abstract

cf. CA 64, 12473c. With ice-cooling, 1 equiv. alkylating agent was added to one equiv. of the imine in 1M soln. in a solvent in the presence of NaH to give both N- and C-alkylated products. The following summarizes the date (imine, solvent, alkylating agent, % unreacted imine, % N-alkylated product, % C-alkylated product, % polyalkyl product): PhMeC:NH (I), (EtOCH2)2 (II), Et3OBF4 (III), 8, 88, 4, -; I, II, Et2SO4, 9, 49, 42, -; I, II, EtI (IV), 5, 5, 90, -. In the following, NaNH2 replaced NaH (same data given): cyclohexanon imine (V), hexamethylphosphoric triamide (VI), III, 29, 53, 18, -; V, VI, Me2SO4 (VIa), 11, 75, 10, 4; V, VI, IV, 15, 17, 56, 12; Et2C:NH (VII), VI, III, 26, 29, 42, 3; VII, VI, VIa, 17, 57, 26, 0; and VII, VI, IV, 20, 0, 71, 9. [on SciFinder (R)]