Stereoselective Synthesis of Nitrogen-Containing Compounds from Enamines

The domino reaction of enamines, electrophiles (N-sulfonylimines, N-tosylisocyanate, or diethyl azodicarboxylate), and trichlorosilane provided trans-amines (trans/cis = > 99:1 to 96:4). Meanwhile, the sequential imino ene-type reaction of enamines and electrophiles/NaBH3CN reduction afforded cis-amines (trans/cis = 1:>99 to 15:85). The reversal of selectivity is discussed on the basis of diastereofacial selection of the plausible iminium ion intermediates. For the domino reaction of cyclic enamines and cyclic imines, high enantioselectivity (er = 95.7:4.3 to 99.9:0.1) was achieved by utilizing chiral Lewis base catalysts.