Organocatalytic Asymmetric Conjugate Addition of N-Heterocycles to Enals

Significance

An organocatalytic asymmetric conjugate addition of N-heterocycles to α,β-unsaturated aldehydes has been described. The N-heterocycles investigated were 1,2,4-triazole, 5-phenyl tetrazole, 1,2,3-benzotriazole, and 1,2,3-triazole. Proline-derived catalyst 1 in combination with PhCO₂H has been found to be effective for this reaction. With 10 mol% of the catalyst 1 moderate to high yields (45-87%) and high enantioselectivities (er = 90:10 to 97:3) were obtained for different alkyl and alkenyl substituted enals.