Organocatalytic anti-Selective Direct Mannich Reaction

Significance

Several aldehydes (1) and α-amino esters (2) were transformed to the corresponding β-amino aldehydes in an anti-selective manner by using chiral amino sulfonamides (3) in low catalyst loadings (2 mol%). It turned out that the presence of the trifluoromethyl group on the sulfonamide moiety was necessary to achieve good yields as well as good anti/syn ratios and nearly complete enantioselectivity. For more sterically hindered aldehydes (e.g., R¹ = i-Pr) higher catalyst loading (5 mol%) was required. No self-aldolization products were formed.