Picolylamine as an organocatalyst template for highly diastereo- and enantioselective aqueous aldol reactions

Abstract

A pyridine based 1,2-diamine containing only one stereogenic center has been identified for fast aldol reactions (16–48 h). Using 2–5 mol% of (R)- or (S)-PicAm-2, cyclohexanone (3.3 equiv) readily undergoes aldol reactions with o-, m-, and p-substituted aromatic aldehyde partners (limiting reagent), including the poor electrophile 4-methylbenzaldehyde (95–99% ee). Furthermore, functionalized cyclic ketone substrates have been converted into four aldol products 9–12 using the lowest catalyst loading (5.0 mol%) to date with the highest yield and enantioselectivity.