Picolylamine as an organocatalyst template for highly diastereo- and enantioselective aqueous aldol reactions
作者:Thomas C. Nugent、M. Naveed Umar、Ahtaram Bibi
DOI:10.1039/c0ob00049c
日期:——
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
Chiral picolylamines for Michael and aldol reactions: probing substrate boundaries
作者:Thomas C. Nugent、Ahtaram Bibi、Abdul Sadiq、Mohammad Shoaib、M. Naveed Umar、Foad N. Tehrani
DOI:10.1039/c2ob26382c
日期:——
organocatalyst template, a vicinal chiral diamine based on a pyridine-primary amine motif. The addition of cyclohexanone to β-nitrostyrene has many catalyst solutions, but cyclopentanone and isobutyraldehydeadditions continue to be challenging. PicAm-3 (10 mol%) readily allows the Michael addition of cyclopentanone or isobutyraldehyde (5.0 equiv.) to β-nitrostyrene derivatives. By contrast, PicAm-1 (7.0 mol%)