A Designer Axially Chiral Amino Sulfonamide as an Efficient Organocatalyst for Direct Asymmetric anti-Selective Mannich Reactions and syn-Selective Cross-Aldol Reactions

作者：Kano Taichi; Yamaguchi Yukako; Maruoka Keiji^*

来源：Chemistry - A European Journal, 2009, 15(27): 6678-6687.

DOI：10.1002/chem.200900267

• aldol reaction
• sulfonamides
• asymmetric synthesis
• Mannich reaction
• organocatalysis

A direct asymmetric Mannich reaction using a novel axially chiral amino sulfonamide (S)-3 that is highly anti- and enantioselective has been developed. For instance, in the presence of a catalytic amount of (S)-3, the reactions between aldehydes and cc-imino esters proceeded smoothly to give anti Mannich products with a significantly higher antilsyn ratio and enantioselectivity than previously possible. By utilizing N-Boc-protected aromatic imines instead of alpha-imino esters, the synthetically useful Boc protecting group and various aromatic or heteroaromatic substituents were installed into the anti Mannich products and consequently the substrate scope of the anti-selective Mannich reaction and the synthetic utility of the anti Mannich products have been expanded. The axially chiral amino sulfonamide (S)-3 has also been successfully applied to asymmetric direct cross-aldol reaction between two different aldehydes. The catalyst (S)-3 has the advantage of giving mainly syn products, whereas proline shows the opposite anti selectivity.

• 出版日期2009