Sulfonamides of homoproline and dipeptides as organocatalysts for Michael and aldol reactions

Sulfonamides of the non-natural amino acid homoproline and the dipeptide Pro-Phe were synthesised and evaluated for their catalytic activity in Michael and aldol reactions. Sulfonamides of homoproline outperform proline and Pro-Phe in the Michael reaction, whereas sulfonamides of Pro-Phe lead to better results in the aldol reaction. The results of the present study show that the conversion of the carboxylic group of either homoproline or dipeptide Pro-Phe to the bioisosteric acyl sulfonamide group lead to improved organocatalysts. (C) 2008 Elsevier Ltd. All rights reserved.