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.