Chiral polyamines from reduction of polypeptides: asymmetric pyridoxamine-mediated transaminations

BH3•THF can reduce polypeptides to polyamines with retention of chirality. The resulting polyamines are intriguing general platforms for asymmetric catalysis, given the diverse structures available and their relative ease of synthesis. We have constructed a number of chiral pyridoxamine catalysts based on reduced peptides. These compounds transaminate α-ketoacids with moderate to good enantioselectivity, while their peptidyl counterparts show almost no chiral induction.