Microwave assisted Petasis boronic-Mannich reactions

We have used a design of experiments (DOE) approach to optimise rapidly a set of microwave assisted conditions for the Petasis reaction. The optimal conditions involved the microwave heating of the reaction components in dichloromethane (1 M concentration) at 120 °C for 10 min in a focussed microwave (CEM Explorer). These conditions were successfully applied to a range of Petasis reactions employing either glyoxylic acid or salicylaldehyde as the carbonyl component along with a number of aryl/heteroaryl boronic acids and amine components.