A novel process for the preparation of [(R,S)/ (S,R)] and [(S,S)/ (R,R)] chroman epoxides, key intermediates in the synthesis of Nebivolol (original) (raw)

International Journal of Bioassays

A novel, cost effective, scalable process for the preparation of chroman epoxides starting from 4-fluorophenol is described. The highlights of the process are single step O-acylation, fries rearrangement, one pot synthesis of claisen condensation, cyclization, reduction, epoxidation with over all yield of 50.9% [(R,S)/(S,R)]-chroman epoxide-A is 33.9% and [(S,S)/(R,R)]-chroman epoxide-B is 17%.