A new and efficient method for the synthesis of rocuronium bromide

Rocuronium bromide has been used as an aminosteroid non-depolarizing neuromuscular blocker and muscle relaxant. In this work, a new and efficient route for preparing a key intermediate 2β-(4-morpholinyl)-16β-(1-pyrrolidinyl)-5α-androstan-3α,17β-diol (6) was developed through a ring-opening of epoxide followed by introducing and pyrrolidine. Compound 6 can easily provide rocuronium bromide and the overall yield of compound 6 in 5 steps increased to 57.8%, which was higher than currently reported methods. Extraordinarily, this method would avoid the generation of disubstituted impurities E and F which are difficult to remove.