NEW SYNTHESIS OF (+)-(S)-HALOTHANE

A new synthesis of non-racemic halothane (1-bromo-1-chloro-2,2, 2-trif luoroethane) is reported. The stereospecificity of the key reaction, d ecarboxylation of a salt of optically enriched 1-bromo-1-chloro-2,2,2- trinuoropropionic acid to give halothane, is shown to be highly depend ent on the nature of the cation. When the cation is trialkylammonium, a high level of stereospeciticity is observed. (C) 1996 Wiley-Liss, In c.