FREMGANGSMÅDE TIL FREMSTILLING AF UMÆTTEDE TRIFLUORMETHANSULFONAT-STEROID-DERIVATER

摘要

Disclosed is a method for the conversion of a compound of formula 3 to a compound
of formula 4, wherein R is an acetyl group or an alcohol-protecting group. The process involves reacting 3 with a triflating agent in the presence of a nicotinate (3-pyridinecarboxylate) of a C1-C4 alcohol, preferably methyl nicotinate (methyl 3-pyridinecarboxylate) or ethyl nicotinate (ethyl 3-pyridinecarboxylate), to give 4. The method can be conveniently used in a process for the preparation of Abiraterone or Abiraterone acetate.