Triazolopyridines. Part 7. Preparation of bromo-triazolopyridines and -triazoloisoquinolines
Abstract
Bromination of the 7-lithiotriazolopyridines (7) and (10) gave small yields of the 7-bromotriazolopyridines (8) and (11). Some ring opening was observed with the lithium derivative (7); ring opening was a major reaction when bromine reacted with 5-lithiotriazoloisoquinoline (15) or with the 7-trimethylsilyltriazolopyridine (20). Good yields of 7-bromotriazolopyridines (8) and (18) and of 5-bromotriazoloisoquinoline (19) were obtained from the appropriate lithio derivative and dibromotetrachloroethane. The properties of 5-trimethylsilyltriazoloisoquinoline and its lithium derivative are reported; protodesilylation has been achieved with compounds (25)–(28).