Studies on Pyrimidine-Annelated Heterocycles:  Synthesis of Pyrrolo[3,2-<i>d</i>]pyrimidines by Amine Oxide Rearrangement

Abstract

A number of pyrrolo[3,2- d ]pyrimidine derivatives ( 5a − f ) were synthesized in 90−95% yields from the corresponding 5-[ N -[4-(aryloxy)but-2-ynyl]- N -ethylamino]-1,3-dimethyluracils 4a − f by simple treatment with 1 equiv of m -chloroperoxybenzoic acid in dichloromethane at 0−5 °C for 12−15 h. The resulting benzoates ( 5a − f ) were easily converted to methoxy derivatives 11a − f in 92−94% yields when refluxed in methanol for 20−22 h.