Development of a Practical Synthesis of a Functionalized Pyrrolo[2,1-f][1,2,4]triazine Nucleus

Functionalized pyrrolotriazine 1b is a key heterocyclic building block in the synthesis of BMS-690514, a potent anticancer agent. Described herein are our development activities that led to the efficient preparation of 1b on a large scale. The key transformations include a selective C-alkylation of an oxalacetate salt with a hydrazonyl bromide to form a 2-hydrazonoethyl-3-oxosuccinate, followed by cyclodehydration to an aminopyrrole. Subsequent deprotection and condensation with formamidine afforded the pyrrolotriazine scaffold. Further elaboration of this core provided the desired pyrrolotriazinyl amine.