Synthesis and Identification of a Novel 6,5,6-Tricyclic Lactam

We recently described a novel series of tyrosine-based PPARgamma agonist exemplified by GI262570.(1) A series of oxazole targets included in this work were synthesized via cyclodehydration of substituted aldehyde amides. During the course of this work, an unexpected tricyclic lactam was isolated as the major product from one of the cyclodehydration reactions. In this report we describe the synthesis and structural characterization of the unexpected tricyclic compound (5). A proposed mechanism for the formation of tricyclic lactam (5) is also presented.