Ortho-quinone methide driven synthesis of kynurenic acid lactams

Abstract

Lactam formation of different KYNA amides and Mannich bases mediated by ortho-quinone methide has been investigated. The efficiency of the two routes of the cyclization process was revealed and the influence of diverse amide side chains was explored. In this regard compounds bearing a tertiary amine function in the amide side chain resulted in the formation of the lactam product, while the formation of dimer derivatives was observed in the case of other KYNA amides. Furthermore, derivatives bearing different substituents on the KYNA B ring were synthesized and their effects on the ring-closure reaction were investigated.