Novel synthesis of chromene and benzofuran derivatives via the Nenitzescu reaction

The condensation of 3-oxocaprolactam piperidine enamine with 2,6-dibromoquinone and quinone gave 6,8-dibromo-7-hydroxy- and 7-hydroxy-10a-piperidine-2,3,4,5,5a-hexahydro-1H-benzofuro[2,3-c]azepine-1-one adducts, the acid treatment of which afforded novel 9-hydroxy-1,2,3,4-tetrahydro-5H-chromene[3,4-b]pyridine-5-one derivatives.