Synthesis of Dihydrooxazines from a Modified Bischler-Aapieralski Reaction

Abstract

As part of our studies towards the synthesis of 4-hydroxy-1, 2, 3, 4-tetrahydroisoquinoline derivatives^1–2 we have investigated the dehydration of amidoketals(1). Dehydration of β-amidoketones leads to the formation of oxazoles³, but a modified Bischler-Napieralski reaction of the ethylene ketal (1a) to the 3, 4-dihydroisoquinoline (2a) has been reported⁴. This route to 4-oxo-