An expeditious synthesis of 3-(difluoromethoxy)- and 3-(trifluoromethoxy)-5,6,7,8-tetrahydro-1,6-naphthyridines

An expeditious and concise synthesis of 3-(difluoromethoxy)-5,6,7,8-tetrahydro-1,6-naphthyridine and 3-(trifluoromethoxy)-5,6,7,8-tetrahydro-1,6-naphthyridines is described. Starting from N-benzyl piperidone, the key intermediates leading to these two biologically desirable synthones were rapidly assembled by inverse electron demand Diels-Alder (IEDA) reaction utilizing microwave irradiation. The scope of the microwave methodology developed herein was extended to other ketones.