An unusual 3,4-dihydroisoquinoline ring enlargement with the annulation of pyrazole

The treatment of substituted ethyl 1-(3′,4′-dihydro-3′,3′-dimethylisoquinolyl)-1- oximinoacetates with hydrazine hydrate leads to a 3,4-dihydroisoquinoline ring enlargement with the annulation of a pyrazole ring to form substituted 5,5-dimethyl-2,3,5,6-tetra-hydro-3-oxopyrazolo[3,4-b]benzo-3-azepines.