Novel radical synthesis of morphine fragments spiro[benzofuran-3(2H),4'-piperidine] and octahydro-1H-benzofuro[3,2-e]isoquinoline

A new strategy for the synthesis of oxide-containing fragments of morphine has been developed. Thus, the tricyclic (ANO) morphine fragment spiro[7-methoxybenzofuran-3(2H),4'-1'-methylpiperidine] (1) was obtained as the sole product via an intramolecular radical cyclization of 4-[(2'bromo-6'-methoxyphenoxy)methyl]-1,2,5,6,- tetrahydropyridine (9); while the tetracyclic (ACNO) fragment 9-methoxy-3-methyl-2,3,4,4a alpha,5,6,7,7a alpha-octahydro-1H- benzofuro[3,2-e]isoquinoline (3) and its 4-oxo analog 4 were synthesized in a similar fashion starting from 5,6,7,8-tetrahydroisoquinoline (10). Copyright (C) 1996 Elsevier Science Ltd.