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'-methoxyphenoxyl)methyl]-1-methyl-1,2,5,6-tetrahydropyr idine (9); while the tetrayclic (ACNO) fragmet 9-methoxy-3-methyl-2,3,4,4aα,5,6,7,7aα-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).