OXIDATIVE RADICAL CYCLIZATION OF (OMEGA-IODOALKYL)INDOLES AND PYRROLES - SYNTHESIS OF (-)-MONOMORINE AND 3 DIASTEREOMERS

Addition of excess hydrogen peroxide (10 equiv) to a sonicated solutio n of FeSO4:7H(2)O (1 equiv) in Dh ISO containing the N-(omega-iodoalky l)indoles 4, 5, 11, and 13 effected oxidative radical cyclization to 6 , 7, 14, and 15, respectively. The (omega-iodoalkyl)pyrroles 21, 22, 2 7, 38, and 49 underwent analogous cyclization reactions to 23, 24, 28, 39, and 50, respectively. The regiochemistry of these radical cycliza tion reactions was correctly predicted by FMO calculations in all case s but one. For compound 38, FMO calculations indicated that radical at tack should take place at both C-3 and C-5. Only the product of cycliz ation at C-5, i.e., 39, was observed. The enantiomerically pure bicycl ic ketone 42, prepared by the above technique from the iodide 53, was converted into 55 which, on catalytic reduction (H-2/Rh-A1(2)O(3)), ga ve a mixture of (-)-monomorine (40) and three of its diastereomers 56- 58 (see, however, Note Added in Proof).