Rearrangement of spiro [2H-1-benzopyran-2,2 '-[2H] indoles] to pyrrolo[1,2-a]indole derivatives
Heating of 1'-(N-substituted carbamoyl)methylspiro[2H-1-benzopyran-2,2'-[2H]indoles] with potassium hydroxide in ethanol yields diastereomeric 5a,13-methano-6H-1,3-benzoxazepino[3,2-a]indole-12-carboxamides. Reduction of the latter with sodium borohydride affords 1,2,3,9a-tetrahydro-2-hydroxyaryl-9H-pyrrolo[1,2-a]indole-3-carboxamides .