SPECTRAL PROPERTIES OF RING-C-OXYGENATED 4-AZAFLUORENES AND 4-AZAFLUORENONES. THE STRUCTURES OF NATURAL ONYCHINE DERIVA TIVES

Abstract

4-Azafluorenes bcaring a methoxy group at C-5, -6, -7 or -8 and a methyl at Col or -3 were synthesized by thermolysis of O-crotyloximes of appropriately substitutcd indan-I-ones. The corrcsponding azalluorenones were prepared, and the methoxy-I-methyl-4-azafluoren-9-one isomers were 0- demethylated. The proton nmr, uv-visible and mass spcctra of these compounds support the structures assigned to the more complex azafluorenone alkaloids kinabaline, darienine and macondine, and provide addiLional guidelines for the structure elucidation of other natural products bclonging to this class.