SYNTHESIS OF VINCA ALKALOIDS AND RELATED COMPOUNDS XLII TRANSFORMATION OF VINCAMONE INTO VINCAMINES VIA DIAZOMETHANE ASSISTED HOMOLOGIZATION. APPLICATION OF(1)H-NOE MEASUREMENTS FOR THE CONFIGURATIONAL ASSIGMENT OF THE SPIRO-OXIRANE RING

Article abstract of DOI:10.1016/S0040-4020(01)86164-0

The α-oxo-acids 4 and 5 derived from vincamone (1) were transformed into vincamines 2,9,10, respectively by methylene insertion with diazomethane.Homologization of 3 and 6 dioxo compounds led to oxirane derivatives 8,16,11,13, 18, respectively.Configuration of the oxiranes was determined by (1)H-NOE measurements.