RESUMEN
An efficient synthetic approach to the core structure of the manzamine alkaloids is reported, particularly in relation to incorporating a one-carbon unit in ring B from which the aldehyde in ircinal A or the beta-carboline unit in manzamine A could potentially be generated. The key steps involve a Johnson-Claisen rearrangement, enolate alkylation, dithiane alkylation and a stereoselective intramolecular dipolar cycloaddition of an azomethine ylide, which provided the desired tricyclic ABC core structure.
Asunto(s)
Carbazoles/síntesis química , Carbazoles/química , Cristalografía por Rayos X , Modelos Moleculares , Estructura MolecularRESUMEN
Quaternary stereocenters: Chiral α-magnesiated nitriles can be formed by deprotonation and are configurationally stable at low temperature, even for acyclic examples. These can be trapped with electrophiles to give enantiomerically enriched quaternary substituted products (see scheme; TMP = 2,2,6,6-tetramethylpiperidine).