Synthesis of β-carbolines using microwave-assisted aza-Wittig methodology in ionic liquids
作者:Pilar M. Fresneda、Jose Antonio Blázquez
DOI:10.1016/j.tetlet.2012.03.049
日期:2012.5
The improved preparation of 1-substituted-β-carbolines is reported using microwave-assisted aza-Wittig/electrocyclic ring-closure reaction with ionic liquids as solvent. In all cases an unprecedented N-methoxymethyl group (MOM) deprotection is observed.
A palladium-catalyzed imidoylative cyclization of ethyl-3-(1H-indol-3-yl)-2-isocyanopropanoates, derived from readily available tryptophan, to afford β-carboline derivatives has been developed. The reaction proceeds smoothly under mild conditions through sequential isocyanide insertion, intramolecular C–H imidoylation, and aerobic dehydrogenative aromatization with a decent substrate scope. This method