Enantioselective Robinson Annulation: Synthesis of (+)-O-Methyljoubertiamine

Article abstract of DOI:10.1021/jo00277a017

The α-formyl ester derived from 2-(1-naphthyl)-3-borneol, as the potassium salt in moist dimethoxymethane, adds to methyl vinyl ketone to give two adducts in a ratio of 95:5.The relative configuration of the major diastereomer has been confirmed by X-ray crystallography.This diastereomer is readily carried on to (+)-O-methyljoubertiamine.The addition of such naphthylbornyl esters to Michael acceptors should constitute a general laboratory-scale procedure for the enantioselective construction of enantiomerically pure quaternary stereogenic centers.