A stereoselective synthesis of nonracemic (+)-desoxoprosophylline by a tandem Wittig [2+3]-cycloaddition reaction

L-Ascorbic acid serves as chiral starting material for the synthesis of (+) -desoxoprosophylline. The synthetic pathway includes the formation of an O- protected 5-azido-2,3-dideoxysugar which is subjected to a tandem Wittig [2 +3]- cycloaddition reaction, leading to the heterocyclic core unit of (+)-p rosophylline. Stereoselective hydrogenation and chain elongation yields the desired alkaloid.