Polyhydroxylated indolizidine alkaloids - an efficient synthesis os 1-deoxy-8, 8a-epi-castanospermine

A new and efficient enantioselective total synthesis of the title deoxycastanospermine derivative has been developed, based on amino acid and b-ketophosphonate chemistry, as well as employment of internal asymmetric induction for the creation of the new chiral centers proved successful. With proper choice of reaction conditions, the approach can also be applied in selective preparation of several isomers of deoxycastanospermine. The length (9 steps) and overall yield of the title compound trihydroxyindolidine 1, 7.3%, compares well with the literature syntheses of similar compounds.