Diastereoselective synthesis of new polyhydroxylated indolizidines from (l)-glutamic acid

A diastereoselective synthesis of two new swainsonineʹs analogues and with the piperidine ring fused to a phenyl nucleus at C6-C7, namely (1R, 2S, 10R, 10aR)-(+)-1,2,10-trihydroxy-1,2,3,5,10,10a-hexahydrobenzo[f] indolizine () and (1S, 2R, 10R, 10aR)-(+)-1,2,10-trihydroxy-1, 2, 3, 5, 10, 10a-hexahydrobenzo[f] indolizine (), is described. Throughout this work, the effectiveness of the tricyclic indolizidine dione , readily available in three steps from the cheap l-glutamic acid, as an attractive platform for chemo- and stereodivergent transformations is illustrated. The key steps involved totally diastereoselective ketone reduction of compound and catalytic cis-dihydroxylation of the unsaturated amide . The synthetic strategy also allowed for the diastereoselective synthesis of benzoanalogues of the 1,8a-di-epi-lentiginosine ((1R, 2S, 10aR)-(+)-1,2-dihydroxy-1, 2, 3, 5, 10, 10a-hexahydrobenzo[f]indolizine) and 2,8a-di-epi-lentiginosine ((1S, 2R, 10aR)-(+)-1,2-dihydroxy-1,2,3,5,10,10a-hexahydrobenzo[f]indolizine).