Total synthesis of (−)-codonopsinol and (+)-2-epi codonopsinol via acid catalyzed amido cyclisation

A short and stereoselective synthesis of (−)-codonopsinol 5 and its C-2 epimer 6 were accomplished from commercially available starting material d-1,5-gluconolactone, using acid mediated amido cyclisation as the key step. The inhibitory activitiy of these compounds against glucosidase and galactosidase has been studied.