CARB 70

OSW-1 is a saponin isolated from Galtonia candicans. It has been a very attractive synthetic target owing to its novel structure and highly potent anticancer activities. To study the structure-activity relationships of OSW-1 and to understand its detailed biological, toxicological and pharmacokinetic properties, it is necessary to have an efficient and reliable method to prepare OSW-1 in large quantities. In this context, we developed a new total synthesis for OSW-1. The aglycone was synthesized from commercially available 5-androsten-3â-ol-17-one in 8 steps with an overall yield of 15%, which involves minimum steps of column chromatography. A new route was also developed to prepare the disaccharide segment of OSW-1. Finally, the target molecule OSW-1 was achieved in 16 steps with a total yield of 6.6 % on multigram scales.