The Synthsis Of Solasodine And An Analog Of OSW-1

Resource Chemistry is one of the most important research field in our group. The one of the most important tasks of our group is exploring the reaction of a veriety of resource compounds and their application in the synthesis of medicine, agricultural agents and natural product with potential bioactivity in order to realize the rational and high effient utilization of the abundant resource compounds in our country and the elimination of industrous waste. My dissertation is concerted on the synthesis of two products: Solasodine and an analog of OSW-1 by utilizing the intact skeleton of diosgenin.For the synthesis of Solasodine, diosgenin was firstly protected at C-3, C-5(6), followed the oxidation by Oxone at C-16 to afford the C-3, C-5(6) protected 16-hydroxyldiosgenin. The latter reacted with HBr/HOAc to directly produced 26-bromo-16, 22-diketone via a new brominating dekatalization reaction found in our group. 26-bromo-16, 22-diketone suffered the zinc powder selectively reducted dibromine at C-5,6 , replaced bromine at C-26 by NaN₃, selectively reduced ketone at C-16 by NaBH4 and at C-26 by NaI and TMSCl, hydrolyzed at C-3 by K2CO3/CH3OH a series of reaction to result in the formation of Solasodine in nine steps in 21.3% overall yield.During the synthesis of the 17-brom-OSW-1 sapogenin, disogenin was converted to 16, 22-diketone in four steps as same as the methods of the syntheses of Solasodine. And then the 16, 22-diketone reacted with zinc powder to remove bromoine at C5(6) and C26. The 16-carbonyl the of 16, 22-diketone was converted to 16(17) double bond via a series of reaction including 16-thioacetal, thioketal-opening-acetylization and desulfurization with Raney nickel. Through the ethylene glycol ketal protection of 22-ketone and the protection of 3-hydroxy, 5,6-alkene at the same time, addition of 16,17-alkene function with NBS and H₂O, we will complete the synthesis of the protected 17-bromo-OSW-1 sapogenin. Unforturnately, we did not get the pure compound in the experiments so we did not identify its exact structure.