Asymmetric Synthesis of Usseful Natural Products by Means of Organosilicon Compounds

我们已经报道了光学活性的3-(1，4-戊二烯基)苯甲基二硅氧烷在钯(叔烷基异氰基)络合物催化下的高非对映选择性分子内双硅烷基化反应，高产率地合成了3(R)，4(R)，5(R)-三取代的2-硅四氢呋喃。指出了分子内双硅烷化反应中高度可控的非对映界面选择。合成的(R，R，R)-2-四氢呋喃用于全合成(-)-燕麦内酯的合成方法如下。Rh催化5元(R，R，R)-2-硅烷四氢呋喃上的乙烯基的区域选择性氢化反应，然后氧化得到相应的伯醇。接下来，两个硅-碳键被氧化裂解，在保留立体化学的情况下转化为相应的醇。经过适当的保护和去保护，伯醇在酸性条件下被氧化成相应的双内酯。最后，内酯环上的选择性亚甲基化得到(-)-文奈酯内酯。本研究中的(-)-艾维奈酯的全合成为基于硅碳键的立体选择性构筑提供了一条新的有效途径。硅碳键是羟基的合成等价物。

We have previouly described highly diastereoselective intramolecular bissilylation of optically active 3- (1,4-pentadienyl) phenylmethyl disilanylether catalyzed by palladium (tert-alkylisocyanide) complex, producing 3 (R), 4 (R), 5 (R) -trisubstituted 2-silatetrahydrofuran in high yield. The highly controlled diastereoface selection in the intramolecular bis-silylation is remarked. The (R,R,R) -2-silatetrahydrofuran thus prepared was synthetically elaborated for total synthesis of (-) -avenaciolide as follows. Rhodium catalyzed regioselective hydroboration of the vinyl group on the five membered (R,R,R) -2-silatetrahydrofuran was followed by oxidation to give the corresponding primary alchohol. Next, the two silicon-carbon bonds were oxidatively cleaved to convert to the corresponding alchohols with retention of stereochemistry. After appropriate protection and then deprotection, the primary alcohols were oxidized to give the corresponding bis-lactone under acidic condition. Finally, selective methylenation on the lactone ring furnished (-) -Avenaciolide. The total synthesis of (-) -Avenaciolide in this research presented a new and efficient approach on the basis of stereoselective construction of silicon-carbon bonds, which are synthetic equivalents to hydroxy groups.