Enantioselective Synthesis of Chromans for the Preparation of Enantiopure Vitamin E and Analogues
作者:Lutz F. Tietze、Jochen Görlitzer
DOI:10.1055/s-1997-1278
日期:1997.8
Coupling of the different protected (hydroxymethyl)enynes 11a-e and 12a-c with the iodoarene 7 in the presence of catalytic amounts of Pd(PPh3)4 afforded the arylenynes 5a-e and 6a-c which were transformed into the monoprotected chiral trihydroxy compounds 13a-d and 14a,b by Sharpless bishydroxylation with >95% ee for 13a-d, 91% ee for 14b and 64% ee for 14a. A 5-step transformation of 13a led to the desired chroman derivative 3a which was cleaved to give the aldehyde 2 a known precursor for the enantioselective synthesis of vitamin E.
不同保护形式的(羟甲基)烯炔 11a-e 和 12a-c 在催化量的 Pd(PPh3)4 存在下与碘芳烃 7 发生偶联反应,得到了芳烯炔 5a-e 和 6a-c,这些化合物通过 Sharpless 双羟基化转化为单保护的手性三羟基化合物 13a-d 和 14a,b,其中 13a-d 的较高对映体过量达到 >95%,14b 的对映体过量为 91%,14a 的对映体过量为 64%。对 13a 进行 5 步转化,得到了所需的 chroman 衍生物 3a,该化合物经过裂解生成醛 2,这是一种已知的维生素 E 选择性合成的前体。