Enantioselective Palladium-Catalyzed Total Synthesis of Vitamin E by Employing a Domino Wacker–Heck Reaction
作者:Lutz F. Tietze、Florian Stecker、Julia Zinngrebe、Konrad M. Sommer
DOI:10.1002/chem.200600849
日期:2006.11.24
enantioselective total synthesis of vitamin E in which a novel palladium-catalyzed domino reaction was employed as the key step is described. This reaction allows the formation of the chiral chroman framework and the concurrent introduction of part of the side chain of vitamin E. The sequence comprises an enantioselective Wacker cyclization and a subsequent Heck reaction. Accordingly, reaction of alkenylphenol
描述了维生素E的对映选择性全合成,其中新的钯催化的多米诺骨牌反应被用作关键步骤。该反应允许形成手性苯并二氢吡喃骨架并同时引入维生素E侧链的一部分。该序列包括对映选择性Wacker环化和随后的Heck反应。因此,在催化量的Pd(OTFA)(2)(TFA =三氟乙酸酯),对映纯配体(S,S)-Bn-BOXAX(8 b; Bn)存在下,烯基苯酚12与甲基乙烯基酮(13)反应=苄基,BOXAX = 2,2′-双(恶唑基)-1,1′-联萘基和对苯醌(9)作为氧化剂以97%ee的对映选择性以84%收率得到手性苯并二氢吡喃10。然后,色醛10通过与(3R)-3的醛醇缩合反应转变为24,7-二甲基辛醛(11)。随后添加1,2-甲基锂,消除水和氢化产生维生素E.