First Friedel−Crafts Diacylation of a Phenanthrene as the Basis for an Efficient Synthesis of Nonracemic [7]Helicenes
作者:Kamil Paruch、Thomas J. Katz、Christopher Incarvito、Kin-Chung Lam、Brian Rhatigan、Arnold L. Rheingold
DOI:10.1021/jo001055m
日期:2000.11.1
first examples of Friedel-Crafts reactions used to prepare 3,6-diacylphenanthrenes. 9,10-Dimethoxyphenanthrene gives its 3,6-diacetyl derivative in good yield and in large amounts. The ketone's triisopropylsilyl enol ether when combined with 1, 4-benzoquinone forms a [7]helicenebisquinone. This bisquinone's reduction product, a bishydroquinone, when combined with methanolic HCl gives the [7]helicene
报道了用于制备3,6-二乙烯基菲的弗瑞德-克来福特反应的第一个实例。9,10-二甲氧基菲以高收率和大量得到其3,6-二乙酰基衍生物。酮的三异丙基甲硅烷基烯醇醚与1,4-苯醌组合形成[7] hel烯双醌。该双醌的还原产物双氢醌与甲醇HCl结合后可生成[7] hel烯,其外围侧链均为甲氧基,但内部羟基仍然保留。非对映异构体(1S)-(-)-樟脑酸酯可通过结晶分离。通过X射线衍射分析其结构,表明当螺旋烯具有(P)构型时,樟脑酸酯的内酯官能团指向远离环系统,而当螺旋烯具有(M)构型时,指向内酯官能团。这是因为,正如预期的那样,樟脑的O = CCO二面角在前者中接近0度,在后者中接近180度。制备3,6-二乙酰基菲和[7]]烯双醌的其他衍生物,并分析后者之一的晶体结构。