Experiments on the total synthesis of Lysolipin I. Part III. Preparation and transformations of substituted 1,2,3,4-Tetrahydrodibenzofuran-1-ones
作者:Rudolf O. Duthaler、Veronica Scherrer
DOI:10.1002/hlca.19840670714
日期:1984.11.7
1,2,3,4-Tetrahydrodibenzofuran-1-ones were obtained by Michael addition of 1,3-cyclohexadione (2) to o-benzoquinone (3) and to p-benzoquinones 8 and 11 (Scheme 2). In addition to the expected 7,8-disubstituted adduct 14, the ZnCl2-catalyzed reaction of dione 2 with methoxy-p-benzoquinone (11) afforded a small amount of the 6,8-disubstituted regio-isomer 13 (Scheme 2). The projected cleavage of these
通过将1,3-环己二酮(2)迈克尔加成至邻苯醌(3)和对苯醌8和11(方案2),获得1,2,3,4-四氢二苯并呋喃-1-酮。除了预期的7,8-二取代的加合物14之外,ZnCl 2催化的二酮2与甲氧基-对-苯醌(11)的反应提供了少量的6,8-二取代的区域异构体13(方案2))。这些二苯并呋喃酮向3-甲氧基-2-苯基-2-环己烯酮22的预期裂解可以通过用NaOH处理然后进行甲基化来实现(方案3)。尝试将此类二苯并呋喃酮进行缩醛化反应会导致克莱森型裂解,从而产生16的苯并呋喃基丁酸酯。其他转化包括酮的还原,C(4a)= C(9b)键的还原,以及Li-乙氧基乙炔化物的烷基化(方案3)。8-羟基-7-甲氧基二苯并呋喃衍生物的氧化导致邻醌,而不是所需的环裂解成对醌(方案4)。