1-Hydroxy-3,5-dimethyl-2,4-benzodioates (4-hydroxyisophthalates) were prepared by [3+3] cyclocondensation of 1,3-bis(silyloxy)-1,3-butadienes with 3-ethoxycarbonyl-4-trimethylsilyloxy-3-penten-2-one which is synthesized from (symmetrical) ethyl 2-acetylacetoacetate. The [3+3] cyclization of 1,3-bis(silyloxy)-1,3-butadienes with 3-alkoxy-2-alkoxycarbonyl-2-en-1-ones, readily available by reaction of β-ketoesters with trialkyl orthoformiates, provide a convenient and regioselective approach to a great variety of 3-substituted 1-hydroxy-2,4-benzodioates that are not readily available by other methods.
1-羟基-3,5-二甲基-2,4-苯二酸酯(
4-羟基异
苯甲酸酯)是通过1,3-二(
硅氧基)-
1,3-丁二烯与3-乙氧基carbonyl-4-三甲基
硅氧基-
3-戊烯-2-酮的[3+3]环缩合反应制备的,该3-乙氧基carbonyl-4-三甲基
硅氧基-
3-戊烯-2-酮是从(对称)乙基2-
乙酰乙酸乙酯合成的。1,3-二(
硅氧基)-
1,3-丁二烯与3-烷氧基-2-烷氧基carbonyl-2-烯-1-酮的[3+3]环化反应,后者通过β-
酮酯与三烷基
甲酸醛的反应容易获得,提供了一种方便且区域选择性的途径,以合成多种不易通过其他方法获得的3-取代1-羟基-2,4-苯二酸酯。