Formal [3+3] cyclocondensations of 1,3-bis(silyloxy)-1,3-butadienes with 1-chloro-1,1-difluoro-4,4-dimethoxybut-3-en-2-one and 1,1-difluoro-4,4-dimethoxybut-3-en-2-one. Regioselective synthesis of fluorinated salicylates and pyran-4-ones
作者:Sebastian Reimann、Alina Bunescu、Robert Litschko、Silke Erfle、Lutz Domke、Franziska Bendrath、Zharylkasyn A. Abilov、Anke Spannenberg、Alexander Villinger、Peter Langer
DOI:10.1016/j.jfluchem.2012.03.019
日期:2012.7
salicylates, respectively. The Me3SiOTf-mediated [3+3] cyclocondensation of the same building blocks provided CF2Cl- and CF2H-substituted pyran-4-ones and CF2Cl-substituted cyclohexenones. The formation of CF2H-substituted cyclohexenones was not observed. Besides the type of Lewis acid, the product distribution is also influenced by the substitution pattern of the 1,3-bis(silyloxy)-1,3-butadiene: The Me3SiOTf
TiCl 4介导的1,3-双(甲硅烷氧基)-1,3-丁二烯与1-氯-1,1-二氟-4,4-二甲氧基丁-3-烯-2-酮的[3 + 3]环缩合或1,1-二氟-4,4-二甲氧基丁-3-烯-2-酮分别提供CF 2 Cl-和CF 2 H-取代的水杨酸酯。Me 3 SiOTf介导的相同结构单元的[3 + 3]环缩合提供了CF 2 Cl-和CF 2 H取代的吡喃-4-酮和CF 2 Cl取代的环己烯酮。未观察到CF 2 H-取代的环己烯酮的形成。除路易斯酸的类型外,产物分布还受1,3-双(甲硅烷氧基)-1,3-丁二烯的取代模式的影响:Me 3SiOTf介导的C4-未取代的二烯环化导致形成CF 2 Cl-取代的吡喃-4-酮,而C4-取代的二烯的环化提供CF 2 Cl-取代的环己烯酮。TiCl 4介导的用1,1-二氟-4,4-二甲氧基丁-3-en-2-one对C4取代的二烯的环化失败。因此,通过用氢化三丁基锡转化各个CF