Farah Abdikani Omar, Garcia Jorge, Borg Claire, Beng Timothy K
Department of Chemistry, Central Washington University Ellensburg WA 98926 USA
RSC Adv. 2023 Jan 23;13(5):3181-3185. doi: 10.1039/d2ra07916j. eCollection 2023 Jan 18.
Functionalized 1,3-dienes are ubiquitous structural motifs in biologically pertinent molecules. They are frequently employed as precursors for a broad range of chemical transformations, including Diels-Alder reactions. The stereoselective construction of highly decorated 1,3-dienes therefore represents an important research objective. Medicinal chemists are becoming increasingly interested in synthetic methodologies that not only achieve expedient construction and peripheral editing of heterocycles, but also seek to modify their core framework in order to achieve skeletal remodeling. In a succinct manifestation of this 'scaffold hopping' concept, we herein describe a cascade reaction, which converts thiomorpholinone-tethered alkenoic acids to 1,1-disubstituted amino-1,3-dienes. This domino process involves esterification of the acid, base-assisted ring-opening, and concomitant 1,2-migration of the α-amino alkenyl group. Several control experiments have revealed that the alkenyl substituent is necessary for deconstruction to occur. Inherently more activated -aryl-substituted thiomorpholinone acids react significantly faster than their less activated -alkyl congeners.
官能化的1,3 - 二烯是生物相关分子中普遍存在的结构基序。它们经常被用作广泛化学转化的前体,包括狄尔斯 - 阿尔德反应。因此,高度修饰的1,3 - 二烯的立体选择性构建是一个重要的研究目标。药物化学家对合成方法越来越感兴趣,这些方法不仅能实现杂环的便捷构建和外围修饰,还试图修改其核心框架以实现骨架重塑。作为这种“骨架跃迁”概念的简洁体现,我们在此描述一种串联反应,该反应将硫代吗啉酮连接的链烯酸转化为1,1 - 二取代氨基 - 1,3 - 二烯。这个多米诺过程涉及酸的酯化、碱辅助的开环以及α - 氨基烯基的伴随1,2 - 迁移。几个对照实验表明,烯基取代基是解构发生所必需的。本质上更具活性的芳基取代硫代吗啉酮酸的反应速度明显快于活性较低的烷基同系物。