Highly Diastereoselective Tandem Photoenolization−Hetero-Diels−Alder Cycloaddition Reactions of <i>o</i>-Tolualdehydes in the Solid State
作者:Jarugu Narasimha Moorthy、Prasenjit Mal、Nidhi Singhal、Parthasarathi Venkatakrishnan、Ravish Malik、Paloth Venugopalan
DOI:10.1021/jo048482a
日期:2004.11.1
the solid state efficiently for aldehydes whose (E)-photoenols (i) are more stable than their corresponding benzocyclobutenols and (ii) are not sterically congested. However, rapid cyclization to benzocyclobutenols is found to be the sole pathway for sterically encumbered (E)-enols derived from aldehydes 6−8. Given that the execution of heteromolecular reactions in the solid state is a challenge, the
的(ê)-photoenols原位产生由光解ö -tolualdehydes 1 - 5在固体状态下与前体反应的醛如在杂狄尔斯-阿尔德环加成方式的亲二烯体,得到反式-3- arylisochromanols以优良产率和在高非对映选择性。对三种不同类别的合理设计的醛的反应性进行的研究表明,对于((E)-光烯醇(i)比其相应的苯并环丁烯醇更稳定,并且(ii)在空间上不拥挤。然而,快速环化benzocyclobutenols被发现对于空间位阻(唯一途径ë)-enols由醛衍生的6 - 8。鉴于在固态heteromolecular反应的执行是一个挑战,用简单的结晶获得的结果Ò-甲苯甲醛是引人注目的,并且涉及在双亲亲晶体中原位生成二烯醇以高度非对映选择性的方式实现异Diels-Alder反应的策略是前所未有的。在当代合成有机化学中对串联/多米诺反应的极大兴趣的背景下,邻甲苯甲醛所观察到的结果证明了固态下串联反应的成功实施。