Transition‐Metal Free Catalytic Synthesis of Trifluoromethyl Indolines by [4+1] Cycloaddition of Trifluoromethyl Benzoxazinones with Sulfur Ylides
作者:Koki Kawai、Hiroto Uno、Daichi Fujimoto、Norio Shibata
DOI:10.1002/hlca.202000217
日期:2021.1
Stereoselective catalytic synthesis of 3‐trifluoromethyl indolines through the [4+1] cycloaddition of benzoxazinones and sulfur ylides in a transition‐metal‐free manner was developed. In the presence of a catalytic amount of sodium hydride, aza‐ortho‐quinone methide intermediates were formed from trifluoromethyl benzoxazinones through decarboxylation after the first nucleophilic attack of sulfur ylides
通过无过渡金属的方式,通过[4 + 1]苯并恶嗪酮和硫酰化物的环加成反应,开发了3-三氟甲基吲哚的立体选择性催化合成方法。在催化量的氢化钠,氮杂邻苯二甲酸存在下甲基苯醌中间体是由三氟甲基苯并嗪酮在脱硫后通过脱羧作用形成的,首先发生了硫酰化物的亲核攻击,随后又发生了对亲硫基团的第二次亲核攻击,从而导致了[4 + 1]环加成反应。催化转化的关键是硫酰化物对底物的双重攻击。这种独特的不含过渡金属的方案适用于非氟化乙烯基,乙炔基或甲基取代的二氢吲哚的合成。还描述了化学计量条件下3-三氟甲基吲哚的合成。