Department of Chemistry, Indian Institute of Technology Kharagpur , Kharagpur 721302, India.
Org Lett. 2017 Feb 3;19(3):464-467. doi: 10.1021/acs.orglett.6b03612. Epub 2017 Jan 12.
The synthesis of sensitive β-alkyl 3-vinylindoles having diverse functional groups with good selectivity remains a challenging task. Keeping the synthetic utility of 3-alkenylindoles in mind, we explored a unique approach to synthesize them from unprotected indoles in a domino fashion. A transition-metal-free C3-alkenylation of indole is reported by using sequential Brønsted acid/base catalysis. Several β-substituted 3-alkenylindoles and conjugated 1,3-dienes are synthesized by direct coupling of indole and readily available aliphatic aldehydes. Excellent scalability and recycling of benzenesulfinic acid for successive alkenylation reactions up to five times make this method economically viable.
具有各种官能团的敏感β-烷基 3-乙烯基吲哚的合成具有良好的选择性，这仍然是一项具有挑战性的任务。考虑到 3-烯基吲哚的合成实用性，我们探索了一种独特的方法，从无保护的吲哚以级联方式合成它们。本文报道了一种无过渡金属的 C3-烯基化吲哚的方法，该方法通过顺序 Brønsted 酸/碱催化实现。通过吲哚与易得的脂肪醛的直接偶联，合成了几种β-取代的 3-烯基吲哚和共轭的 1,3-二烯。苯亚磺酸的出色可扩展性和循环使用可进行多达五次的连续烯基化反应，使得该方法具有经济可行性。
