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Paper | Regular issue | Vol 94, No. 9, 2017, pp.1678-1692
Published online, 13th July, 2017
DOI: 10.3987/COM-17-13743
Synthesis of 2,3-Dihydrobenzo[b]thiophen-3-amine 1,1-Dioxide Derivatives via LDA-Mediated Cyclization of o-(Alkylsulfonyl)benzyl Azides with Denitrogenation

Kazuhiro Kobayashi,* Yuuki Chikazawa, and Takashi Nogi

*Applied Chemistry Field, Chemistry and Biotechnology Course, Department of Engineering, Graduate School of Sustainability Science, Tottori University, 4-101 Koyama-minami, Tottori 680-8552, Japan

Abstract

A new and efficient method for the synthesis of 2,3-dihydrobenzo[b]thiophen-3-amine 1,1-dioxide derivatives has been developed. Thus, treatment of o-(alkylsulfonyl)benzyl azides, which are readily obtainable from commercially available starting materials by easily operational sequences, with lithium diisopropylamide (LDA) in THF at –78 ˚C gives, after aqueous workup, 2,3-dihydrobenzo[b]thiophen-3-amine 1,1-dioxides. These products can be isolated in moderate to fair yields after N-protection with acylating agents.