Photoinduced Vinylogous Dearomatization

Abstract

The first vinylogous dearomatization is reported. Under a photoinduced platform, various benzothiophenes functionalized by ketones at the 3-position could react with 3-methylenechroman-4-ones efficiently, leading to a variety of valuable products that contain the pharmaceutically significant chromones and 2,3-dihydrobenzo­[b]­thiophenes concurrently. The transformations were revealed to experience hydrogen-atom transfer, dearomatization, olefin migration, and radical cross coupling.

Recent Developments on Photochemical Synthesis of 1,n‐Dicarbonyls

“…Jiang et al recently reported first vinylogous dearomatization of ketone functionalized benzothiophenes with chromanone derivatives for the synthesis of 1,6-dicarbonyl compounds (Scheme 58). [103] As per the plausible reaction mechanism, upon irradiation of blue LED benzothiophene 81 generates its triplet state 81* via intersystem crossing (ISC), which then undergoes hydrogen atom transfer (HAT) with chromanone derivatives 82 and produces ketyl radical A and radical B. Subsequently, A undergoes dearomatization to generate radical D and B produces radical C via olefin isomerization.…”