Dearomative ring expansion of thiophenes by bicyclobutane insertion

作者：Huamin Wang, Huiling Shao, Ankita Das, Subhabrata Dutta, Hok Tsun Chan, Constantin G. Daniliuc, K. N. Houk, Frank Glorius · 发表于：Science · 年份：2023 · DOI：10.1126/science.adh9737 · 被引用次数：223 · 研究领域：Radical Photochemical Reactions、Catalytic C–H Functionalization Methods、Sulfur-Based Synthesis Techniques

Skeletal ring enlargement is gaining renewed interest in synthetic chemistry and has recently focused on insertion of one or two atoms. Strategies for heterocyclic expansion through small-ring insertion remain elusive, although they would lead to the efficient formation of bicyclic products. Here, we report a photoinduced dearomative ring enlargement of thiophenes by insertion of bicyclo[1.1.0]butanes to produce eight-membered bicyclic rings under mild conditions. The synthetic value, broad functional-group compatibility, and excellent chemo- and regioselectivity were demonstrated by scope evaluation and product derivatization. Experimental and computational studies point toward a photoredox-induced radical pathway.