Intermolecular [2 + 2] Photocycloaddition of α,β-Unsaturated Sulfones: Catalyst-Free Reaction and Catalytic Variants
作者:Noah Jeremias、Lisa-Marie Mohr、Thorsten Bach
DOI:10.1021/acs.orglett.1c01794
日期:2021.8.6
2-Aryl-1-sulfonyl-substituted cyclobutanes were prepared in an intermolecular [2 + 2] photocycloaddition from various α,β-unsaturated sulfones and olefins upon irradiation at λ = 300 nm (26 examples, 60–99% yield). Lewis acids catalyzed the [2 + 2] photocycloaddition of 2-benzimidazolyl styryl sulfones. At short wavelengths, the latter substrates underwent C–S bond cleavage but AlBr3 (5 mol %) allowed
2-Aryl-1-磺酰基取代的环丁烷是在 λ = 300 nm 照射下,通过分子间 [2 + 2] 光环加成反应制备的(26 个例子,产率 60-99%)。路易斯酸催化 2-苯并咪唑基苯乙烯基砜的 [2 + 2] 光环加成。在短波长下,后一种底物经历 C-S 键断裂,但 AlBr 3 (5 mol %) 允许在较长波长下与 2,3-二甲基-2-丁烯发生分子间反应。手性金属路易斯酸(2 mol%)促进了对映选择性反应(高达 77% ee)。