拜尔-维利格氧化是一种有价值的反应,可以将酮转化为酯或内酯。在这里,我们提出了一种新颖且有效的方法,利用 I 2作为环丁烯酮氧化重排的催化剂,从而合成呋喃-2(5 H )-酮。值得注意的是,该方法采用二甲亚砜 (DMSO) 作为更环保的氧化剂和氧源。在催化量的碘的作用下,反应顺利进行,以良好的产率产生内酯。与依赖过酸或过氧化氢的传统拜尔-维利格氧化反应相比,DMSO 的使用提供了更安全、更通用的替代方案。
Highlyenantioselective ring-opening/cycloaddition reactions of cyclobutenones were achieved by employing chiralN,N′-dioxide/metalcomplexes as the catalysts. The Diels–Alder type cycloaddition with (E)-alkenyloxindoles yielded spirocyclohexaneoxindoles with excellent results. Meanwhile, a hetero-Diels–Alder process occurred with (E)-dioxopyrrolidines to afford spiropyrrolidinone-dihydropyranone derivatives
two‐carbon (C2) cyclization buildingblock. The present protocol successfully inhibits the competitive cycloaddition with the C≡N bond of acetonitrile, but enables the in situ formation of an unsaturated carbon–carbonbond and the subsequent cycloaddition as a C2 unit. This chemistry features simple reaction conditions, high chemoselectivities, wide substrate scope, and offers a new and practical approach
Enantioselective Synthesis of 3‐Substituted Cyclobutenes by Catalytic Conjugate Addition/Trapping Strategies
作者:Changxu Zhong、Yingchao Huang、Haocheng Zhang、Qiang Zhou、Yu Liu、Ping Lu
DOI:10.1002/anie.201913825
日期:2020.2.10
A copper-catalyzed tandem process to generate chiral cyclobutene derivatives has been developed. It is based on an enantioselective conjugate addition or reduction of a cyclobutenone and sequential trapping with a chlorophosphate in a one-pot process. These phosphates are stable under mildly acidic conditions and serve as good electrophiles in Negishi coupling reactions.
A highly diastereo- and enantioselectivering-opening/cycloaddition reaction of cyclobutenones with 2-hydroxyacetophenones or salicylaldehyde was achieved by employing a chiral N,N′-dioxide-scandium(III) complex as the catalyst. It provided various 3-phenylvinyl-4-hydroxy-dihydrocoumarins in good yields (up to 92%), high enantioselectivities (up to 93% ee), and excellent diastereoselectivities (>19:1
Rh(<scp>iii</scp>)-Catalyzed acylation of heteroarenes with cyclobutenones <i>via</i> C–H/C–C bond activation
作者:Yixin Cui、Dachang Bai、Bingxian Liu、Junbiao Chang、Xingwei Li
DOI:10.1039/d0cc05965j
日期:——
Rhodium(iii)-catalyzedC-H acylation of heteroarenes has been realized using cyclobutenones as an acylating reagent. This coupling proceeded via integration of C-H activation of heteroarenes and C-C cleavage of cyclobutenones. The reaction features excellent regio/chemoselectivity leading to versatile chalcones with exclusive E-selectivity.