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。
Efficient Approach to 1,2-Diazepines via Formal Diazomethylene Insertion into the C–C bond of Cyclobutenones
摘要:
Efficient monocyclic 1,2-diazepine formation via a tandem electrocyclization reaction of cyclobutenones with lithiodiazoacetate is demonstrated. The reaction proceeds through an oxy anion-accelerated 4 pi-ring opening of cyclobutene followed by an 8 pi-ring closure of the resultant oxy anion-substituted diazo-diene under mild conditions to furnish a 1,2-diazepine via formal diazomethylene insertion into the C-C bond of cyclobutenone.
A regioselective synthesis of general applicability has been designed for the one‐pot preparation of 2,3‐disubstituted‐cyclobutenones from iodoalkynes through cyclobutenylation, Suzuki CC coupling, and ketone formation. This one‐pot methodology has been applied to the selective synthesis of an orally active cyclooxygenase II inhibitor. Furthermore, the obtained cyclobut‐2‐en‐1‐ones were used as synthons
Cu<sup>I</sup>-Catalyzed Asymmetric [3 + 2] Cycloaddition of Azomethine Ylides with Cyclobutenones
作者:Javier Corpas、Alberto Ponce、Javier Adrio、Juan C. Carretero
DOI:10.1021/acs.orglett.8b00936
日期:2018.6.1
The catalytic asymmetric 1,3-dipolar cycloaddition of cyclobutenones with azomethineylides provides straightforward access to densely substituted 3-azabicyclo[3.2.0]heptanes. In the presence of CuI/(R)-Fesulphos as the catalytic system, high levels of diastereoselectivity and enantioselectivity were achieved (up to 98% enantiomeric excess (ee)).
环丁烯酮与偶氮甲亚胺的催化不对称1,3-偶极环加成反应可直接获得致密取代的3-氮杂双环[3.2.0]庚烷。在Cu I /(R)-Fesulphos作为催化体系的存在下,实现了高水平的非对映选择性和对映选择性(对映体过量(ee)高达98%)。
Reaction of Oxocyclobutenyl Palladium(II) Complex with Terminal Alkynes or Organozincs Affording Differently 2,3-Disubstituted Cyclobutenones
The reaction of the oxocyclobutenyl palladium(II) complex 2 with terminal alkyne 3 in the presence of CuI or with organozincs yielded differently 2,3-disubstituted cyclobutenones 4 or 5 via the stoichiometric Sonogashira- or Negishi-type reactions, respectively. In addition, the possibility of the synthesis of cyclobutenones 4 from 1, CO, and 3 catalyzed by the Pd complex was also demonstrated.
and silylation of dichlorocyclobutenones, which furnish the boron-substituted and silicon-substituted polyfunctionalized cyclobutenones in high yields. The reactions proceed under mild reaction conditions, show broad substrate scope, and display high chemoselectivity. In addition, a series of transformations of the corresponding products has been realized.
In 1,1,1,3,3,3-hexafluoroisopropyl alcohol (HFIP), the Friedel–Crafts type cyclobutenylation reaction of several (hetero)aromatic compounds was smoothly proceeded by using gem-bis(triflyl)cyclobutenes as easily available sources of cyclobutenyl cations.