PtBr2-Catalyzed Consecutive Enyne Metathesis−Aromatization of 1-(1-Methoxy-but-3-enyl)-2-(1-alkynyl)benzenes: Dual Role of the Pt Catalyst
摘要:
1,7-Enynes 1, connected through an aromatic ring and bearing a leaving methoxy group at the 4-position, underwent the PtBr2-catalyzed enyne metathesis followed by aromatization in one pot to afford vinyl naphthalenes 3 in good to acceptable yields. The cyclobutene intermediate 11a and another intermediate 2a were isolated, indicating that PtBr2 acts as a dual role catalyst: (1) as a transition metal catalyst, it induces the eryne metathesis to produce 11a starting from 1a, and (2) as a Lewis acid catalyst, it facilitates elimination of MeOH from 2a to give the aromatized product 3a.
B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>-Catalyzed Hydrosilylation of Vinylcyclopropanes
作者:Peng-Wei Long、Tao He、Martin Oestreich
DOI:10.1021/acs.orglett.0c02751
日期:2020.9.18
reported. For the majority of VCPs, little or no ring opening of the cyclopropyl unit is observed. Conversely, for VCPs with bulky R groups, such as ortho-substituted aryl rings or branched alkyl residues, ring opening is the exclusive reaction pathway. This finding is explained by the thwarted hydride delivery to a sterically shielded, β-silicon-stabilized cyclopropylcarbinyl cation intermediate.
据报道,强硼路易斯酸B(C 6 F 5)3催化乙烯基环丙烷(VCP)的硅氢化。对于大多数VCP,观察到很少或没有环丙基单元的开环。相反,对于具有庞大R基团的VCP,例如邻位取代的芳基环或支链烷基残基,开环是唯一的反应途径。这一发现可以通过阻止氢化物向空间屏蔽的,β-硅稳定的环丙基羰基阳离子中间物的传递来解释。
Radical 1,5-Chloropentafluorosulfanylation of Unactivated Vinylcyclopropanes and Transformation into α-SF<sub>5</sub> Ketones
作者:Fang-Fang Feng、Jun-An Ma、Dominique Cahard
DOI:10.1021/acs.joc.1c01886
日期:2021.10.1
5-chloropentafluorosulfanylation of vinyl cyclopropanes (VCPs) initiated by Et3B/O2 affords allylic pentafluorosulfanyl/homoallylic chloride products through the ring-strain release of the cyclopropane. The VCP substitution pattern was investigated. The utility of this reaction was illustrated in post-transformation of the C═C bond by ozonolysis, giving access to valuable α-SF5 carbonyl compounds.