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.
PtBr<sub>2</sub>-Catalyzed Consecutive Enyne Metathesis−Aromatization of 1-(1-Methoxy-but-3-enyl)-2-(1-alkynyl)benzenes: Dual Role of the Pt Catalyst
作者:Gan B. Bajracharya、Itaru Nakamura、Yoshinori Yamamoto
DOI:10.1021/jo048273q
日期:2005.2.1
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.
Fe2(CO)9-mediated [5+1] cycloaddition of vinylcyclopropanes and CO for the synthesis of α, β-cyclohexenones
A Fe2(CO)9-mediated [5+1] cycloaddition of vinylcyclopropanes (VCPs) and CO to α, β-cyclohexenones has been developed. The reaction can tolerate aryl and aliphatic groups at the α-position of VCPs, while VCP substrates with vinyl or alkynyl substitutions are not suitable ones. In addition, this reaction can also be used to synthesize bicyclic rings if an aryl group is attached to the vinyl moiety of