- Synthesis of a phosphapyracene via metal-mediated cyclization: Structural and reactivity effects of acenaphthene precursors
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Metal-mediated synthesis of a new heterocycle, 1-phenyl-phosphapyracene (Ph-4, Ph-PyraPhos), by tandem phosphination/cyclization of peri-substituted 5-bromo-6-chloromethylacenaphthene (3) was investigated for comparison to Pt-catalyzed formation of 1-phosphaacenaphthenes (2, AcePhos) from the analogous naphthalene precursor (1). Reaction of PH2Ph with 3, NaOSiMe3 and a Cu catalyst gave Ph-4; a Pt catalyst yielded PHPh(CH2Ar) (Ph-11, Ar = 5-Br-acenaphthyl). Deprotonation of a complex of this secondary phosphine, [Pt((R,R)-Me-DuPhos)(Ph)(PHPh(CH2Ar))][PF6] (17), generated the phosphido intermediate Pt((R,R)-Me-DuPhos)(Ph)(PPhCH2Ar) (Ph-8), which cyclized to give [Pt((R,R)-Me-DuPhos)(Ph)(Ph-PyraPhos)][PF6] (18). Treatment of Ph-8 with silver triflate gave 18 and the cyclometalated phosphine complex [Pt((R,R)-Me-DuPhos)(κ2-(P,C)-5-Ph2PCH2-6-C12H8)][PF6] (21), which might form via Pt(iv) intermediates. The effects of the added "ace" bridge on structure and reactivity are discussed.
- Wang, Ge,Guino-O, Marites A.,Glueck, David S.,Golen, James A.,Daley, Christopher J.A.,Rheingold, Arnold L.
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- Pd-catalyzed C4-Dearomative Allylation of Benzyl Ammoniums with Allyltributylstannane
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A dearomative C4-allylation of benzyl ammoniums with allyltributylstannane by a palladium catalysis is described. A triarylphosphine-ligated palladium catalyst, which is capable of cleaving benzylic CN bonds, realized facile dearomative reactions with C4 selectivity. Combined with precedented C2- A nd C3-selective functionalizations of benzyl amine derivatives, the present reaction can provide a new synthetic option for the synthesis of multi-substituted alicyclic compounds as well as aromatic compounds.
- Kayashima, Yuki,Komatsuda, Masaaki,Muto, Kei,Yamaguchi, Junichiro
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supporting information
p. 836 - 839
(2020/07/23)
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- Phase-Transfer Catalysis in Electrophilic Substitution Reactions. V. Reactivities of Aromatic Compounds in Chloromethylation under Conditions of Phase-Transfer Catalysis
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Regioselectivity of chloromethylation of aromatic compounds under conditions of phase-transfer catalysis linearly correlates with the ?+Ar constants, the correlations significantly depending on the catalyst; moreover, the nature of the catalyst is the factor that governs the fine mechanism of the reaction.Only one of the two detected reaction mechanisms yields chloromethyl derivatives as the final products.
- Kachurin, O. I.,Velichko, L. I.,Zaraiskaya, N. A.,Zaraiskii, A. P.
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p. 657 - 659
(2007/10/03)
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