Asymmetric Synthesis of Remote Quaternary Centers by Copper-Catalyzed Desymmetrization: An Enantioselective Total Synthesis of (+)-Mesembrine
作者:Apparao Bokka、James X. Mao、John Hartung、Steven R. Martinez、Justin A. Simanis、Kwangho Nam、Junha Jeon、Xiaoqiang Shen
DOI:10.1021/acs.orglett.8b02084
日期:2018.9.7
Catalytic asymmetric syntheses of remote quaternary stereocenters have been developed by copper-catalyzed 1,4-hydrosilylation of γ,γ-disubstituted cyclohexadienones. A variety of cyclohexenones have been synthesized in good yield and excellent enantioselectivity. Versatile 2-silyloxy diene intermediates bearing γ,γ-disubstituted all carbon stereogenic centers can be isolated from the mild reaction
the corresponding cyclohexenones 4 with a remote chiral all‐carbon quaternary center at the γ position is described. Chiral rhodium–bis(oxazolinyl)phenyl complexes 1 were effective catalysts for this transformation. This catalytic system was extended to the asymmetric transformation of spirocarbocyclic cyclohexadienones 5 to give the corresponding products 6 with highenantiomeric ratios.
Asymmetric organocatalytic desymmetrization of 4,4-disubstituted cyclohexadienones at high pressure: a new powerful strategy for the synthesis of highly congested chiral cyclohexenones
A highly diastereoselective and enantioselective method for the asymmetric desymmetrization of 4,4-disubstituted cyclohexadienones using the Michael addition reaction of malonates under catalysis with the primary amine-thiourea conjugate catalyst and PPY at high pressure was developed.
Synthesis of <i>meta</i>-arylphenol derivatives <i>via</i> acid-promoted rearrangement of cyclohexadienones
作者:Hongyan Xie、Minxiang Zhang、Xueyu Fang、Zhaohua Yan、Hua Yao
DOI:10.1039/d3ob01363d
日期:——
A highly effective strategy for the synthesis of meta-arylphenol derivatives through the selective rearrangement of 4-alkyl-4-aryl-2,5-cyclohexadienones under metal-free conditions was developed, in which acid-promoted [1,2]-migration of the aryl group at C-4 occurred exclusively when the alkyl group at C-4 was a methyl group. Treatment of 4-methyl-4-aryl-2,5-cyclohexadienones with 37% HCl in Ac2O
Desymmetrization of Cyclohexadienones Containing a Quaternary γ-Carbon Atom by Conjugate Addition of Boron Nucleophiles
作者:Zhi-Yuan Zhao、Ming Cui、Anne A. Poletti、Elisabeth Irran、Martin Oestreich
DOI:10.1021/acscatal.3c04725
日期:2024.1.5
A highlyenantio- and diastereoselective copper-catalyzed conjugate monoborylation of γ,γ-disubstituted cyclohexadienone derivatives is reported. Two contiguous stereocenters are generated in this group-selective reaction, one at the formed boron-bearing carbon atom in a neopentylic position and one at the quaternary carbon atom. A subsequent 1,4-addition of a boron nucleophile to the remaining α,β-unsaturated