Synthetic studies on aphidicolane and stemodane diterpenes. I. Synthesis of (2'R*,4a'S*,8a'R*)-2',8a'-dimethyl-4a',5',8',8a'-tetrahydrospiro(2,5-cyclohexadiene-1,1'(2H)-naphthalene)-3'(4'H),4,6'(7'H)-trione.
摘要:
在氯化铜 (II) 的存在下,通过分解酚类 α-重氮酮 (9) 合成了标题化合物 (8),它可能是合成蚜虫烷和茎烷二萜的中间体。
The first nickel-catalyzed desymmetric hydrogenation has been achieved. With the Ni(OTf)2/(S,S)-Ph-BPE system, a series of γ,γ-disubstituted cyclohexadienones were transformed to the corresponding cyclohexenones with a chiral all-carbon quaternary center at the γ position in high yields (92% to 98%) and excellent enantioselectivities (92% to 99% ee). This catalytic system can also tolerate the desymmetric
首次实现了镍催化的不对称氢化。使用 Ni(OTf)2/(S,S)-Ph-BPE 系统,一系列 γ,γ-二取代环己二烯酮以高产率转化为相应的环己烯酮,其在 γ 位具有手性全碳四元中心( 92% 至 98%)和出色的对映选择性(92% 至 99% ee)。该催化体系还可以耐受螺碳环环己二烯酮的去对称反应,以产生相应的带有手性螺季碳的环己烯酮,收率高(94% 至 98%)和 ee 值(96% 至 99% ee)。此外,该方法为天然产物大麻吡酮 A 和 B 的中间体提供了一种高效、简洁的合成路线。
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
Synthesis of 4-alkyl-4-(4-methoxyphenyl)cyclohex-2-en-1-ones and 5-alkyl-5-phenyl-1,3-cyclohexadienes from bis(tricarbonylchromium)-coordinated biphenyls
作者:Reuben D. Rieke、Louis D. Schulte、Bryan T. Dawson、Sheng Sheng Yang
DOI:10.1021/ja00179a024
日期:1990.11
methyl iodide, and primary alkyl bromides, tosylates, and sulfates in a highly stereoselective and regioselective manner to form [μ-6-substituted-6-(η 6 -phenyl)(1−5-η 5 )-cyclohexadienyl] bis(tricarbonylchromium) anions
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.