- Enantiopure cis- and trans-2-(2-Aminocyclohexyl)phenols: Effective Preparation, Solid-State Characterization, and Application in Asymmetric Organocatalysis
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Effective synthesis of cis- and trans-2-(2-methoxyphenyl)cyclohexylamine as well as their multigram-scale optical resolution by diastereomeric salt formation with dibenzoyl tartaric acid have been described. Assignment of absolute configurations to the enantiomers has been made by X-ray crystallography. Starting from the resolved precursor, diverse aminoalkylphenols (AAPs) having primary, secondary, and tertiary amine group as well as a quaternary ammonium phenol have been prepared as potential bifunctional organocatalysts based on the cyclohexane backbone. We furthermore report herein that AAPs carrying a primary amine and a phenolic hydroxyl group can catalyze the direct aldol reaction with high activity and setereoselectivity, and thus up to 97 % yield, 90:10 syn/anti diastereomeric ratio, and 80 % enantiomeric excess can be achieved.
- Tezeren, Mustafa A.,Ye?il, Tolga A.,Zorlu, Yunus,Tilki, Tahir,Ertürk, Erkan
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p. 7017 - 7032
(2018/12/13)
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- Exploration of the diastereoselectivity in an unusual Grignard reaction and its application towards the synthesis of styryl lactones 7-: Epi -(+)-goniodiol and 8- epi -(-)-goniodiol
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An unusual diastereoselective Grignard reaction is explored, where the Grignard reagents are derived from 1,n-dihaloalkanes. A steric bias due to the presence of a quaternary centre adjacent to the acetonide ester at the benzylic position is responsible for the formation of an intramolecularly reduced product in almost quantitative yield. This steric hindrance is responsible for the diastereoselectivity observed with a variety of aromatic as well as aliphatic esters. The unusual Grignard reaction furnishes long chain secondary alcohols possessing a terminal olefin, which are synthetically important intermediates. As an application of this method, the diastereoselective synthesis of styryl lactones viz. 7-epi-(+)-goniodiol (29) and 8-epi-(-)-goniodiol (30) has been achieved.
- Chavan, Subhash P.,Khatod, Harshali S.,Das, Tamal,Vanka, Kumar
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p. 50721 - 50725
(2016/06/09)
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- The Barbier-Grignard-Type Arylation of Ketones and Unexpected Cross-Coupling of Phenolic Ketones using Unactivated Aryl Bromides
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A novel, highly versatile and efficient method has been developed for the Barbier-Grignard-type arylation of ketones and an unexpected cross-coupling of phenolic ketones was observed using unactivated bromides and magnesium in tetrahydrofuran/toluene at 96°C promoted by multicatalysts of cupric bromide (15 mol%), bismuth chloride (5 mol%) and silver bromide (10 mol%). The substituent and electronic effects on the reaction have been discussed. High yields of arylation and cross-coupling have been attained under mild conditions. A novel reasonable mechanism involving a quinone intermediate is proposed. The high chemical selectivity in the cross-coupling to the hydroxy group of phenolic ketones should help ketones find new applications.
- Wen, Yunming,Chen, Guifang,Huang, Shiqiang,Tang, Yu,Yang, Jun,Zhang, Yuanming
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p. 947 - 957
(2016/04/05)
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- Ni-catalysed, domino synthesis of tertiary alcohols from secondary alcohols
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The use of in situ generated (NHC)-Ni catalytic species (NHC = N-heterocyclic carbene) allows for the synthesis, in short reaction times, of a variety of tertiary alcohols from secondary alcohols through a domino oxidation-addition protocol.
- Berini, Christophe,Navarro, Oscar
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supporting information; experimental part
p. 1538 - 1540
(2012/02/16)
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- Synthesis and application of 2,6-bis(trifluoromethyl)-4-pyridyl phosphanes: The most electron-poor aryl phosphanes with moderate bulkiness
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The poor will be rich: BFPy phosphanes (see scheme) mimic the electronic and steric characters of P(C6F5)3 and PPh 3, respectively. These novel ligands showed a large ligand acceleration effect on Stille coupling, the Rh-catalyzed 1,2-addition of aryl boronic acid to unactivated ketones and the asymmetric arylation of N-tosylimine using phenylboronic acid. Copyright
- Korenaga, Toshinobu,Ko, Aram,Uotani, Kotaro,Tanaka, Yuki,Sakai, Takashi
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supporting information; experimental part
p. 10703 - 10707
(2012/01/04)
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- Synthesis and Anticonvulsant Activity of 1-Phenylcyclohexylamine Analogues
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Thirty-eight analogues of 1-phenylcyclohexylamine (PCA), a phencyclidine (PCP) derivative, were examined for their activities in the mouse maximal electroshock (MES) seizure test and in a motor-toxicity assay.In addition, we determined the binding affinities of the compounds for PCP acceptor sites in rat brain membranes labeled with -1-piperidine.Many of the analogues were protective against MES seizures (ED50s of 4-41 mg/kg, ip) and all of these compounds caused motor toxicity.The potencies in the motor toxicity and MES seizure tests showed a moderate correlation with the affinities for PCP sites.Several analogues exhibited a greater separation of potencies in the motor toxicity and MES seizure tests than did the parent compound PCA.These were obtained by (i) 3-methylation of the cyclohexyl ring trans to the phenyl ring, (ii) methoxylation at the ortho position on the phenyl ring, and (iii) contraction of the cyclohexane ring to form the corresponding cyclopentane.
- Thurkauf, Andrew,Costa, Brian de,Yamaguchi, Shun-ichi,Mattson, Mariena V.,Jacobson, Arthur E.,et al.
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p. 1452 - 1458
(2007/10/02)
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