- Reductive amination of ketonic compounds catalyzed by Cp*Ir(III) complexes bearing a picolinamidato ligand
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Cp*Ir complexes bearing a 2-picolinamide moiety serve as effective catalysts for the direct reductive amination of ketonic compounds to give primary amines under transfer hydrogenation conditions using ammonium formate as both the nitrogen and hydrogen source. The clean and operationally simple transformation proceeds with a substrate to catalyst molar ratio (S/C) of up to 20,000 at relatively low temperature and exhibits excellent chemoselectivity toward primary amines.
- Tanaka, Kouichi,Miki, Takashi,Murata, Kunihiko,Yamaguchi, Ayumi,Kayaki, Yoshihito,Kuwata, Shigeki,Ikariya, Takao,Watanabe, Masahito
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p. 10962 - 10977
(2019/09/03)
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- Enantioselective acylation of rac-2-phenylcycloalkanamines catalyzed by lipases
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The kinetic resolution of some 2-phenylcycloalkanamines was performed by means of aminolysis reactions catalyzed by lipases, with Kazlauskas' rule being obeyed in all cases. The size of the ring and the stereochemistry of the stereogenic centers of the amines had a strong influence on both the enantiomeric ratio and the reaction rate of these aminolysis processes. Lipase B from Candida antarctica (CAL-B) showed excellent enantioselectivities toward trans-2-phenylcyclohexanamine in a variety of reaction conditions (E >150), whereas lipase A from C. antarctica (CAL-A) was the best catalyst for the acylation of cis-2-phenylcyclohexanamine (E = 34) and trans-2- phenylcyclopropanamine (E = 9).
- Gonzalez-Sabin, Javier,Gotor, Vicente,Rebolledo, Francisca
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p. 3070 - 3076
(2007/10/03)
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- 2-Amino-2-oxazolines as subtype selective α2 adrenoceptor agonists
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Cyclohexylamino oxazoline I (AGN 190837), an analogue of 2 (Bay a6781), is a potent α2 adrenoceptor agonist. On the basis of a design generated by receptor-ligand modeling, a number of cyclohexyl and norbornyl analogues were synthesized wherein the propyl group of I was replaced by phenylalkyl subsituents. This resulted in compound 6 being an α(2c) selective agonist, as well as 7 and 9 being α(2a)/α(2c) selective.
- Wong, Wai C.,Sun, Wanying,Cui, Weili,Chen, Yuewen,Forray, Carlos,Vaysse, Pierre J.-J.,Branchek, Theresa A.,Gluchowski, Charles
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p. 1699 - 1704
(2007/10/03)
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- Carbon-Skeletal Anionic Rearrangements of Tertiary Benzylic Amines: Geometric and Electronic Requirements for Generating the Spiroazacyclopropane Intermediate
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In order to determine the scope and mechanism for the base-promoted rearrangement of tertiary amines, a wide variety of benzylic amines were treated with n-BuLi in THF or TMEDA, n-BuLi-KO-t-Bu mixtures, or KH.The following amines were examined: benzyldimethylamine, benzylmethylphenylamine, benzyldiphenylamine, N-benzylcarbazole, N-benzyl-1,2,3,4-tetrahydrocarbazole, N-benzyl-1,1a,2,3,4,4a-cis-hexahydrocarbazole, N-(2-phenylethyl)carbazole, N-(3-phenylpropyl)carbazole, N-(2-chloroethyl)carbazole, N-benzyl-9,9-dimethyl-9,10-dihydroacridine, N-benzyl-o,o'-iminodibenzyl, 9-(diphenylamino)fluorene, 9-anilino-9-phenylfluorene, 9-(methylphenylamino)fluorene, and diphenyl(diphenylmethyl)amine.In certain cases, ethylation products were obtained from the interaction of intermediate carbanions with ethylene generated by the decomposition of THF.The results are interpreted in terms of intramolecular shifts of aryl groups from nitrogen to benzylic carbon proceeding by way of a bridging aryl transition state or intermediate.
- Eisch, John J.,Dua, Suresh K.,Kovacs, Csaba A.
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p. 4437 - 4444
(2007/10/02)
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- ORGANOBORANES FOR SYNTHESIS. 7. AN IMPROVED GENERAL SYNTHESIS OF PRIMARY AMINES FROM ALKENES via HYDROBORATION-ORGANOBORANE CHEMISTRY
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Triorganylboranes, R3B, and diorganylborinicesters, R2BOR', react readily with preformed chloramine or hydroxylamine-O-sulfonic acid to produce the corresponding primary amines, RNH2.However, the product of the reaction following hydrolysis is the boronic acid, RB(OH)2, limiting the yield to 67percent for R3B and to 50percent for R2BOR'.This problem has now been overcome with the help of lithium dimethylborohydride, readily converted in situ to dimethylborane.The hydroboration of representative alkenes by dimethylborane provides the corresponding monoorganyldimethylborane, RMe2B.Treatment of this intermediate with hydroxylamine-O-sulfonic acid provides the desired amines, RNH2, in isolated yields of 73percent to 95percent.The reaction proceeds with complete retention, reproducing the precise structure of the organic group in the organoboranes, RMe2B.
- Brown, Herbert C.,Kim, Kee-Won,Srebnik, Morris,Singaram, Bakthan
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p. 4071 - 4078
(2007/10/02)
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