50919-07-8Relevant articles and documents
Optical Resolution of 1-(3-Methoxyphenyl)ethylamine with Enantiomerically Pure Mandelic Acid, and the Crystal Structure of Less-Soluble Diastereomeric Salt
Sakai, Kenichi,Hashimoto, Yukihiko,Kinbara, Kazushi,Saigo, Kazuhiko,Murakami, Hisamichi,Nohira, Hiroyuki
, p. 3414 - 3418 (1993)
Enantiomerically pure 1-(3-methoxyphenyl)ethylamine (1), which is a key intermediate of new phenyl carbamate drugs, was obtained by a diastereomeric method with high resolution efficiency (E) by using enantiomerically pure mandelic acid (2) as a resolving agent.The first crystallization of the mixture of diastereomeric salts from methanol gave a less-soluble diastereomeric salt in 70percent yield with 99percent diastereomeric excess.Recrystallization of the salt from 2-propanol gave (R)-1*(R)-2 in 97percent yield with 100percent diastereomeric excess (total E=68percent).The crystal structure of the less-soluble diastereomeric salt, (R)-1*(R)-2, was determined by X-ray crystallography.The crystal data are: Monoclinic, space group P21, a=12.642(4), b=5.890(2), c=10.855(4) Angstroem, β=103.68(3) deg, V=785.4(5) Angstroem3, Z=2, R=0.058 for 1450 unique reflections.The X-ray crystallography revealed that the high resolution efficiency was due to a layer-like arrangement of the enantiomerically pure acids, of which two layers sandwiched a layer of the amines by hydrogen bonds, as well as the helical column formed by hydrogen bonds between the acids and the amines, as observed for the less-soluble diastereomeric salt of 1-phenylethylamine with mandelic acid.
Oxidation Under Reductive Conditions: From Benzylic Ethers to Acetals with Perfect Atom-Economy by Titanocene(III) Catalysis
Funk, Pierre,Richrath, Ruben B.,Bohle, Fabian,Grimme, Stefan,Gans?uer, Andreas
, p. 5482 - 5488 (2021/02/03)
Described here is a titanocene-catalyzed reaction for the synthesis of acetals and hemiaminals from benzylic ethers and benzylic amines, respectively, with pendant epoxides. The reaction proceeds by catalysis in single-electron steps. The oxidative addition comprises an epoxide opening. An H-atom transfer, to generate a benzylic radical, serves as a radical translocation step, and an organometallic oxygen rebound as a reductive elimination. The reaction mechanism was studied by high-level dispersion corrected hybrid functional DFT with implicit solvation. The low-energy conformational space was searched by the efficient CREST program. The stereoselectivity was deduced from the lowest lying benzylic radical structures and their conformations are controlled by hyperconjugative interactions and steric interactions between the titanocene catalyst and the aryl groups of the substrate. An interesting mechanistic aspect is that the oxidation of the benzylic center occurs under reducing conditions.
General and selective synthesis of primary amines using Ni-based homogeneous catalysts
Beller, Matthias,Chandrashekhar, Vishwas G.,Jagadeesh, Rajenahally V.,Jiao, Haijun,Murugesan, Kathiravan,Wei, Zhihong
, p. 4332 - 4339 (2020/05/18)
The development of base metal catalysts for industrially relevant amination and hydrogenation reactions by applying abundant and atom economical reagents continues to be important for the cost-effective and sustainable synthesis of amines which represent highly essential chemicals. In particular, the synthesis of primary amines is of central importance because these compounds serve as key precursors and central intermediates to produce value-added fine and bulk chemicals as well as pharmaceuticals, agrochemicals and materials. Here we report a Ni-triphos complex as the first Ni-based homogeneous catalyst for both reductive amination of carbonyl compounds with ammonia and hydrogenation of nitroarenes to prepare all kinds of primary amines. Remarkably, this Ni-complex enabled the synthesis of functionalized and structurally diverse benzylic, heterocyclic and aliphatic linear and branched primary amines as well as aromatic primary amines starting from inexpensive and easily accessible carbonyl compounds (aldehydes and ketones) and nitroarenes using ammonia and molecular hydrogen. This Ni-catalyzed reductive amination methodology has been applied for the amination of more complex pharmaceuticals and steroid derivatives. Detailed DFT computations have been performed for the Ni-triphos based reductive amination reaction, and they revealed that the overall reaction has an inner-sphere mechanism with H2metathesis as the rate-determining step.
