- Vibrational spectroscopic studies of cocrystals and salts. 4. cocrystal products formed by benzylamine, α-methylbenzylamine, and their chloride salts
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The chloride salts formed by benzylamine and α-methylbenzylamine have been characterized using X-ray powder diffraction, differential scanning calorimetry, and infrared absorption spectroscopy. In addition, X-ray powder diffraction and differential scanning calorimetry have been used to establish formation or lack of formation of the 1:1 stoichiometric salt-cocrystal products containing the chloride salts and their respective free bases. For α-methylbenzylamine (which contains a single dissymmetric center), the chiral identities of the free bases and chloride salts were found to play a determining role as to whether a salt-cocrystal product could or could not be formed. It was found that a salt-cocrystal product could only be formed if the salt and free base were of opposite absolute configurations. For those systems where the existence of cocrystals was demonstrated, assignments were derived for the observed peaks in the infrared absorption spectra of the reactants and their products.
- Brittain, Harry G.
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- Rhodium-catalyzed asymmetric hydrogenation of unprotected NH imines assisted by a thiourea
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Asymmetric hydrogenation of unprotected NH imines catalyzed by rhodium/bis(phosphine)-thiourea provided chiral amines with up to 97% yield and 95% ee. 1HNMR studies, coupled with control experiments, implied that catalytic chloride-bound intermediates were involved in the mechanism through a dual hydrogen-bonding interaction. Deuteration experiments proved that the hydrogenation proceeded through a pathway consistent with an imine.
- Zhao, Qingyang,Wen, Jialin,Tan, Renchang,Huang, Kexuan,Metola, Pedro,Wang, Rui,Anslyn, Eric V.,Zhang, Xumu
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- Design and synthesis of 3,3′-triazolyl biisoquinoline N,N’-dioxides via Hiyama cross-coupling of 4-trimethylsilyl-1,2,3-triazoles
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A new strategy to effectively lock the conformation of substituents at the 3,3′-positions of axial-chiral biisoquinoline N,N’-dioxides was developed based on the strong dipole–dipole interaction between 1,2,3-triazole and pyridine N-oxide rings. The crystal structure and the DFT calculations of 3,3′-bis(1-benzyl-1H-1,2,3-triazole-4-yl)-1,1′-biisoquinoline N,N’-dioxide (3a) provided strong support for this strategy. Furthermore, we successfully demonstrated that readily available 4-trimethylsilyl-1,2,3-triazoles are viable nucleophiles for Hiyama cross-coupling.
- Sun, Shiyu,Reep, Carlyn,Zhang, Chenrui,Captain, Burjor,Peverati, Roberto,Takenaka, Norito
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- Giant Optical Activity and Second Harmonic Generation in 2D Hybrid Copper Halides
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Hybrid organic–inorganic metal halides have emerged as highly promising materials for a wide range of applications in optoelectronics. Incorporating chiral organic molecules into metal halides enables the extension of their unique optical and electronic properties to chiral optics. By using chiral (R)- or (S)-methylbenzylamine (R-/S-MBA) as the organic component, we synthesized chiral hybrid copper halides, (R-/S-MBA)2CuCl4, and investigated their optical activity. Thin films of this material showed a record anisotropic g-factor as high as approximately 0.06. We discuss the origin of the giant optical activity observed in (R-/S-MBA)2CuCl4 by theoretical modeling based on density functional theory (DFT) and demonstrate highly efficient second harmonic generation (SHG) in these samples. Our study provides insight into the design of chiral materials by structural engineering, creating a new platform for chiral and nonlinear photonic device applications of the chiral hybrid copper halides.
- Guo, Zhihang,Li, Junzi,Wang, Changshun,Liu, Rulin,Liang, Jiechun,Gao, Yang,Cheng, Jiaji,Zhang, Wenjing,Zhu, Xi,Pan, Ruikun,He, Tingchao
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- The fate of the tert-butylsulfinyl auxiliary after acid-promoted cleavage-a method for recycling t-BuSONH2
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Ellman's chiral auxiliary is converted into tert-butylsulfinyl chloride on sulfinamide deprotection with HCl and can be recovered in high yield upon treatment with ammonia. The enantiopure auxiliary can be obtained by trapping the sulfinyl chloride with a chiral alcohol followed by treatment of the resulting sulfinate ester with LiNH2.
- Aggarwal, Varinder K.,Barbero, Nekane,McGarrigle, Eoghan M.,Mickle, Greg,Navas, Raquel,Suárez, José Ramón,Unthank, Matthew G.,Yar, Muhammad
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- Development of a new synthesis approach for S-pregabalin by optimizing the preparation stages
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In the present study, we aimed to optimize the synthesis stages of S-pregabalin ((S)-3-(aminomethyl)-5-methylhexanoic acid), a well-known anticonvulsant drug. We used appropriate solvents and compounds to reach a straightforward and applicable method. The advantages of this research were avoiding use of expensive and environment pollutant reagents and solvents, and also using a recoverable reagent. Discarding prevention of the intermediates and reagents besides attaining a higher yield of the obtained product were the additional achievements. All structures were characterized by FT-IR, 1H NMR, and the purity of S-pregabalin was evaluated using the HPLC assay.
- Mansoori, Arsalan,Zahednezhad, Fahimeh,Bavili Tabrizi, Ahad,Shahbazi Mojarrad, Javid
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- Highly Efficient Spin-Filtering Transport in Chiral Hybrid Copper Halides
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Chiral Pb(Sn)-I hybrid organic–inorganic perovskites exhibit outstanding chiral-induced spin selectivity (CISS) performance, but the nontoxic lead-free hybrid materials with high stability are still greatly desired for spin filtering in spintronic applica
- Cao, Hui,He, Ruilin,He, Wanli,Lu, Ying,Pan, Feng,Song, Cheng,Wang, Dong,Wang, Qian,Yang, Xia,Yang, Zhou,Zhou, Foxin
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supporting information
p. 23578 - 23583
(2021/10/04)
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- Chiral Bronsted Acids Catalyze Asymmetric Additions to Substrates that Are Already Protonated: Highly Enantioselective Disulfonimide-Catalyzed Hantzsch Ester Reductions of NH-Imine Hydrochloride Salts
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While imines are frequently used substrates in asymmetric Bronsted acid catalysis, their corresponding salts are generally considered unsuitable reaction partners. Such processes are challenging because they require the successful competition of a catalytic amount of a chiral anion with a stoichiometric amount of an achiral one. We now show that enantiopure disulfonimides enable the asymmetric reduction of N-H imine hydrochloride salts using Hantzsch esters as hydrogen source. Our scalable reaction delivers crystalline primary amine salts in great efficiency and enantioselectivity and the discovery suggests potential of this approach in other Bronsted acid catalyzed transformations of achiral iminium salts. Kinetic studies and acidity data suggest a bifunctional catalytic activation mode.
- Wakchaure, Vijay N.,Obradors, Carla,List, Benjamin
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supporting information
p. 1707 - 1712
(2020/08/28)
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- Synthesis of novel chiral guanidine catalyst and its application in the asymmetric Pictet-Spengler reaction
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A new chiral guanidine catalyst has been synthesized by the reaction of (R)-1-(1-phenylethyl)guanidine and 2,3-diphenylcycloprop-2-enone. The catalyst was evaluated for the Pictet-Spengler reaction in which tetrahydro-β-carbolines were obtained in good yi
- Ahmad, Saeed,Shukla, Lakshmi,Szawka?o, Joanna,Roszkowski, Piotr,Maurin, Jan K.,Czarnocki, Zbigniew
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- Synthesis and extraction properties of some lariat ethers derived from the spontaneously resolved guaifenesin, 3-(2-methoxyphenoxy)propane-1,2-diol
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Capable of spontaneous resolution rac-3-(2-methoxyphenoxy)propane-1,2-diol, guaifenesin 1 has been proposed as a cheap and readily available enantiopure precursor for the synthesis of nonracemic crown ethers having ligating OAr and OMe arms (lariat ethers). The crowns studied failed to form stable host/guest complexes with amine hydrochloride salts; the effective complexation was achieved using hexafluorophosphate salts. Moderate enantiomeric recognition of R*NH2·HPF6 was achieved with the lariat ethers 11c. As a whole, the enantioselectivity of the extraction is inversely related to the extractive power of the lariat ether. ARKAT-USA, Inc.
- Bredikhina, Zemfira A.,Eliseenkova, Rimma M.,Fayzullin, Robert R.,Novikova, Viktorina G.,Kharlamov, Sergey V.,Sharafutdinova, Dilyara R.,Latypov, Shamil K.,Bredikhin, Alexander A.
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experimental part
p. 16 - 32
(2011/09/21)
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- Enantioselective hydrogenation of N-H imines
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(Figure Presented) N-H ketoimines 3a-3v are readily prepared in high yield via organometallic addition to nitriles and isolated as corresponding bench-stable hydrochloride salts. Homogeneous asymmetric hydrogenation of unprotected N-H ketoimines 3a-3v usi
- Hou, Guohua,Gosselin, Francis,Li, Wei,McWilliams, J. Christopher,Sun, Yongkui,Weisel, Mark,O'Shea, Paul D.,Chen, Cheng-Yi,Davies, Ian W.,Zhang, Xumu
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supporting information; experimental part
p. 9882 - 9883
(2009/12/06)
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- Iridium/monodentate phosphoramidite catalyzed asymmetric hydrogenation of N-aryl imines
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(Chemical Equation Presented) Asymmetric hydrogenation of N-aryl acetophenone imines using iridium/PipPhos leads to very high enantioselectivities up to >99percent depending on the presence of electron-donating substituents in the 2-, 3-, and 5-position of the aryl ring. If the substituent is 2-methoxy, the resultant secondary amines are easily oxidatively deprotected using trichloroisocyanuric acid to give the primary amines ingood yield with full retention of enantioselectivity.
- Mrsic, Natasa,Minnaard, Adriaan J.,Feringa, Ben L.,Vries, Johannes G. de
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supporting information; experimental part
p. 8358 - 8359
(2009/10/23)
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- Reversal of diastereofacial selectivity in hydride reductions of N-tert-butanesulfinyl imines
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A variety of N-tert-butanesulfinyl imines were reduced with NaBH 4 in THF containing 2% water to provide the corresponding secondary sulfinamides in high yield and diastereoselectivity. By using the same sulfinyl imine starting materials and changing the reductant to L-Selectride, the stereoselectivity could be efficiently reversed to afford the opposite product diastereomer in high yield and selectivity.
- Colyer, John T.,Andersen, Neil G.,Tedrow, Jason S.,Soukup, Troy S.,Faul, Margaret M.
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p. 6859 - 6862
(2007/10/03)
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- Multicomponent one-pot procedure for the synthesis of free α-chiral amines from aldehydes
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The synthesis of free a-chiral amines by a one-pot multi-component procedure from commercially available starting materials is described. This enantioselective reaction involves a catalytic asymmetric addition of dialkylzinc reagents to N-diphenylphosphin
- Cote, Alexandre,Charette, Andre B.
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p. 10864 - 10867
(2007/10/03)
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- Orthoacylimines: A new class of chiral auxiliaries for nucleophilic addition of organolithium reagents to imines
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A new class of orthoacylimine-derived chiral auxiliaries has been synthesized and tested in the nucleophilic addition of organolithium reagents to imines. The precursors can be prepared by an aza-Wittig reaction between the corresponding orthoacyl azide and a variety of aldehydes in the presence of trialkylphosphines. The nucleophilic addition of organolithium reagents led to the addition products in good yields and with good to excellent diastereoselectivities (from 85:15 to 99:1). The chiral, nonracemic secondary amines could be readily obtained under mild hydrolytic condition. Furthermore, the chiral auxiliary can be recovered in quantitative yield and reconverted to the starting orthoacyl azide precursor. This method was applied to the synthesis of (S)-t-leucine.
- Boezio, Alessandro A.,Solberghe, Geoffrey,Lauzon, Caroline,Charette, Andre B.
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p. 3241 - 3245
(2007/10/03)
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- Resolution of chiral aliphatic and arylalkyl amines using immobilized Candida antarctica lipase and isolation of their R- and S-enantiomers
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The resolution of chiral aliphatic and arylalkyl amines in high enantiomeric excess (up to 97.5% ee for the R-enantiomers and up to 99.9% ee for the S-enantiomers) and good yield (50-80%) using immobilized Candida antarctica lipase and ethyl acetate as acyl donor has been demonstrated. A second resolution on the Ramine increased the enantiomeric excess to more than 99.5% (up to 99.9%).
- Davis,Durden
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p. 569 - 578
(2007/10/03)
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- Asymmetric synthesis of chiral amines by highly diastereoselective 1,2- additions of organometallic reagents to N-tert-butanesulfinyl imines
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High yielding and highly diastereoselective methods for 1,2-additions of organometallic reagents to N-tert-butanesulfinyl aldimines (2) and N-tert- butanesulfinyl kerimines (3) are described. The additions of alkyl, aryl, alkenyl, and allyl carbanions to a diverse set of imines with different steric and electronic properties are demonstrated. Acidic methanolysis of the sulfinamide products (4 and 6) delivers highly enantioenriched α-branched and α,α-dibranched amines. Since a broad range of sulfinyl imines are easily accessible from aldehydes and ketones, a wide variety of enantioentriched amines may be prepared.
- Cogan, Derek A.,Liu, Guangcheng,Ellman, Jonathan
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p. 8883 - 8904
(2007/10/03)
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