- Dynamic Kinetic Resolution of Alcohols by Enantioselective Silylation Enabled by Two Orthogonal Transition-Metal Catalysts
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A nonenzymatic dynamic kinetic resolution of acyclic and cyclic benzylic alcohols is reported. The approach merges rapid transition-metal-catalyzed alcohol racemization and enantioselective Cu-H-catalyzed dehydrogenative Si-O coupling of alcohols and hydrosilanes. The catalytic processes are orthogonal, and the racemization catalyst does not promote any background reactions such as the racemization of the silyl ether and its unselective formation. Often-used ruthenium half-sandwich complexes are not suitable but a bifunctional ruthenium pincer complex perfectly fulfills this purpose. By this, enantioselective silylation of racemic alcohol mixtures is achieved in high yields and with good levels of enantioselection.
- Oestreich, Martin,Seliger, Jan
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supporting information
p. 247 - 251
(2020/10/29)
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- Self-assembled organic-inorganic hybrids: Synthesis, structural, third-order nonlinear optical properties and Hirshfeld surface analysis of bis(1,2,3,4-tetrahydroisoquinolin-2-ium) hexahalostannate(IV)
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Two organic-inorganic hybrids viz., bis(1,2,3,4-tetrahydroisoquinolin-2-ium) hexachlorostannate(IV) (1) and bis(1,2,3,4-tetrahydroisoquinolin-2-ium) hexabromostannate(IV) (2) were synthesized and confirmed by single-crystal X-ray diffraction analysis. The optical properties of the compounds were studied by diffuse reflectance and photoluminescence spectral studies. The thermal behaviour of the compounds was determined by thermo gravimetric (TG) and differential thermal analysis (DTA) concerning the temperature. The significant third-order nonlinear optical response shown by the compounds is disclosed by the Z-scan studies. The surface morphology and the elemental composition of the compounds were studied by scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) analyses. Bond valence sum (BVS) calculation confirmed the formal oxidation state of tin to be +4. Check continuous symmetry measure (CSM) calculation on SnX62? (X=Cl, Br) yields a value significantly near to the perfect octahedral geometry of the anions. The intermolecular interactions and their quantity contributions in the crystal packing were studied by Hirshfeld analysis and fingerprint plots.
- Ahamed, S. Rafi,Balakrishnan, C.,Dhanalakshmi, M.,Parthiban, S.,Vinitha, G.
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- Direct Preparation of Amides from Amine Hydrochloride Salts and Orthoesters: A Synthetic and Mechanistic Perspective
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The conversion of a wide range of primary and secondary aliphatic and a few arylamine hydrochloride salts to their corresponding acetamides with trimethyl orthoacetate is described. Mechanistic studies using NMR and gas chromatography-mass spectrometry techniques indicate these reactions proceed via an O-methylimidate intermediate that undergoes in situ demethylation by chloride, affording the corresponding acetamides. Synthetically, this reaction represents a practical, high-yielding protocol with a simple workup for the rapid conversion of amine hydrochloride salts to acetamides.
- Di Grandi, Martin J.,Bennett, Caitlin,Cagino, Kristen,Muccini, Arnold,Suraci, Corey,Saba, Shahrokh
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supporting information
p. 2601 - 2607
(2015/11/28)
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- Straightforward access to cyclic amines by dinitriles reduction
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1,1,3,3-Tetramethyldisiloxane (TMDS) and polymethylhydrosiloxane (PMHS), when associated with titanium(IV) isopropoxide, provide two convenient systems for the reduction of nitriles into the corresponding primary amines. Kinetics of the two systems have been studied by 1H NMR and demonstrated that reduction with PMHS occurs faster than with TMDS. These two titanium-based systems reduce both aromatic and aliphatic nitriles in the presence of Br, CC, NO2, OH, and cyclopropyl-ring. In the case of cyclopropyl-nitriles, the formation of secondary amines, which come from an intermolecular reductive alkylation reaction was observed. This result was exploited for the reduction of dinitriles, which led, in one-step, to azepane, piperidine, pyrrolidine, and azetidine derivatives through an intramolecular reductive alkylation reaction.
- Laval, Stéphane,Dayoub, Wissam,Pehlivan, Leyla,Métay, Estelle,Favre-Reguillon, Alain,Delbrayelle, Dominique,Mignani, Gérard,Lemaire, Marc
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supporting information
p. 975 - 983
(2014/01/23)
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- New supramolecular triorganotin(IV) dithiocarboxylates as potential antibacterial agents
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Four triorganotin derivatives of general formula C10H 10NS2SnR3,, where R = CH3 (1), C4H9 (2), C6H11 (3), and C6H5 (4), have been synthesized by the metathesis reaction of 1,2,3,4-tetrahydroisoquinolnium salt of ligand with triorganotin(IV) chloride in the 1:1 ratio. These complexes were characterized by elemental analysis, Raman, IR, multinuclear NMR (1H, 13C, and 119Sn), and mass spectrometry. The crystal structure confirmed a supramolecular zig-zag chain structure mediated by S-H (2.968 A) for complex 4 with the central Sn atom exists in a distorted trigonal bipyramidal geometry. A subsequent antibacterial study indicates that the compounds are biologically active.
- Zia-Ur-Rehman,Muhammad, Niaz,Shah, Afzal,Ali, Saqib,Khan, Ezzat
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p. 560 - 567
(2013/01/15)
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- Photochemical deprotection of 3′,5′-dimethoxybenzoin (DMB) carbamates derived from secondary amines
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Treatment of secondary amines with a (dimethoxybenzoin)carbonylimidazolium salt provides dimethoxybenzoin carbamates that can be deprotected photochemically.
- Pirrung, Michael C.,Huang, Chia-Yu
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p. 5883 - 5884
(2007/10/02)
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- THE SYNTHESIS OF SOME ALCOHOLS DERIVED FROM 1,2,3,4-TETRAHYDROISOQUINOLINE AND FROM 1,2,3,4-TETRAHYDROQUINOLINE
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Reduction of ethyl ester of ω-(1,2,3,4-tetrahydro-2-isoquinolyl)alkanoic acids IVa-e by means of LiAlH4 was used for the preparation of corresponding primary alcohols Ia-e. 6-(1,2,3,4-tetrahydro-2-isoquinolyl)-1-hexanol (Ie) was also obtained on reduction of ester amide VII.Reduction of 2-(2-hydroxypropanoyl)-1,2,3,4-tetrahydroisoquinoline (V) with LiAlH4 gave secondary alcohol II; in the quinoline series alcohol IIIa was obtained in a similar manner by reduction of ethyl 3-(1,2,3,4-tetrahydro-1-quinolyl)propanoate (IIIb).
- Ferles, Miloslav,Silhankova, Alexandra,Kafka, Stanislav,Taufmann, Petr,Motacek, Tomas
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p. 1759 - 1764
(2007/10/02)
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