- Preparation and reactivity of terminal gold(i) amides and phosphides
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Nucleophilic terminal gold(i) amides have been prepared and their reactivity toward a variety of electrophiles has been explored. For the first time these frequently proposed intermediates were isolated and shown to be unreactive in the amination of π-bonds. The first crystallographically determined terminal group 11 metal phosphide was also synthesized. Preliminary DFT studies have been conducted to understand the structure and reactivity of these complexes.
- Johnson, Miles W.,Shevick, Sophia L.,Toste, F. Dean,Bergman, Robert G.
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- BF3·Et2O as a metal-free catalyst for direct reductive amination of aldehydes with amines using formic acid as a reductant
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A versatile metal- and base-free direct reductive amination of aldehydes with amines using formic acid as a reductant under the catalysis of inexpensive BF3·Et2O has been developed. A wide range of primary and secondary amines and diversely substituted aldehydes are compatible with this transformation, allowing facile access to various secondary and tertiary amines in high yields with wide functional group tolerance. Moreover, the method is convenient for the late-stage functionalization of bioactive compounds and preparation of commercialized drug molecules and biologically relevant N-heterocycles. The procedure has the advantages of simple operation and workup and easy scale-up, and does not require dry conditions, an inert atmosphere or a water scavenger. Mechanistic studies reveal the involvement of imine activation by BF3and hydride transfer from formic acid.
- Fan, Qing-Hua,Liu, Xintong,Luo, Zhenli,Pan, Yixiao,Xu, Lijin,Yang, Ji,Yao, Zhen,Zhang, Xin
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supporting information
p. 5205 - 5211
(2021/07/29)
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- Desymmetric enantioselective reduction of cyclic 1,3-diketones catalyzed by a recyclable p-chiral phosphinamide organocatalyst
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The P-stereogenic phosphinamides are a structurally novel skeletal class which has not been investigated as chiral organocatalysts. However, chiral cyclic 3-hydroxy ketones are widely used as building blocks in the synthesis of natural products and bioactive compounds. However, general and practical methods for the synthesis of such chiral compounds remain underdeveloped. Herein, we demonstrate that the P-stereogenic phosphinamides are powerful organocatalysts for the desymmetric enantioselective reduction of cyclic 1,3-diketones, providing a useful method for the synthesis of chiral cyclic 3-hydroxy ketones. The protocol displays a broad substrate scope that is amenable to a series of cyclic 2,2-disubstituted five- and six-membered 1,3-diketones. The chiral cyclic 3-hydroxy ketone products bearing an all-carbon chiral quaternary center could be obtained with high enantioselectivities (up to 98% ee) and diastereoselectivities (up to 99:1 dr). Most importantly, the reactions could be practically performed on the gram scale and the catalysts could be reused without compromising the catalytic efficiency. Mechanistic studies revealed that an intermediate formed from P-stereogenic phosphinamide and catecholborane is the real catalytically active species. The results disclosed herein bode well for designing and developing other reactions using P-stereogenic phosphinamides as new organocatalysts.
- Qin, Xu-Long,Li, Ang,Han, Fu-She
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supporting information
p. 2994 - 3002
(2021/03/01)
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- Cine-Silylative Ring-Opening of α-Methyl Azacycles Enabled by the Silylium-Induced C-N Bond Cleavage
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Described herein is the development of a borane-catalyzed cine-silylative ring-opening of α-methyl azacycles. This transformation involves four-step cascade processes: (i) exo-dehydrogenation of alicyclic amine, (ii) hydrosilylation of the resultant enamine, (iii) silylium-induced cis-β-amino elimination to open the ring skeleton, and (iv) hydrosilylation of the terminal olefin. The present borane catalysis also works efficiently for the C-N bond cleavage of acyclic tertiary amines. On the basis of experimental and computational studies, the silicon atom was elucidated to play a pivotal role in the β-amino elimination step.
- Zhang, Jianbo,Chang, Sukbok
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supporting information
p. 12585 - 12590
(2020/08/21)
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- Reduction of Amides to Amines under Mild Conditions via Catalytic Hydrogenation of Amide Acetals and Imidates
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A simple and general protocol was developed for selective conversion of amides into amines. Amides were converted into amide acetals and imido esters by O-alkylation and then hydrogenated without isolation into amines under very mild reaction conditions over standard hydrogenation catalysts. Triethyloxonium tertafluoroborate, methyl trifluoromethanesulfonate, dimethyl sulfate and ethyl chloroformate were validated as alkylating agent. The synthetic utility of this approach was demonstrated by the selective carbonyl reduction of peptide groups. Carbonyl reduction of peptide group proceeds chemoselective without racemization of the neighboring chiral center. (Figure presented.).
- Kadyrov, Renat
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p. 185 - 191
(2018/11/23)
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- Direct Reductive Amination of Carbonyl Compounds Catalyzed by a Moisture Tolerant Tin(IV) Lewis Acid
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Despite the ever-broadening applications of main-group ‘frustrated Lewis pair’ (FLP) chemistry to both new and established reactions, their typical intolerance of water, especially at elevated temperatures (>100 °C), represents a key barrier to their mainstream adoption. Herein we report that FLPs based on the Lewis acid iPr3SnOTf are moisture tolerant in the presence of moderately strong nitrogenous bases, even under high temperature regimes, allowing them to operate as simple and effective catalysts for the reductive amination of organic carbonyls, including for challenging bulky amine and carbonyl substrate partners. (Figure presented.).
- Sapsford, Joshua S.,Scott, Daniel J.,Allcock, Nathan J.,Fuchter, Matthew J.,Tighe, Christopher J.,Ashley, Andrew E.
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supporting information
p. 1066 - 1071
(2018/01/27)
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- Simple Metal-Free Direct Reductive Amination Using Hydrosilatrane to Form Secondary and Tertiary Amines
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This work describes the use of cheap, safe, and easy-to-handle hydrosilatrane as the reductant in direct reductive amination reactions. This efficient method enables a facile, metal-free access to secondary and tertiary amines from a wide range of aldehydes and ketones, with the synthesis of tertiary amines requiring no additives at all. This reaction demonstrates excellent functional group tolerance, chemoselectivity, and scalability. (Figure presented.).
- Varjosaari, Sami E.,Skrypai, Vladislav,Suating, Paolo,Hurley, Joseph J. M.,Lio, Ashley M. De,Gilbert, Thomas M.,Adler, Marc J.
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supporting information
p. 1872 - 1878
(2017/06/09)
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- Expanding the Boundaries of Water-Tolerant Frustrated Lewis Pair Hydrogenation: Enhanced Back Strain in the Lewis Acid Enables the Reductive Amination of Carbonyls
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The development of a boron/nitrogen-centered frustrated Lewis pair (FLP) with remarkably high water tolerance is presented. As systematic steric tuning of the boron-based Lewis acid (LA) component revealed, the enhanced back-strain makes water binding increasingly reversible in the presence of relatively strong base. This advance allows the limits of FLP's hydrogenation to be expanded, as demonstrated by the FLP reductive amination of carbonyls. This metal-free catalytic variant displays a notably broad chemoselectivity and generality.
- Dorkó, éva,Szabó, Márk,Kótai, Bianka,Pápai, Imre,Domján, Attila,Soós, Tibor
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supporting information
p. 9512 - 9516
(2017/08/01)
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- REACTIONS OF STANNYL CATIONS
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The present invention relates to a method of reducing, cleaving and/or coupling at least one C=O, C-O, C=C or C=N bond of a compound, using a reagent comprising a stannyl cation.
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Page/Page column 22; 23
(2018/01/17)
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- The synthesis of sterically hindered amines by a direct reductive amination of ketones
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An atom-economical methodology for the synthesis of sterically hindered tertiary amines was developed, which is based on complementary Rh- and Ru-catalyzed direct reductive amination of ketones with primary and secondary amines using carbon monoxide as a deoxygenating agent.
- Yagafarov, Niyaz Z.,Kolesnikov, Pavel N.,Usanov, Dmitry L.,Novikov, Valentin V.,Nelyubina, Yulia V.,Chusov, Denis
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supporting information
p. 1397 - 1400
(2016/01/25)
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- Reductive amination of carbonyl compounds over silica supported palladium exchanged molybdophosphoric acid catalysts
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Palladium exchanged molybdophosphoric acid supported on silica is reported as a highly effective catalyst for direct reductive amination of carbonyl compounds. The catalysts are characterized by X-ray diffraction and FT-infrared spectroscopy. The characterization results support the existence of Keggin ion of heteropoly molybdate on silica. The catalyst is facile, water tolerable and environmentally benign for reductive amination. A variety of secondary and tertiary amines can be synthesized over this catalyst in excellent yields under mild reaction conditions. A plausible reaction mechanism is proposed for the reductive amination of carbonyl compounds over this catalyst.
- Srivani,Prasad, P. S. Sai,Lingaiah
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experimental part
p. 389 - 396
(2012/06/18)
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- A fast and highly efficient method for the synthesis of tertiary amines in aqueous medium
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A facile and highly efficient method for the synthesis of tertiary amines by the reaction of secondary amines with benzylic bromides and 1,1'-dibromo p/o-xylenes in aqueous dioxane and NaOH is described. The reactions are dually promoted by the base in short time (15 min.) at ambient conditions in aqueous medium.
- Adimurthy, Subbarayappa,Joshi, Girdhar
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experimental part
p. 771 - 775
(2011/01/04)
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- Highly selective N-Alkylation of amines promoted on silica: An efficient and recyclable surface
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N-Alkylation of amines suffers from competing over alkylations. At the same time, use of strong base and other harsh conditions greatly limits providing a practical, generalized and selective procedure. Activated silica gel has been found to promote N-alkylations of amines. Here, we studied N-alkylation of amines with various types of alkyl halides, which finally constitute practical, highly selective and eco-friendly conditions for mono- or bis-alkylated amines at ambient temperature with recyclability of silica.
- Basu, Basudeb,Paul, Susmita,Nanda, Ashis K.
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experimental part
p. 1115 - 1120
(2010/05/02)
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- Direct reductive amination of carbonyl compounds with primary/secondary amines using recyclable water-soluble FeII/EDTA complex as catalyst
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Direct reductive amination of aliphatic, aromatic and heterocyclic carbonyl compounds with primary/secondary amines is reported with water-soluble FeII/EDTA complex as a catalyst using low-pressure molecular hydrogen in a biphasic media. The catalyst is highly selective, recyclable and is an excellent replacement for expensive noble metal catalysts or stoichiometric reducing agents.
- Bhor, Malhari D.,Bhanushali, Mayur J.,Nandurkar, Nitin S.,Bhanage, Bhalchandra M.
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p. 965 - 969
(2008/09/17)
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- Cp*Ir-catalyzed N-alkylation of amines with alcohols. A versatile and atom economical method for the synthesis of amines
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A versatile and highly atom economical catalytic system consisting of [Cp*IrCl2]2/NaHCO3 (Cp*=pentamethylcyclopentadienyl) for the N-alkylation of amines with primary and secondary alcohols as alkylating reagents has been developed. For example, the reaction of equimolar amounts of aniline and benzyl alcohol in the presence of [Cp*IrCl2]2 (1.0 mol % Ir) and NaHCO3 (1.0 mol %) in toluene at 110 °C gives N-benzylaniline in 94% yield. The present catalytic system is applicable to the N-alkylation of both primary and secondary amines, and only harmless water is produced as co-product. A wide variety of secondary and tertiary amines can be synthesized with high atom economy under mild and less-toxic conditions. One-pot sequential N-alkylation leading to tertiary amines bearing three different substituents is also described.
- Fujita, Ken-ichi,Enoki, Youichiro,Yamaguchi, Ryohei
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p. 1943 - 1954
(2008/09/17)
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- In Situ Oxidation-Imine Formation-Reduction Routes from Alcohols to Amines
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(matrix presented) Manganese dioxide is employed as an in situ oxidant for the one-pot conversion of alcohols into imines. In combination with polymer-supported cyanoborohydride (PSCBH), a one-pot oxidation-imine formation-reduction sequence is reported. This procedure enables alcohols to be converted directly into both secondary and tertiary amines.
- Blackburn, Leonie,Taylor, Richard J. K.
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p. 1637 - 1639
(2007/10/03)
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- Gas-phase selective N-alkylation of amines with alcohols over γ- alumina
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Gas-phase conditions were successfully used for fine chemistry, in the N-alkylation of amines with alcohols as alkylating agents and γ-alumina as a catalyst. The method is also suitable for chiral compounds.
- Valot, Frederic,Fache, Fabienne,Jacquot, Roland,Spagnol, Michel,Lemaire, Marc
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p. 3689 - 3592
(2007/10/03)
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