- Efficient reductions of dimethylhydrazones using preformed primary amine boranes
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A convenient method for the reduction of N,N-dimethylhydrazones using amine borane complexes generated in situ is described. It was found that primary amine borane complexes performed exceedingly well at reducing N,N-dimethylhydrazones in as little as 1.1 equivalents, furnishing the corresponding air-sensitive hydrazine products in excellent yields.
- Frabitore, Christian,Lépeule, Jérome,Livinghouse, Tom,Robinson, William C.,Towey, Bradley
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supporting information
(2021/12/21)
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- Activation of sodium borohydride via carbonyl reduction for the synthesis of amine- And phosphine-boranes
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A highly versatile synthesis of amine-boranes via carbonyl reduction by sodium borohydride is described. Unlike the prior bicarbonate-mediated protocol, which proceeds via a salt metathesis reaction, the carbon dioxide-mediated synthesis proceeds via reduction to a monoformatoborohydride intermediate. This has been verified by spectroscopic analysis, and by using aldehydes and ketones as the carbonyl source for the activation of sodium borohydride. This process has been used to produce borane complexes with 1°-, 2°-, and 3°-amines, including those with borane reactive functionalities, heteroarylamines, and a series of phosphines.
- Hamann, Henry J.,Lin, Randy,Veeraraghavan Ramachandran, P.
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supporting information
p. 16770 - 16774
(2021/12/08)
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- Visible light-mediated synthesis of amides from carboxylic acids and amine-boranes
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Here, a photocatalytic deoxygenative amidation protocol using readily available amine-boranes and carboxylic acids is described. This approach features mild conditions, moderate-to-good yields, easy scale-up, and up to 62 examples of functionalized amides with diverse substituents. The synthetic robustness of this method was also demonstrated by its application in the late-stage functionalization of several pharmaceutical molecules.
- Chen, Xuenian,Kang, Jia-Xin,Ma, Yan-Na,Miao, Yu-Qi
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supporting information
p. 3595 - 3599
(2021/06/06)
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- Amine-boranes as Dual-Purpose Reagents for Direct Amidation of Carboxylic Acids
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Amine-boranes serve as dual-purpose reagents for direct amidation, activating aliphatic and aromatic carboxylic acids and, subsequently, delivering amines to provide the corresponding amides in up to 99% yields. Delivery of gaseous or low-boiling amines as their borane complexes provides a major advantage over existing methodologies. Utilizing amine-boranes containing borane incompatible functionalities allows for the preparation of functionalized amides. An intermolecular mechanism proceeding through a triacyloxyborane-amine complex is proposed.
- Choudhary, Shivani,Hamann, Henry J.,Ramachandran, P. Veeraraghavan
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supporting information
(2020/11/13)
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- Method for the production of amine borane complex (by machine translation)
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The invention belongs to the technical field of material preparation, in particular relates to a method for the production of amine borane complex. This invention adopts the borane amine of the direct reaction of an inert gas stream, by regulating the ratio of the two, the need for further post-processing, to make the final product amine complex and offer. In the reaction process such impurity is introduced into the salt-free, does not use an organic solvent; the use of borohydride such as the reagent to produce the borane, for now the current system, can avoid direct operation of toxic gas borane. The method of the invention is simple in operation, the product has high purity, low cost, and can be continuous large-scale production. At the same time, the method and other way to produce the amine borane complex equipment compatible, production equipment by simple method can be used to adjust the production. (by machine translation)
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Paragraph 0037; 0038
(2017/12/05)
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- Amine-boranes bearing borane-incompatible functionalities: Application to selective amine protection and surface functionalization
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The first general open-flask synthesis of amine-boranes with inexpensive and readily available reagents, such as sodium borohydride, sodium bicarbonate, water, and the desired amines is described. Even amines bearing borane-reactive functionalities, such as alkene, alkyne, hydroxyl, thiol, ester, amide, nitrile, and nitro are well tolerated. Some of these novel amine-boranes represent stable molecules containing potentially incompatible electrophilic and nucleophilic centers in proximity. This convenient scalable synthesis provides a novel class of organic ligands for surface functionalization, as demonstrated by the formation of self-assembled layers of thiol- and alkoxysilane-bearing amine-boranes on gold and silica surfaces, respectively.
- Veeraraghavan Ramachandran,Kulkarni, Ameya S.,Zhao, Yan,Mei, Jianguo
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supporting information
p. 11885 - 11888
(2016/10/09)
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- Open-Flask Synthesis of Amine-Boranes via Tandem Amine-Ammonium Salt Equilibration-Metathesis
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An amine-ammonium salt equilibration-metathesis sequence provides high-purity amine-boranes in excellent yields from sodium borohydride in refluxing reagent-grade tetrahydrofuran in an open flask.
- Ramachandran, P. Veeraraghavan,Kulkarni, Ameya S.
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supporting information
p. 5618 - 5620
(2015/06/25)
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- Dehydrocoupling reactions of borane-secondary and -primary amine adducts catalyzed by group-6 carbonyl complexes: Formation of aminoboranes and borazines
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Photoirradiation of a solution of BH3·NHR2 (1a: R = Me, 1b: R = 1/2C4H8, 1c: R = 1/2C 5H10, 1f: R = Et) containing a catalytic amount of a group-6 metal carbonyl complex, [M(CO)6] (M = Cr, Mo, W), led to dehydrogenative B-N covalent bond formation to produce aminoborane dimers, [BH2NR2]2 (2a-c, f), in high yield. During these reactions a borane σ complex, [M(CO)5(η1- BH3·NHR2)] (3), was detected by NMR spectroscopy. Similar catalytic dehydrogenation of bulkier amineboranes, BH 3·NHiPr2 (1d) and BH3· NHCy2 (1e, Cy = cyclo-C6H11), afforded monomeric products BH2=NR2 (4d, e). The reaction mechanism of the dehydrocoupling was investigated by DFT calculations. On the basis of the computational study, we propose that the catalytic dehydrogenation reactions proceed via an intramolecular pathway and that the active catalyst is [Cr(CO)4]. The reaction follows a stepwise mechanism involving NH and BH activation. Dehydrocoupling of borane-primary amine adducts BH 3·NH2R (1g: R = Me, 1h: R = Et, 1i: R = tBu) gave borazine derivatives [BHNR]3 (5g-i).
- Kawano, Yasuro,Uruichi, Mikio,Shimoi, Mamoru,Taki, Seitaro,Kawaguchi, Takayuki,Kakizawa, Taeko,Ogino, Hiroshi
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p. 14946 - 14957
(2010/01/16)
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- Crown-ether-catalysed synthesis of amine borane and amine trideuterioborane adducts from NaBH4-NaBD4 in ether
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Amine borane and amine trideuterioborane adducts have been obtained in good yield by the crown-ether-catalysed reaction of R3N*HCl with NaBH4 and NaBD4 in ether.The absence of isotopic exchange in the reaction with NaBD4 is demonstrated by IR and 11B and
- Kampel, V.,Warshawsky, A.
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- 13C nuclear magnetic resonance studies of aromatic amine-borane adducts
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13C NMR measurements are reported for 22 aromatic amine-borane, 7 aliphatic amine-borane, and 3 aliphatic amine-trimethylborane adducts.Additivity of the substituent effects on the δ 13C values of the aromatic carbon atoms is observed.The δ 13C values are compared with those of the arylamines of arylammonium salts and of corresponding alkyl-substituted benzenes.The δ 13C values for the borane adducts, ammonium salts and hydrocarbons exhibit the same trends.However, in the borane adducts similar to the ammonium salts, part of the shielding of the ortho-carbon atoms is attributed to electric field effects which are much less pronounced in the hydrocarbon analogues.The comparison of δ 13C values of aliphatic amine-borane adducts with those of corresponding hydrocarbons indicates the importance of steric effects.
- Paz-Sandoval, M. A.,Camacho, C.,Contreras, R.,Wrackmeyer, B.
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p. 1331 - 1336
(2007/10/02)
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- Water‐promoted, open‐flask synthesis of amine‐boranes: 2‐methylpyridine‐borane (2‐picoline‐borane)
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A procedure yielding 2‐methylpyridine‐borane as a white solid is presented. Sodium borohydride and powdered sodium bicarbonate are added into a single‐necked, air‐dried round‐bottomed flask with a Teflon‐coated, egg‐shaped magnetic stir bar. A discussion on amine‐boranes, reductive amination with aldehyde bisulfites and carbohydrates, and metathesis of metal borohydrides with alkylammonium salts concludes the chapter.
- Kulkarni, Ameya S.,Ramachandran, P. Veeraraghavan
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