- 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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- The role of ammonia in promoting ammonia borane synthesis
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Ammonia promotes the synthesis of pure ammonia borane (AB) in excellent yields from sodium borohydride and ammonium sulfate in tetrahydrofuran under ambient conditions. An examination of the influence of added ammonia reveals that it is incorporated into the product AB, contrary to its perceived function as a catalyst or a co-solvent. Mechanistic studies point to a nucleophilic attack by ammonia on ammonium borohydride with concurrent dehydrogenation to yield AB.
- Ramachandran, P. Veeraraghavan,Kulkarni, Ameya S.
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p. 16433 - 16440
(2016/10/31)
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- Electrophilic C-H borylation and related reactions of B-H boron cations
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Catalytic procedures are described for the amine-directed borylation of aliphatic and aromatic tertiary amine-boranes. Sequential double borylation is observed in cases where two or more C-H bonds are available that allow 5-center or 6-center intramolecular borylation. The HNTf2-catalyzed borylation of benzylamine-boranes provides a practical means for the synthesis of ortho-substituted arylboronic acid derivatives, suitable for Suzuki-Miyaura cross-coupling applications.
- Prokofjevs, Aleksandrs,Jermaks, Janis,Borovika, Alina,Kampf, Jeff W.,Vedejs, Edwin
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p. 6701 - 6711
(2014/01/06)
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- One-pot synthesis of ammonia-borane and trialkylamine-boranes from trimethyl borate
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A one-pot procedure for the preparation of ammonia borane from trimethyl borate in 90% yield and >99% purity has been reported. This methodology has been modified to prepare a series of trialkylamine-boranes in 70-82% yields from trimethyl borate and lithium hydride/aluminum chloride in the presence of the corresponding trialkylamine.
- Veeraraghavan Ramachandran,Raju, Bhimapaka C.,Gagare, Pravin D.
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supporting information
p. 6119 - 6121
(2013/02/25)
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