1592-38-7Relevant articles and documents
Tritium and deuterium labelling studies of alkali metal borohydrides and their application to simple reductions
Than,Morimoto,Andres,Williams
, p. 693 - 711 (1996)
Simple and facile syntheses of highly deuterated and tritiated LiBH4, NaBH4 and KBH4 were achieved by hydrogen Isotope exchange with deuterium or tritium gas at elevated temperatures. The exchange products were characterized by boron, proton and deuterium or tritium NMR spectroscopy. The extent of isotope (2H or 3H) incorporation was calculated from the patterns of 11B NMR spectra. Several samples of tritiated NaBH4 were treated with BF3-Et2O to produce tritiated borane-THF complex, which is an electrophilic reducing agent. The utility of both the borohydride reagents and borane-THF complex in labelling reactions was confirmed by exemplary reductions leading to specifically labelled products. The extent and orientation of labelling in the reduction products was assessed by a combination of radio-HPLC analysis, 1H, 2H or 3H NMR and mass spectrometry.
Discovery of inhibitors and substrates of brassinin hydrolase: Probing selectivity with dithiocarbamate bioisosteres
Pedras, M. Soledade C.,Minic, Zoran,Hossain, Sajjad
, p. 225 - 233 (2012)
Brassinin hydrolase (BHAb), an inducible enzyme produced by the plant pathogen Alternaria brassicicola under stress conditions, catalyzes the hydrolysis of the methyl dithiocarbamate group of the phytoalexin brassinin, to indolyl-3-methanamine, methane thiol and carbonyl sulfide. Thirty four substrate inspired compounds, bioisosteres of brassinin and a range of related compounds, were evaluated as potential substrates and inhibitors of BHAb for the first time. While six compounds containing thiocarbamate, carbamate and carbonate groups displayed inhibitory activity against BHAb, only two were found to be substrates (thionecarbamate and dithiocarbamate). Methyl naphthalen-1-yl-methyl carbamate, the most potent inhibitor of the six, and methyl N′-(1-methyl- 3-indolylmethyl)carbamate inhibited BHAb through a reversible noncompetitive mechanism (Ki = 89 ± 9 and 695 ± 60 μM, respectively). Importantly, these carbamate inhibitors were resistant to degradation by A. brassicicola. Carbonates were also inhibitory of BHAb, but a quick degradation by A. brassicicola makes their potential use as crop protectants less likely. Overall, these results indicate that indolyl and naphthalenyl carbamates are excellent lead structures to design new paldoxins that could inhibit the detoxification of brassinin by A. brassicicola.
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White,E.H. et al.
, p. 8107 - 8113 (1973)
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Ouchi et al.
, p. 918,919, 920 (1975)
Application of bis(phosphinite) pincer nickel complexes to the catalytic hydrosilylation of aldehydes
Chang, Jiarui,Fang, Fei,Tu, Chenhao,Zhang, Jie,Ma, Nana,Chen, Xuenian
, (2021)
A series of bis(phosphinite) (POCOP) pincer ligated nickel complexes, [2,6-(tBu2PO)2C6H3]NiX (X = SH, 1; SCH2Ph, 2; SPh, 3; NCS, 4; N3, 5), were used to catalyse the hydrosilylation of aldehydes. It was found that both complexes 1 and 2 are active in catalysing the hydrosilylation of aldehydes with phenylsilane and complex 1 is comparatively more active. The expected alcohols were isolated in good to excellent yields after basic hydrolysis of the resultant hydrosilylation products. However, no reaction was observed when complex 3 or 4 or 5 was used as the catalyst. The results are consistent with complexes 1 and 2 serving as catalyst precursors, which generate the corresponding nickel hydride complex [2,6-(tBu2PO)2C6H3]NiH in situ, and the nickel hydride complex is the active species that catalyses this hydrosilylation process. The in situ generation of the nickel hydride species was supported by both experimental results and DFT calculation.
One-Shot Double Amination of Sondheimer-Wong Diynes: Synthesis of Photoluminescent Dinaphthopentalenes
Xu, Feng,Peng, Lifen,Shinohara, Kenta,Nishida, Takanori,Wakamatsu, Kan,Uejima, Motoyuki,Sato, Tohru,Tanaka, Kazuyoshi,Machida, Norihiko,Akashi, Haruo,Orita, Akihiro,Otera, Junzo
, p. 3014 - 3017 (2015)
Photoluminescent diamino-substituted dinaphthopentalenes were synthesized successfully by the treatment of in situ prepared dinaphthocyclooctadiyne with lithium amide. This reaction involves a series of transformations including the nucleophilic addition
Cytochrome P450BM-3 reduces aldehydes to alcohols through a direct hydride transfer
Kaspera, Rüdiger,Sahele, Tariku,Lakatos, Kyle,Totah, Rheem A.
, p. 464 - 468 (2012)
Cytochrome P450BM-3 catalyzed the reduction of lipophilic aldehydes to alcohols efficiently. A kcat of ～25min-1 was obtained for the reduction of methoxy benzaldehyde with wild type P450BM-3 protein which was higher than in the isolated reductase domain (BMR) alone and increased in specific P450-domain variants. The reduction was caused by a direct hydride transfer from preferentially R-NADP2H to the carbonyl moiety of the substrate. Weak substrate-P450-binding of the aldehyde, turnover with the reductase domain alone, a deuterium incorporation in the product from NADP2H but not D2O, and no inhibition by imidazole suggests the reductase domain of P450BM-3 as the potential catalytic site. However, increased aldehyde reduction by P450 domain variants (P450BM-3 F87A T268A) may involve allosteric or redox mechanistic interactions between heme and reductase domains. This is a novel reduction of aldehydes by P450BM-3 involving a direct hydride transfer and could have implications for the metabolism of endogenous substrates or xenobiotics.
The tert-butyl chloride-lithium naphthalene radical anion and tert-butyllithium-naphthalene systems. Mechanism of metallation
Screttas, Constantinos G.,Micha-Screttas, Maria,Steele, Barry R.
, p. 149 - 163 (1997)
A mechanism of lithiation of aromatics has been inferred from a comparative study of the systems tert-butyl chloride-lithium naphthalene radical anion and tert-butyllithium-naphthalene. Both systems give tert-butyldihydronaphthyllithiums, naphthyllithiums and tert-butylnaphthalenes. Although tert-butyllithium is a reaction product in the former system, it has been shown not to be involved in the formation of the products. In the system tert-butyllithium-naphthalene the distribution of products is markedly dependent upon the strength of the catalyzing Lewis base. Weak Lewis bases favor formation of tert-butylnaphthalene (mainly the 2-isomer) as well as tert-butyldihydronaphthyllithiums, whereas strong Lewis bases favor metallation. Mechanisms are proposed which postulate the involvement of a tert-butyl radical-naphthalene donor-acceptor complex in the fundamental elementary reaction.
Platinum thiolate complexes supported by PBP and POCOP pincer ligands as efficient catalysts for the hydrosilylation of carbonyl compounds
Chang, Jiarui,Chen, Xuenian,Xue, Man-Man,Zhang, Jie
supporting information, p. 2304 - 2312 (2022/02/21)
Diphosphino-boryl-based PBP pincer platinum thiolate complexes, [Pt(SR){B(NCH2PtBu2)2-1,2-C6H4}] (R = H, 1a; Ph, 1b), and benzene-based bisphosphinite POCOP pincer platinum thiolate complexes, [Pt(SR)(tBu2PO)2-1,3-C6H3] (R = H, 2a; Ph, 2b), were prepared
Deoxygenative hydroboration of primary, secondary, and tertiary amides: Catalyst-free synthesis of various substituted amines
Yi, Jaeeun,Kim, Hyun Tae,Jaladi, Ashok Kumar,An, Duk Keun
, p. 129 - 132 (2021/11/17)
Transformation of relatively less reactive functional groups under catalyst-free conditions is an interesting aspect and requires a typical protocol. Herein, we report the synthesis of various primary, secondary, and tertiary amines through hydroboration of amides using pinacolborane under catalyst-free and solvent-free conditions. The deoxygenative hydroboration of primary and secondary amides proceeded with excellent conversions. The comparatively less reactive tertiary amides were also converted to the corresponding N,N-diamines in moderate yields under catalyst-free conditions, although alcohols were obtained as a minor product.
