Cyanoborane Adducts Research Articles

Pyridine Adducts of Tricyano‐ and Dicyanoboranes

AbstractCyanoborane adducts of the Lewis acids B(CN)3, BF(CN)2, and BH(CN)2 with pyridine and 4‐cyanopyridine have been obtained in high yields. The syntheses were accomplished by oxidation of the readily available potassium salts of the cyano(hydrido)borate anions [BH(CN)3]− (MHB), [BFH(CN)2]− (FHB), and [BH2(CN)2]− (DHB) with bromine in the presence of the respective pyridine derivative C5H5N or 4‐CN‐C5H4N as starting material. All six cyanoborane adducts have been characterized by NMR and vibrational spectroscopy, elemental analysis, and single‐crystal X‐ray diffraction. The reduction of the cyanoborane adducts has been investigated by cyclic voltammetry and the Lewis acidity of the different cyanoboranes has been assessed using the Gutmann‐Beckett method. Selected experimental data and trends are compared to theoretical ones, for example fluoride ion affinities (FIAs).

Crystallographic Insights into the Synthesis and Magnetic Properties of Oxoverdazyl Radicals Functionalized by Benzoic Acid

The synthesis and crystallization of two verdazyl radicals, 1,5‐dimethyl‐3‐(4′‐carboxyphenyl)‐6‐oxoverdazyl HIMe and 1,5‐diisopropyl‐3‐(4′‐carboxyphenyl)‐6‐oxoverdazyl HIiPr, are described. The electrochemical studies reveal that the oxidation of the two radicals is reversible, whereas their reduction is irreversible. The EPR spectrum of both radicals essentially exhibits a nine‐line pattern related to the mean hyperfine interaction of the unpaired electron with the nitrogen atoms of the verdazyl cycle. The single‐crystal X‐ray diffraction of the intermediates towards HIiPr allows a fine description of the cyanoborane adduct, which is the key intermediate of this synthesis. The verdazyl radicals themselves are obtained as single crystals. In the case of HIiPr, depending on the solvent, two polymorphs are crystallized. The structure resolution reveals that, in the solid state, the organization of the verdazyl radicals is governed by both H‐bonding and π–π interactions and is reminiscent of the H‐bonded structures that can be present in solution. Within the 1D π stacks observed in the three compounds, the verdazyl–verdazyl distance varies from 4.88 Å in HIMe to 7.90 Å in HaIiPr. This modulation of the distance strongly influences the antiferromagnetic intermolecular exchange interaction between π‐stacked radicals, which goes from J = –90 cm–1 (H = –JΣSiSi+1) for HIMe to –12.96(3) cm–1 for HbIiPr and –0.92 cm–1 for HaIiPr.

ChemInform Abstract: Sodium Cyanoborohydride Reduction of (Benzyloxycarbonyl)- and (tert- Butoxycarbonyl)hydrazones.

(Benzyloxycarbonyl)- and (tert-butoxycarbonyl)hydrazones are easily reduced by sodium cyanoborohydride in acidic medium. The method is an alternative to catalytic hydrogenation and allows ready access to both N-benzyloxycarbonyl and N-tert-butoxycarbonyl protected N'-alkyl- and N'-arylmethylhydrazines. The products can be isolated as the solid, stable cyanoborane adducts

Synthesis, characterization and crystal structures of boron-containing intermediates in the reductive amination of ferrocenecarboxaldehyde to a bis(ferrocenylmethyl) amine

Reaction of ferrocenecarboxaldehyde with aqueous methylamine leads to [(methylimino)methyl]ferrocene, which is reduced to N-(ferrocenylmethyl)- N-methylamine by NaBH 4. This amine reacts with ferrocenecarboxaldehyde and NaCNBH 3 to give the tertiary ammonium salt, di( N-(ferrocenylmethyl))- N-methylammonium cyanoborohydride. Hydrolysis of the NaCNBH 3 reaction mixture produces the free amine, di( N-(ferrocenylmethyl))- N-methylamine. Thermolysis of di( N-(ferrocenylmethyl))- N-methylammonium cyanoborohydride in refluxing tetrahydrofuran converts it to the cyanoborane adduct, di( N-ferrocenylmethyl)- N-methylamine–cyanoborane, with elimination of H 2. The new compounds are fully characterized by using spectroscopic and physical methods, including X-ray crystal structure determinations of di( N-(ferrocenylmethyl))- N-methylammonium cyanoborohydride, di( N-(ferrocenylmethyl))- N-methylamine, and di( N-(ferrocenylmethyl))- N-methylamine–cyanoborane.

In vitro antimycobacterial activities of 2'-monosubstituted isonicotinohydrazides and their cyanoborane adducts.

As a result of our search for new isoniazid derivatives with extended spectra of activity, we evaluated the in vitro antimycobacterial activities of isonicotinohydrazides (compounds 2) and their cyanoborane adducts (compounds 3), both obtained by the reaction of isonicotinoylhydrazones (compounds 1) with sodium cyanoborohydride. Most of the tested compounds displayed moderate to high activity against Mycobacterium tuberculosis H37Rv, with MICs ranging from 0.2 to 12.5 microg/ml. In particular, some hydrazides showed activity similar to that of rifampin (MIC = 0.2 microg/ml) and rather low cytotoxicity, so that they were generally shown to possess high safety indices. In contrast, the coordination to a cyanoborane (BH(2)CN) group (compounds 3) in general brought about a decrease in antimycobacterial activity, while cytotoxicity increased. Interestingly, selected compounds 1 to 3, mostly hydrazides (compounds 2), were effective in killing M. tuberculosis growing within macrophages at concentrations in culture medium which were much lower than the corresponding MICs. These compounds also displayed good activity against drug-resistant M. tuberculosis strains.

Synthesis and Cytotoxicity of Cyanoborane Adducts ofN6‐Benzoyladenine and 6‐Triphenylphosphonylpurine

-Benzoyladenine-cyanoborane (2), and 6-triphenylphosphonylpurine-cyanoborane (3) were selected for investigation of cytotoxicity in murine and human tumor cell lines, effects on human HL-60 leukemic metabolism and DNA strand scission to determine the feasibility of these compounds as clinical antineoplastic agents. Compounds 2 and 3 both showed effective cytotoxicity based on ED50 values less than 4 μg/ml for L1210, P388, HL-60, Tmolt3, HUT-78, HeLa-S3 uterine, ileum HCT-8, and liver Hepe-2. Compound 2 had activity against ovary 1-A9, while compound 3 was only active against prostate PL and glioma UM. Neither compound was active against the growth of lung 549, breast MCF-7, osteosarcoma HSO, melanoma SK2, KB nasopharynx, and THP-1 acute monocytic leukemia. In mode of action studies in human leukemia HL-60 cells, both compounds demonstrated inhibition of DNA and protein syntheses after 60 min at 100 μM. These compounds inhibited RNA synthesis to a lesser extent. The utilization of the DNA template was suppressed by the compounds as determined by inhibition of the activities of DNA polymerase α, m-RNA polymerase, r-RNA polymerase and t-RNA polymerase, which would cause adequate inhibition of the synthesis of both DNA and RNA. Both compounds markedly inhibited dihydrofolate reductase activity, especially in compound 2. The compounds appeared to have caused cross-linking of the DNA strands after 24 hr at 100 μM in HL-60 cells, which was consistent with the observed increased in ct-DNA viscosity after 24 hr at 100 μM. The compounds had no inhibitory effects on DNA topoisomerase I and II activities or DNA-protein linked breaks. Neither compound interacted with the DNA molecule itself through alkylation of the nucleotide bases nor caused DNA interculation between base pairs. Overall, these antineoplastic agents caused reduction of DNA and protein replication, which would lead to killing of cancer cells.

2'-[1-(4-Fluorophenyl)ethyl]isonicotino-κN-hydrazide–Cyanoborane

The title compound, C 15 H 16 BFN 4 O, is a cyanoborane adduct showing a butterfly-like conformation, with the fluorophenyl moiety disordered.

Disposition and Distribution of the Cytidine Cyanoborane Adduct, [2-14C]-2′-Deoxycytidine-3N-Cyanoborane, in CF1 Mice

2′-Deoxycytidine-3N-cyanoborane (dC-BH2CN) had been found to possess cytotoxic, hypo-lipidaemic, and anti-inflammatory activity; its disposition in mice was investigated in this report. The half-life of dC-BH2CN was found to be 0.3 hours and 2′-deoxycytidine was identified as one metabolite. A second elimination rate-limited metabolite was also formed, but was not identified. dC-BH2CN was taken up in vitro in human BG-9 fibroblasts, rat red blood cells, and murine Tmolt3 cells, and in vivo in Ehrlich ascites carcinoma cells. In the Ehrlich ascites tumour, concentrations of dC-BH2CN were 4- to 8-fold higher than liver and plasma from 2 to 24 hours after administration.

Hypolipidaemic activity in rodents of boron analogs of phosphonoacetates and cyanoborane adducts of dialkyl aminomethylphosphonates

Boron analogues of phosphonoacetates proved to be potent hypolipidaemic agents in rodents, lowering both serum cholesterol and triglyceride levels. (C2H5O)3PBH2COOCH3 proved to be the most effective agent in mice, lowering serum cholesterol 46% and serum triglycerides 54% after 16 days. (C2H5O)3PBH2COOH and Na+H+(C2H5O)2(-O)PBH2COO- caused greater than a 40% reduction in lipids. The cyanoborane adducts of aminomethylphosphonates were generally less effective; (C6H5O)2P(O)CH2NH2BH2CN was the most effective, lowering serum cholesterol 32% and serum triglycerides 43% after 16 days. The phosphonoacetates appeared to lower lipid concentrations by several mechanisms. First, they lowered the de novo synthesis of cholesterol and triglycerides in the liver. Second, they accelerated the excretion of lipids into the bile and faeces. Thirdly, they modulated LDL and HDL-cholesterol contents in a manner which suggests they reduced the deposition of lipids in peripheral tissues, and accelerated the movement of cholesterol from tissues (e.g. plaques) to the liver for excretion into the bile.

Kinetics and mechanism of hydrolysis of some amine–cyanoborances in acid perchlorate media

In acid media ([H+]= 0.02–0.2 mol dm–3), isoproplyamine– and diisopropylamine–cyanoborane are hydrolysed completely to boric acid, hydrogen, hydrogen cyanide and the salt of the corresponding amine. The reaction occurs in steps, viz. (1) rapid loss of CN– as HCN and one H– as H2, (2) rate-determining B–H bond breaking and loss of the second H– as H2 and (3) very slow B–N bond breaking. The B–H bond breaking is rate determining also in the acid hydrolysis of BH3(CN)– ion. Step (2) is first order both in [substrate] and [H+]. Rate constant and activation parameters for step(2) have been determined. Cyanoborane adducts of tertiary amines, Me3N and Pri3N, Do not hydrolyse and it appears that the steric bullk of the non-leaving amine group has the dominant effect on the rate of hydrolysis of the adducts.

Sodium Cyanoborohydride Reduction of (Benzyloxycarbonyl)- and (tert-Butoxycarbonyl)hydrazones

(Benzyloxycarbonyl)- and (tert-butoxycarbonyl)hydrazones are easily reduced by sodium cyanoborohydride in acidic medium. The method is an alternative to catalytic hydrogenation and allows ready access to both N-benzyloxycarbonyl and N-tert-butoxycarbonyl protected N′ -alkyl- and N′-arylmethylhydrazines. The products can be isolated as the solid, stable cyanoborane adducts.

ChemInform Abstract: Synthesis and Characterization of Monosubstituted Borane Adducts of Diethyl ((Dimethylamino)methyl)phosphonate.

AbstractThe borane adducts (III), (IV), (V), (VI), and (VII) are synthesized as shown starting with the cyanoborane adduct (I).

Synthesis and characterization of pseudohaloborane adducts of some heteroaromatic N-bases

Six cyanoborane adducts of the heteroaromatic amines, 2-amino-, 3-amino-, 4-amino-, 2-amino-4- methyl-, 4-cyano- and 4-ethylpyridines, and four isothiocyanatoborane adducts of the heteroaromatic amines, 3-methyl-, 4-methyl-, 4-ethyl- and 4-amino- pyridines have been prepared. These have been characterized by elemental analyses and by infrared and 1H and 11B NMR spectral study.

ChemInform Abstract: Boron‐Containing Nucleic Acids: Synthesis of Cyanoborane Adducts of 2′‐Deoxynucleosides.

AbstractFour novel boronated nucleosides (III) and (IV) are prepared.

Studies on the Reactivity of Dicyanodihydroborate with Some Lewis Base Hydrochlorides

Abstract The reactions of sodium dicyanodihydroborate with various Lewis base hydrochlorides produce mainly the metathesis reaction products in contrast to those of sodium cyanotrihydroborate, which produces cyanoborane adducts. This has been established with the help of IR, 1H and 11B NMR data.

Structure of 4-(dimethylamino)pyridine cyanoborane adduct

C7H~oNa.BHaCN, Mr = 161.0, monoclinic, 12/a, a = 13.773 (4), b = 9.635 (3), c = 14.430 (3) ~, fl = 99.67 (2) °, V = 1888 (2) A 3, Z = 8, Dx = 1-13 gcm -3, a(Mo Ka) =0.71073/~, /z = 0.7 cm -l, F(000)=688, 294K. Final R=0.047 for 809 observed reflections. The non-hydrogen atoms in the (dimethylamino)pyridine residue are essentially co- planar; the nitrogen atom (N7) of the Me2N group has sp 2 hybridization. There is substantial localized double bonding involving N7 and the pyridine ring. The N 1--BH2CN section of the molecule has N 1--B 1.574(4), B--C 1-573(5), C--N 1-130 (4) A, N1--B---C 109.4 (3), B--C--N 178-2 (3) °. Introduction. There is considerable current interest in amine adducts of cyanoboranes as precursors to boron-containing analogues of amino acids (Spielvogel, Ahmed, Silvey, Wisian-Neilson &

Boron-containing nucleic acids. Synthesis of cyanoborane adducts of 2'-deoxynucleosides

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTBoron-containing nucleic acids. Synthesis of cyanoborane adducts of 2'-deoxynucleosidesAnup Sood, Barbara Ramsay Shaw, and Bernard F. SpielvogelCite this: J. Am. Chem. Soc. 1989, 111, 26, 9234–9235Publication Date (Print):December 1, 1989Publication History Published online1 May 2002Published inissue 1 December 1989https://doi.org/10.1021/ja00208a019RIGHTS & PERMISSIONSArticle Views257Altmetric-Citations50LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (289 KB) Get e-Alerts Get e-Alerts

ChemInform Abstract: Synthesis and Characterization of Cyanoborane Adducts of Dialkyl ((Dialkylamino)methyl)phosphonates.

AbstractThree methods for preparation of the cyanoborane adducts (III) are compared from which that shown in the scheme is the method of choice due to the absence of decomposition products, good yields, and ease of purification.

Synthesis and characterization of cyanoborane adducts of dialkyl ((dialkylamino)methyl)phosphonates

Les composes d'addition cyanoborane-dialkyl dialkylaminomethyl phosphonates sont prepares a partir de (dialkyl dialkylaminomethyl) phosphonates avec un cyanotrihydroborate de sodium via un oligomere cyanoborane

ChemInform Abstract: CHLOROFORMATE ESTER‐INDUCED REDUCTIVE 1,2‐BOND CLEAVAGE OF SOME 1,2,3,4‐TETRAHYDRO‐β‐CARBOLINE DERIVATIVES

AbstractBei der reduktiven Spaltung des Tetrahydrocarbolins (I) entsteht zusätzlich zum Urethan (II) das Addukt (III).