Incorporation of 5-substituted uracil derivatives into nucleic acids—I: Synthesis of some 5-substituted uracils

5-(1-Hydroxyethyl)uracil, prepared by the reduction of 5-acetyluracilwith sodium borohydride, has been dehydrated with formic acid to give 5-vinyluracil and a dimer of 5-vinyluracil. trans 1,3-bis (uracil-5-yl)but-1-ene. These compounds have also been prepared with a tritium label in an identified position and with a high specific activity such that their incorporation into nucleic acids can be monitored.     

General and practical conversion of aldehydes to homologated carboxylic acids

The reaction of aldehydes with trichloromethide followed by sodium borohydride or sodium phenylseleno(triethyl)borate under basic conditions affords homologated carboxylic acids in high yields. This operationally simple procedure provides a practical, efficient alternative to other homologation protocols. The approach is compatible with sensitive aldehydes including enals and enolizable aldehydes. It also offers convenient access to alpha-monodeuterated carboxylic acids.     

Studies on epoxides—VI : Opening reactions of α-substituted epoxysteroids

Treatment of 1,2-epoxy-3-ketosteroids with tosylhydrazine and sodium borohydride in methanol lead to mixtures consisting of (i) ring A seco-acetylenic alcohols, (ii) methoxyhydrins formed by opening of the epoxide ring following the carbonyl reduction, and (iii) an epoxy-3,3-di- methylketal. For the corresponding 4-methylene derivative, the ring A fragmentation product was found to be the conjugated en-yne 8a. Reduction of these epoxyketones with sodium borohydride alone affords mixtures of cis- and trans epoxyalcohols; the cis derivatives were unaffected by heating with sodium borohydride in methanol, whereas the trans were converted into the corresponding diaxial methoxyhydrins.     

An extremely simple, convenient and mild one-pot reduction of carboxylic acids to alcohols using 3,4,5-trifluorophenylboronic acid and sodium borohydride

Acyloxyboron intermediates formed in situ from carboxylic acids and 3,4,5-trifluorophenylboronic acids react with sodium borohydride in THF to give alcohols in good to high yields.     

Investigation of the selective reduction of isatin derivatives. Synthesis of α-hydroxyacetophenone derivatives and ethyl spiro-3,3-(ethylenedioxy)-2-hydroxyindoline carboxylates

The product from the reduction of ethyl spiro-3,3-(ethylenedioxy)-2-oxindole carboxylates (1) using borohydride salts has been found to be dependant upon both solvent and metal ion. With polar solvents and lithium bromide/sodium borohydride, spiro-3,3-(ethylenedioxy)-2-hydroxyindole carboxylates (2) are obtained in high yields whilst [2-(2-hydroxymethyl-[1,3]dioxolan-2-yl)-phenyl]-carbamic acid ethyl esters (3) are obtained using sodium borohydride in less polar solvents.     

Solvent-free reduction of aldehydes and ketones using solid acid-activated sodium borohydride

A simple and convenient procedure for the reduction of aldehydes and ketones with sodium borohydride activated by solid acids such as boric acid, benzoic acid, and p-toluenesulfonic acid monohydrate under solvent-free conditions is described.     

Studies on pyrrolidones. An improved synthesis of N‐arylmethyl pyroglutamic acids

Low solubility of the aromatic aldehyde in a water/ethanol medium can prevent the sodium borohydride reductive alkylation of the sodium salt of glutamic acid. In that case, the reductive alkylation can be realized in methanol by using a triethylammonium salt. The uses of 2 molar equivalent of triethylammonium salt of glutamic acid for one molar equivalent of aldehyde strongly raise the yields. Cyclization of the N‐substituted glutamic acids obtained gives then N‐arylmethyl pyroglutamic acids in good yields.     

A novel approach to isoindolo[2,1-a]indol-6-ones

A convenient route to isoindolo[2,1-a]indol-6-ones has been developed starting from the appropriate 2-(N-phthaloyl)benzoic acids. Formation of the acid chlorides with thionyl chloride followed by heating with triethyl phosphite in a suitable solvent resulted in a multistep reaction giving tetracyclic β-ketophosphonates that on reduction with sodium borohydride gave the required indolones in good overall yields. Analogous β-ketophosphonates were also prepared starting with N,N-(1,8-naphthaloyl)-2-aminobenzoic acid and 2-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)benzoic acids although of these only the naphthaloyl product could be reduced with sodium borohydride without cleaving the amide bond in the ring system.     

Synthesis and reactions of 1-hydroxy-9,9a-dihydro-1H-imidazo[1,2-a]indol-2-(3H)-ones

1-Hydroxy-9,9a-dihydro-1H-imidazo[1,2-a]indol-2(3H)-ones, as a new type of azaheterocyclic hydroxamic acids, have been synthesized regioselectively from 1-carbamoylmethyl- or 1-(methoxycarbonyl)methyl-2,3,3-trimethyl-3H-indolium salts by reaction with hydroxylamine in the presence of a strong base. The alkylation and reduction with sodium borohydride of these novel heterocycles have been investigated. When treated with protic acids 1-hydroxy- or 1-alkoxy-9,9a-dihydro-1H-imidazo[1,2-a]indol-2(3H)-ones underwent ring opening of the imidazolidine to afford 1-[2-(hydroxyamino)-2-oxoethyl]-2,3,3-trimethyl-3H-indolium salts. The structural assignments are based on extensive ¹H, ¹³C and ¹⁵N NMR spectroscopic studies and single crystal X-ray analyses.     

Preparative synthesis of 3- and 4-(3-alkoxy-4-acyloxyphenylmethylamino)benzoic acids

Reduction of 3- and 4-[(3-alkoxy-4-acyloxyphenyl)methylideneamino]benzoic acids (E isomers) with sodium triacetoxyhydridoborate in benzene gave the corresponding 3- and 4-(3-alkxy-4-acyloxyphenylmethyl) benzoic acids in preparative yields.     

Alcohols of the nitrofuran series

By reducing the corresponding aldehydes with sodium borohydride,α-ethyl-β-(5-nitro-2-furyl)allyl alcohol and 5-(5-nitro-2-furyl)penta-2, 4-dienol have been obtained. A number of their esters have been synthesized.     

Analogs of pyrimidine nucleosides

A new method for the synthesis ofN₁-(dihydroxyalkyl)uracils by reduction of substituted α- (1-uracilyl)- and γ-[(1-uracilyl)methyl]-γ-butyrolactones with sodium borohydride was found.     

New method for the asymmetric hydroboration of ketophosphonates and the synthesis of phospho-carnitine

The reduction of α- or β-ketophosphonates with a chiral reactant 1, prepared from sodium borohydride and (R)- or (S)-tartaric acids, led to the formation of both (S)- and (R)-α- or β-hydroxyphosphonates in high yields. The stereoselectivity of the reaction depended on the absolute configurations of 1 and the ketophosphonates. The reduction of di(1R,2S,5R)-menthyl ketophosphonates with (R)-1 proceeded with matched double asymmetric induction to give high diastereomeric excesses of hydroxyphosphonates (up to 96% de). This methodology was used for the preparation of enantiomerically pure phosphonate modified carnitine on a multigram scale.     

The solvent extraction of indium(III) with carboxylic acids

The extractions of l0^-5–10^-7M indium, from aqueous 0.1 M sodium perchlorate solutions into various organic media containing different concentrations of monocarboxylic acids and into pure monocarboxylic acids have been studied. Both saturated and unsaturated acids have been employed; the number of carbons in the acids was l–18. Detailed studies of one of the better systems, hexanoic acid in chloroform, have been carried out, the system has been described with a general overall equation, and identifications of the major species have been proposed.     

Reduction of 2,3,4-substituted quinolines with sodium borohydride

1,2-Dihydroquinolines were obtained by the reduction of 3-substituted 2-methyl-4-phenylquinolines with sodium borohydride in aliphatic carboxylic acids; N-alkyl derivatives are also formed. The corresponding 1,4-dihydroquinoline was obtained in the reaction of 2-methyl-3-nitroquinolinium perchlorate with sodium borohydride.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1680–1686, December, 1991.     

Asymmetric synthesis of 4-formyl-1-(ω-haloalkyl)-β-lactams and their transformation to functionalized piperazines and 1,4-diazepanes

Chiral piperazine and 1,4-diazepane annulated β-lactams, prepared from the corresponding (3R,4S)-4-imidoyl-1-(ω-haloalkyl)azetidin-2-ones through reduction with sodium borohydride in ethanol, were transformed into novel methyl (R)-alkoxy-[(S)-piperazin-2-yl]acetates and methyl (R)-alkoxy-[(S)-1,4-diazepan-2-yl]acetates upon treatment with hydrogen chloride in methanol. On the other hand, bromination of (3R,4R)-1-allyl-4-formyl-β-lactams and (3R,4S)-1-allyl-4-imidoyl-β-lactams in dichloromethane, followed by sodium borohydride reduction of the resulting dibrominated azetidin-2-ones in ethanol, did not afford the envisaged bicyclic β-lactams but unexpectedly furnished (3R,4S)-1-(2-bromo-2-propenyl)azetidin-2-ones instead.     

The determination of tellurium by nondispersive atomic fluorescence spectrometry using the hydride generation technique

Atomic fluorescence spectrometry with a nondispersive measuring system is combined with a hydride generation technique for the determination of tellurium. Atomic fluorescence measurement is based on the reduction of tellurium by either metallic zinc or sodium borohydride, introduction of the generated tellurium hydride into a premixed argon (entrained air)-hydrogen flame, and excitation with a tellurium electrodeless discharge lamp. The comparison of the zinc and the sodium borohydride reduction methods is discussed in terms of detection limit, precision and interference. The best attainable detection limits for tellurium are 2ng (0.1 $\text{ng}\text{ml}$) and 30 ng (1.5 $\text{ng}\text{ml}$) with the zinc and the sodium borohydride methods respectively. Analytical working curves obtained from peak-height and peak-area measurements are linear over a range of approximately 4 orders of magnitude. Of the mineral acids examined in the range up to 2.0 m. nitric acid gives a depressing interference in the range greater than 0.5 m in the zinc method, whereas all of the acids greater than 1.0 m give a slight enhancement of the signal in the sodium borohydride method. The presence of several elements including other hydride-forming elements in 1000-fold ratio to tellurium causes a depressing interference, while enhancing interferences from tungsten and vanadium are observed in the zinc and the sodium borohydride methods, respectively. The present system coupled with the zinc method has been applied to the determination of tellurium in several samples of high-purity copper metal after separation of the analyte from copper by passing an ammoniacal solution of the sample through Chelex-100 resin. The results are in good agreement with those obtained by graphite furnace atomic absorption spectrometry.     

Environmentally benign oxidation reaction of aldehydes to their corresponding carboxylic acids using Pd/C with NaBH4 and KOH

Pd/C catalyst in aqueous methanol with sodium borohydride and potassium hydroxide under the air efficiently oxidized aldehydes to their corresponding carboxylic acids at room temperature. The utilization of room temperature reaction, aqueous methanol solvent, and the open-air conditions make this manipulation very interesting for economic and environmental perspectives.     

Chemical synthesis of deuterium-labeled and unlabeled very long chain polyunsaturated fatty acids

First syntheses of a deuterium-labeled very long C34-containing polyunsaturated fatty acid, 34:5n5, and three other unlabeled very long chain C30-32 containing polyunsaturated fatty acids are reported. These syntheses were achieved by coupling chemically modified C22- and C20-containing polyunsaturated fatty acids with carbanions derived from arylalkyl sulfones, followed by sodium amalgam-mediated desulfonylation.     

The reaction of fluorine-containing compounds with conjugated dienoic acids initiated by sodium dithionite

The reaction of fluorine-containing halides and acetamides with conjugated dienoic acids initiated by sodium dithionite gave halide-free 1,4-adducts in 40-80% yields, with the E configuration as the major products.