Zinc Borohydride Research Articles

Zinc Borohydride - A Reducing Agent with High Potential

Several new and novel applications of Zinc borohydride, a non-conventional hydride reducing agent, have been demonstrated for efficient chemo- and regioselective reductions of various important functionalities. These include : (a) chemoselective reduction of aldehydes over ketones; (b) chemoselective reduction of saturated ketones and conjugated aldehydes over conjugated enones; (c) chemoselective reduction of aliphatic ester over aromatic one; (d) chemoselective reduction of carboxylic acids; (e) chemoselective reduction of 2-nitrocycloalkanones to 2-nitrocycloalkanols; (f) highly selective reduction of monosubstituted conjugated nitroalkenes to the corresponding nitroalkanes and disubstituted ones to the corresponding oximes; (g) regio- and stereoselective reductive cleavage of unsymmetrical alkyl-substituted epoxide to the less-substituted alcohol; (h) regioselective 1,2-reduction of conjugated ketones and aldehydes; and (i) regioselective hydration of alkenes to the less-substituted alcohols.

Synthesis and Amino Acid Chain Extension of 1-Acylated Hydroxymethylpyrroles

Acylation of pyrrole-2-carbaldehyde (3) with an N-phthaloyl amino acid chloride, N,N-diisopropylethylamine and 4-dimethylaminopyridine (dmap) gave the 1-acylpyrrole-2-carbalde-hydes (4a-c). The 1-acylated pyrroles (4d-i), (8) and (9) were similarly prepared in good yields from the relevant pyrrole derivative using dmap and either an acid chloride/N,N- diisopropylethylamine or an anhydride/triethylamine. Reduction of (4a-f) with zinc borohydride gave the 1-acylated hydroxymethylpyrroles (5a-f). A coupling of (5a) with N-Cbz-L-Val-L-Val-OH under Mitsunobu conditions gave the tetrapeptide analogue (11).

Structures of Insect Antifeeding Limonoids, Trichilins F and G, from Trichilia roka

Two new limonoids, trichilins F and G, have been isolated from the root bark of Trichilia roka and identified as antifeedant against some pest insects. Their structures were determined from spectral data and chemical means, in which the treatment of trichilin A with zinc borohydride induced an acyl migration to yield trichilin F

Cyclisation of 4-[2-Cyclofentenyl]-3-Hydroxy [1] Benzopypan-2-One

Abstract 4-[2-cyclopentenyl]-3-hydroxy [1] bonzopyran-2-one(3) was cyclised to the bicyclie coumar in-1,3-ethano-2-bromo-1,2-dihydro-3H-pyrano [2,3-c] [1] benzopyran-5-one (6) by a sequence of reactions viz. acetylation of 3, addition of bromine to cyclopenteny double bond and treating the resulting acetyldibromo compound (5) with 4% alcoholic KOH, Cyclisation of compound (3) with mercuric acetate in methanol gave condensed furan derivative 7 which on reductive demercuration with zinc borohydride in dimethoxyethane gave the 1,3-propano-1,2-dihydrofuro [2,3-c] [1] benzopyran-4-one, 8. Cyclisation of compound 2 with come. H2SO4 furnished a mixture of bicyclic derivative 9 ad furo coumarin derivative 8.

ChemInform Abstract: Highly Selective Reduction of Conjugated Nitroalkenes with Zinc Borohydride in DME.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Highly selective reduction of 2-nitrocycloalkanones to 2-nitrocycloalkanols with zinc borohydride in DME

Clean and efficient reduction of 2-nitrocycloakanones to 2-nitrocycloalkanols has been achieved using zinc borohydride in 1,2-dimethoxyethane.

Reduction of conjugated nitroalkenes with zinc borohydride. A mild method for converting monosubstituted nitroalkenes to nitroalkanes and disubstituted ones to oximes

Mono-β-substituted conjugated nitroalkenes are readily reduced by zinc borohydride in 1,2-dimethoxyethane to the corresponding nitroalkanes, whereas the disubstituted ones furnish the corresponding oximes in excellent yields.

Selective reduction of carboxylic acids with zinc borohydride in the presence of trifluoroacetic anhydride

A simple and convenient procedure for the reduction of carboxylic acids to the corresponding alcohols has been developed using a solution of zinc borohydride in 1,2-dimethoxyethane in the presence of trifluoroacetic anhydride.

Silica gel-supported zinc borohydride. Part 3. Regioselective reductive cleavage of methylenecycloalkane oxides to the less-substituted alcohols

Highly selective reductive cleavage of methylenecycloalkane oxides to less-substituted alcohols has been achieved by a simple procedure using silica gel supported zinc borohydride in tetrahydrofuran.

Cross-Linked Polyvinylpyridine Supported Zinc Borohydride as a Highly Chemoselective Reducing Agent

Abstract Aldehydes are reduced in ethanol under reflux condition in high yelds. This reagent absolutely discriminates aldehydes from ketones.

Highly selective reduction of conjugated nitroalkenes with zinc borohydride in DME

Zinc borohydride in 1,2-dimethoxvethane reduces α-substituted conjugated nitroalkenes to the corresponding oximes and non-α-substituted ones to the corresponding nitroalkanes in excellent yields.

Use of zinc borohydride for efficient reduction of carboxylic ester to alcohol. Seleclive reduction of aliphatic ester in presence of aromatic ester under sonication

An efficient methodology using zinc borohydride under sonification for the reduction of carboxylic esters to alcohols in presence of N,N-dimethylaniline and selective reduction of an aliphatic ester over an aromatic one without N,N-dimethylaniline is described.

Silica gel-supported zinc borohydride. 2. Regioselective 1,2-reduction of conjugated ketones and aldehydes to the corresponding allylic alcohols

Silica gel-supported zinc borohydride. 2. Regioselective 1,2-reduction of conjugated ketones and aldehydes to the corresponding allylic alcohols

Use of zinc borohydride as an efficient and highly selective reducing agent. Selective reduction of ketones and conjugated aldehydes over conjugated enones

Use of zinc borohydride as an efficient and highly selective reducing agent. Selective reduction of ketones and conjugated aldehydes over conjugated enones

ChemInform Abstract: A Mild Reduction of Azomethines with Zinc Borohydride. Synthetic Application to Tandem Alkylation‐Reduction of Nitriles.

AbstractSeven secondary amines such as (II) are prepared by reduction of the corresponding azomethines (I) with zinc borohydride.

ChemInform Abstract: Synthesis, Properties and Thermal Decomposition of the Hydrazinate of Zinc Borohydride.

AbstractReaction between Zn(BH4)2 (I) and anhydrous N2H4 (II) yields the hitherto unknown title compound (III).

Chemoselective reduction of aldehydes with zinc borohydride in tetrahydrofuran

A variety of structurally different aldehydes undergo chemoselectire reduction over ketones with zinc borohydride in tetrahydrofuran at −10°C to the corresponding alcohols.

A Mild Reduction of Azomethines with Zinc Borohydride. Synthetic Application to Tandem Alkylation-Reduction of Nitriles

The reduction of Schiff bases; N-benzylidene- and N-(1-phenylethylidene)arylamines with zinc borohydride in diethyl ether gave the corresponding amines in excellent yield. N-benzylidene-benzyl- and cyclohexylamine, N-(1-phenylethylidene)- and N-(cyclohexylidene)cyclohexylamines, however, require additional treatment with 6 N HCl to liberate the amine-borane complex to give the corresponding amines in quantitative yield. The procedures was also applied in the tandem alkylation―reduction of nitriles to yield 1-phenylalkylamines in good yield

Stereoselective syntheses of ephedrine and related 2-aminoalcohols of high optical purity from protected cyanohydrins

Ephedrine and related optically active β-aminoalcohols can be prepared by zinc borohydride reduction of aryl O-protected magnesium imines and aryl α-hydroxyimines which in turn are readily available from optically active cyanohydrins.

Stereoselective synthesis of either (±)-exo- or (±)-endo-brevicomin via hydride reduction of a 2-acylpyranyl intermediate

Reduction of the ethyl ketone (5) with L-Selectride or zinc borohydride proceeds stereoselectively to give the alcohols syn-(6) or anti-(7), respectively, which are converted, in turn, into (±)-exo-brevicomin and (±)-endo-brevicomin.