Reduction Of Carbonyl Group Research Articles

Synthesis of an inhibitor of sphingosine-1-phosphate lyase

The 2-vinyl dihydrosphingosine-1-phosphate 1 was synthesized and tested for inhibition of sphingosine-1-phosphate lyase. The carbon skeleton was prepared by acylation of a methionine imine with N-methoxy-N-methyl palmitamide. The vinyl group was generated by thermal sulfoxide elimination. Reduction of both carbonyl groups and deprotection gave 2-vinyl dihydrosphingosine. The phosphate group was introduced by means of bis(2-cyanoethyl)-N,N-diisopropyl-phosphoramidite as monofunctional phosphitylation reagent.

Lithium borohydride-catalysed selective reduction of carbonyl group of conjugated and unconjugated alkenones with borane in tetrahydrofuran

In the presence of a catalytic amount of LiBH4, BH3 in THF selectively reduced the carbonyl group of conjugated and unconjugated alkenones at –50 °C to quantitatively provide the corresponding alkenols on subsequent hydrolysis.

Polyhydroxy alcohols as hydrogen donors in catalytic transfer reduction of carbonyl groups over MgO

The catalytic transfer reduction of benzaldehyde with polyhydric alcohols has been studied over MgO. 1,3-Propanediol, 1,4-butanediol, 1,6-hexanediol, 1,2,6-hexanetriol and triethylene glycol were found to be effective reductants for the carbonyl group. Vicinal diols such as 1,2-ethanediol and 1,2-propanediol did not exhibit any activity in the transformation studied. 1,4-Butanediol was successfully used in the large laboratory scale CTR of benzaldehyde.

ChemInform Abstract: Montmorillonite Supported Phase‐Transfer Catalyst in Reduction of Carbonyl Groups.

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.

Stereocontrolled synthesis of the 4-hydroxy-5-methyl-2(3H)-dihydrofuranone isomers

A synthesis of all four stereoisomers of 4-hydroxy-5-methyl-2(3H)-dihydrofuranone was achieved in 6 or 7 steps with an overall yield of 19% to 23% from a common starting material. The source of chirality being derived from stereoselective bakers' yeast reductions of carbonyl groups.

機械パルプの微生物処理に関する研究 第６報 機械パルプの光退色抑制におよぼすカルボニル基の影響

Reduction of acetophenone derivatives as a model compound for having α-carbonyl group was conducted to find out the effect of carbonyl groups, especially α-carbonyl group, in mechanical pulps on light-induced color reversion. The model compounds could not be almost reduced with potassium borohydride (KBH4) only, however, the reduction was effectively proceeded by addition of small amount of phase transfer catalyst (PTC). The methyl ether derivatives of acetophenones having no free phenolic hydroxyl group could be reduced with KBH4 accompanied with PTC to the corresponding alcohols in almost quantitative yields in a short time. On the contrary, in the case of the compounds having free phenolic hydroxyl group the reaction proceeded only about 20 to 30 % on the reduction. However, the carbonyl group could be reduced about 75 to 90 % when the phenolic hydroxyl group was blocked as acetate and followed by the reduction. In addition, the reduction products were further deacetylated during the reduction to the corresponding alcohols having free phenolic hydroxyl group.Based on the results obtained from the model experiments, effect of reduction of carbonyl groups in mechanical pulps on light-induced color reversion was examined. Light-induced color reversion of groundwood pulp (GP), thermomechanical pulp (TMP), and pressurized groundwood pulp (PGW) could be depressed 33-44%, 11-19%, and 11-23%, respectively, to that of untreated pulps by pretreatment of unbleached mechanical pulps with KBH4 accompanied with PTC. And furthermore, the color reversion of GP, TMP, and PGW was also depressed 24-39%, 12-24%, and 10-26%, respectively, to that of untreated one when bleached mechanical pulps were treated with KBH4 accompanied with PTC.The results showed that the effect of carbonyl groups in GP, TMP, and PGW on light-induced color reversion could be suggested about 30 %, 15 %, and 15 %, respectively. It has been said that carbonyl groups, especially, α-carbonyl group in mechanical pulps are greatly responsible for the color reversion. From the results obtained here, however, it is considered that carbonyl groups in mechanical pulps do not contribute so greatly to the color reversion, though α-carbonyl group functions as a photosensitizer on light-induced color reversion of mechanical pulps.

Montmorillonite Supported Phase Transfer Catalyst in Reduction of Carbonyl Groups

Abstract Silylpropyltrimethylammonium iodide covalently anchored onto montmorillonite shows good catalytic activity in carbonyl reduction under triphase catalysis. Selectively trans-t-butylcyclohexanol was formed selectively in good yield in the reduction of 4-t-butylcyclohexanone. the catalyst was resued for several cycles.

Light-Induced Yellowing of Mechanical and Ultra-High Yield Pulps. I. Effect of Methylation, NaBH4, Reduction and Ascorbic Acid on Chromophore Formation

Abstract Absorption difference spectra of bleached TMP irradiated with near-uv light exhibited two apparent absorption maxima at π 410 nm and 330 nm. Experiments with borohydride-reduced pulp suggest that photochemical formation of aromatic carbonyls contributes to the λ = 330 nm peak. Chromophore formation followed an apparently first-order rate law, and the rate was unaffected by methylation of phenolic hydroxyl groups, or by exhaustive reduction of carbonyl groups with NaBH4. Methylation of phenolic hydroxyl, while having no effect on the kinetics of chromophore formation, did decrease the maximum change in absorption coefficient, ΔK∞. Treatment of bleached TMP with ascorbic acid slowed light-induced yellowing substantially; significant yellowing occurred only after 2 hours. Light-induced bleaching of a chromophore with λmax π 350 nm, possibly a stilbene, occurred during the first 90 minutes of irradiation.

Hydrogenation activity and selectivity of cobalt borides

Hydrogenation of monofunctional (olefinic and carbonyl) and bifunctional (α, β-unsaturated aldehyde) compounds have been studied over cobalt borides. The cobalt borides P-ICo and P-2WCo were prepared by reducing cobalt acetate with sodium borohydride in aqueous and 50% ethanolic media, respectively. P-1Co is more active than P-2WCo for hydrogenation of olefinic groups, whereas P-1Co is less active for carbonyl groups. Chromium and molybdenum effectively promote P-1Co and P-2WCo in carbonyl group reduction, but chromium depresses P-1Co and P-2WCo on olefinic group reduction. P1Co and P-2WCo can selectively reduce benzene to cyclohexene and α, β-unsaturated aldehyde to unsaturated alcohol, reactions that are difficult on other heterogeneous catalysts.

ChemInform Abstract: Thermochemical Studies of Carbonyl Compounds. Part 5. Enthalpies of Reduction of Carbonyl Groups.

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.

Stereospecific solid state sodium borohydride reductions of cage dikotenes

Solid state reductions of carbonyl groups in three cage diketones, 1a-1c, have been performed by using sodium borohydride, and the results thereby obtained have been compared with the corresponding reductions performed in ethanol solution. In each case, the solid state reduction proceeds stereospecifically; hydride transfer occurs exclusively at the exo face of the carbonyl group. In contrast, the corresponding homogeneous (solution-phase) reductions display only moderate stereoselectivity.

Thermochemical studies of carbonyl compounds. 5. Enthalpies of reduction of carbonyl groups

The enthalpies of reduction of aldehydes and ketones to the corresponding alcohols have been determined by measuring the enthalpies of reaction of the carbonyl compounds and of the alcohols with lithium triethylborohydride in triglyme. The enthalpy of reduction of ethyl acetate to ethanol was determined in the same fashion. Enthalpies of formation of the carbonyl compounds were derived from the reduction data. The trends in the ΔH f values for a series of aldehydes and of ketones were examined, and the ΔH f values also were compared with the predictions derived with the MM3 molecular mechanics procedure

ChemInform Abstract: Selective Reduction of Carbonyl Groups with Systems Composed of (η 5‐C5H5)2MoH2 and Protonic Acids: New Highly Regio‐ and Diastereoselective Reduction of Ketones.

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.

Enantioselectivity in microbial reduction of prochiral carbonyl groups: A wide screening toward R and S isomers

More than fifty yeast and mould strains were tested in the reduction of 2-acylthiazoles 1–5. The possibility of obtaining R or S enantiomers with high enantioselectivities from various species and strains is described.

ChemInform Abstract: Selective Reduction of the Carbonyl Group of Functional Nitroaromatic Derivatives: A New Application of Complex Reducing Agents ZnCRASi.

The selective reduction of carbonyl group of aromatic nitroketones or aldehydes into aromatic nitroalcohols has been achieved by Me3SiCl modified Zinc containing Complex Reducing Agent (ZnCRASi).

Selective reduction of less reactive carbonyl groups in the presence of diborane and sodium bisulfite on silica gel

The less reactive carbonyl group of a mixture of reducible groups of carbonyl compounds was preferentially reduced with diborane on silica gel by first forming an adduct of the more reactive carbonyl group with sodium bisulfite. For example, 4-acetylbenzaldehyde could be converted to 4-(1-hydroxylethyl)benzaldehyde in 93% selectivity; in a mixture of 4-phenyl-acetophenone and 4-phenylbenzaldehyde, biphenylethanol was preferentially formed in 95% yield with 16% yield of 4-phenylbenzyl alcohol. Silica gel and sodium bisulfite were essential for this selective reaction. Aliphatic and aromatic aldehydes and unhindered cyclohexanones could be selectively protected by this method. Keywords: sodium bisulfite, silica gel, carbonyl compound, selective reduction, diborane.

Selective Reduction of the Carbonyl Group of Functional Nitroaromatic Derivatives: A New Application of Complex Reducing Agents ZnCRASi

Abstract The selective reduction of carbonyl group of aromatic nitroketones or aldehydes into aromatic nitroalcohols has been achieved by Me3SiCl modified Zinc containing Complex Reducing Agent (ZnCRASi).

Stereoselectivity of the enzymatic reduction of aldehydic and ketonic carbonyl groups in planar chiral organomanganese complexes.

(±)-Tricarbonyl(η5-1-formyl-2-methylcyclopentadienyl)manganese (1) was optically resolved with horse liver alcohol dehydrogenase (HLADH) and two species of yeasts, Saccharomyces sp. H-1 and Rhodotorula rubra IFO 889. Usually, (1R)-1 was preferentially reduced to give (−)-alcohol 2 of ≥ 97% e.e. − 84% e.e. Ketone analogue (±)-tricarbonyl(η5-1-acetyl-2-methylcyclopentadienyl)-manganese (4) was reduced by the yeasts. The major product by S. sp. H-1 was the (1S,2R,1′S)-(+)-alcohol (5) (≥ 98% e.e.) and the minor product, the (1R,2S,1′S)-(−)-alcohol (6) (86% e.e.). R. rubra gave only the latter alcohol (≥ 99 % e.e.). The Stereodifferentiation mechanism for these bioreductions is discussed in terms of the Prelog rule. The mechanism for HLADH reduction was examined with computer graphics.

Baker's Yeast as a Reagent in Organic Synthesis

This review examines the use of baker's yeast as a reagent in organic synthesis, with an emphasis on the developments of the last 15 years. The transformations of various classes of compounds are examined, for example, reduction or formation of double bonds, acyloin condensation. The equivalent microbial transformations are compared in relevant cases. 1. Introduction 2. Reduction of β-Keto Esters 3. Reduction of other Keto Acid Derivatives 4. Reduction of α-Hydroxy Aldehydes and Ketones to Vicinal Diols 5. Reduction of Ketones with a Sulfur Containing Functional Group on the α-Carbon 6. Reduction of β-Diketones 7. Reduction of Carbon-Carbon Double Bonds 7.1. Preparation of Bifunctional Chiral Synthetic Building Blocks 7.2. Reduction of Trisubstituted Double Bonds of Larger Synthetic Intermediates 7.3. Reduction of other Trisubstituted Double Bonds 8. Formation of Carbon-Carbon Bonds 8.1. Acyloin Condensation 8.2. Enzymatic Cyclization of Squalenoids 8.3. Carbon-Carbon Bond Formation through Michael-Type Addition 9. Reduction of Carbonyl Groups for the Preparation of Optically Active Fluorinated Compounds 10. Reduction of Heterocyclic Ketones 11. Reduction of Aromatic and Unsaturated Ketones 12. Kinetic Resolution of Cyclic Racemic Ketones 13. Reduction of Nitro Containing Compounds 14. Ester Hydrolysis 15. Water Addition Across the Double Bond of α,β-Unsaturated Aldehydes 16. Dehydrogenation of Unnatural Fatty Acids

Regiospecificity and Enantiospecificity in Microbiological Reduction of Acyclic β-Diketones

A screening of microorganisms has been performed to study the regio- and stereospecificities of the reduction of carbonyl groups in 2,4 and 3,5 diketones to obtain all stereoisomers. (2S), (2R), (3S), (3R) and (5R) ketols are obtained along with (2S, 4S) and (3S, 5S) diols often in high optical yields. Chemo-enzymatic methodologies to obtain stereoisomers not reached by direct microbiological reduction are discussed.