Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Aldehydes reductive

In pharmaceutical appHcations, the selectivity of sodium borohydride is ideally suited for conversion of high value iatermediates, such as steroids (qv), ia multistep syntheses. It is used ia the manufacture of a broad spectmm of products such as analgesics, antiarthritics, antibiotics (qv), prostaglandins (qv), and central nervous system suppressants. Typical examples of commercial aldehyde reductions are found ia the manufacture of vitamin A (29) (see Vitamins) and dihydrostreptomycia (30). An acyl azide is reduced ia the synthesis of the antibiotic chloramphenicol (31) and a carbon—carbon double bond is reduced ia an iatermediate ia the manufacture of the analgesic Talwia (32). [Pg.304]

The NAD- and NADP-dependent dehydrogenases catalyze at least six different types of reactions simple hydride transfer, deamination of an amino acid to form an a-keto acid, oxidation of /3-hydroxy acids followed by decarboxylation of the /3-keto acid intermediate, oxidation of aldehydes, reduction of isolated double bonds, and the oxidation of carbon-nitrogen bonds (as with dihydrofolate reductase). [Pg.590]

Conjugate addition of methyl magnesium iodide in the presence of cuprous chloride to the enone (91) leads to the la-methyl product mesterolone (92) Although this is the thermodynamically unfavored axially disposed product, no possibility for isomerization exists in this case, since the ketone is once removed from this center. In an interesting synthesis of an oxa steroid, the enone (91) is first oxidized with lead tetraacetate the carbon at the 2 position is lost, affording the acid aldehyde. Reduction of this intermediate, also shown in the lactol form, with sodium borohydride affords the steroid lactone oxandrolone... [Pg.174]

Platinum, especially platinum oxide, has been used by many investigators (5), Platinum oxide, when used with aldehydes is apt to be deactivated before reduction is completed. Deactivation is inhibited by small amounts of ferrous or stannous chlorides (59,82). This type of promoter can also sharply curtail hydrogenolysis if it is a troublesome reaction (Rylander and Starrick, 1966). Deactivated systems can often be regenerated by shaking the reaction mixture with air (2,8,21 J3,96). The usefulness of this regenerative technique transcends aldehyde reductions it frequently is worth resorting to. [Pg.67]

The result is not totally surprising, because hydride ion shifts are known in many methylations. Thus, it was proposed that the methyl carbinol is formed by the sequence methylation of a double bond - hydride shift - formation of terminal methylene - epoxidation - opening of the epoxide to aldehyde - reduction to carbinol (Scheme 6). The pathway can explain well the loss of two original hydrogens in methionine methyl group. [Pg.23]

The catalyst derived from Rh6(CO)i6 is the most active catalyst for aldehyde reduction of all the group 8 metals we have studied (12,13). [Pg.137]

To have a basis for comparison, we established a standard run for aldehyde reduction consisting of... [Pg.138]

Catalysts and Catalyst Concentration. The most active catalyst for benzaldehyde reduction appears to be rhodium [Rh6(C0)i6 precursor], but iron [as Fe3(C0)i2] and ruthenium [as Ru3(C0)12] were also examined. The results of these experiments are shown in Table 1. Consistent with earlier results (12), the rhodium catalyst is by far the most active of the metals investigated and the ruthenium catalyst has almost zero activity. The latter is consistent with the fact that ruthenium produces only aldehydes during hydroformylation. Note that a synergistic effect of mixed metals does not appear to be present in aldehyde reduction as contrasted with the noticeable effects observed for the water-gas shift reaction (WGSR) and related reactions (13). [Pg.139]

The Effect of Reactant Concentration. Several experiments were conducted to quantify the effect of reactant concentration on the aldehyde reduction rate. The initial CO pressure was varied... [Pg.139]

Reduction of Other Aldehydes. We examined the reduction of anisaldehyde, p-CH30C6H4CH0 and tolualdehyde, p-CH3(C6H<,)CH0 to examine the effect of electron density on aldehyde reduction. In addition, we also investigated one ketone, acetophenone, C6H5C0CH3. The results of these experiments are given in Table 2. [Pg.141]

For example, a dienyl aldehyde reductively cyclizes in the presence of an Ni(0)/PPh3 complex and triethylsilane to give homoallylic cyclopropentanol with high regio- and stereoselectivities, while bishomoallylic cyclopropentanol is obtained as major product under the conditions using stoichiometric Ni(0)-diene complexes (Scheme 85). [Pg.456]

The first report of rhodium catalysts for aldehyde reduction came from Marko who reported the use of RhCl3 3H20 under hydroformylation conditions [9]. It was suggested that the active species were rhodium carbonyls, and the catalyst system was successfully utilized in the hydrogenation of ethanal, propanal, and benzalde-... [Pg.417]

It has been shown previously how water-soluble rhodium Rh-TPPTS catalysts allow for efficient aldehyde reduction, although chemoselectivity favors the olefmic bond in the case of unsaturated aldehydes [17]. The analogous ruthenium complex shows selectivity towards the unsaturated alcohol in the case of crotonaldehyde and cinnamaldehyde [31]. [Pg.423]

The water-soluble ligand (TPPTS) was discussed earlier with regard to aldehyde reduction [17]. Similarly, in ketone transfer hydrogenation, high yields are obtained for a variety of substrates with the ability for efficient catalyst recycling at no expense of activity or selectivity (Fig. 15.10). [Pg.430]

Aldehyde oxidation Aldehyde reduction Ketone reduction... [Pg.343]

CHEC-II(1996) <1996CHEC-II(8)345> covered a range of reactions of substituents, including hydrolyses of esters to carboxylic acids and geminal dihalides to aldehydes, reduction of aldehydes and halogens directly attached to the ring, O-methylation with diazomethane, and reduction of nitroso compounds. A selection of reactions which have... [Pg.563]

Enantioselective synthesis of R R2CHNH2.1 Alkyllithiums add stereoselec-tively to the C=N bond of SAMP hydrazones (2) of aldehydes. Reductive cleavage of the N—N bond of the products (3) affords either (R)- or (S)-4 with recovery of... [Pg.22]

Aldehydes and ketones are readily reduced back to primary and secondary alcohols, respectively. In the case of ketones, although the reduction is reversible, ketoreductase utilizes NADPH, the concentration of which is higher than NADP+, and this drives the reaction toward the secondary alcohol. A good example is warfarin as shown in Figure 5.3 (19). However, aldehydes are further oxidized to carboxylic acids and carboxylic acids are not reduced back to aldehydes thus eliminating the aldehyde. Reductive metabolism of esters and amides also does not generally occur. [Pg.116]


See other pages where Aldehydes reductive is mentioned: [Pg.64]    [Pg.610]    [Pg.27]    [Pg.35]    [Pg.12]    [Pg.14]    [Pg.747]    [Pg.747]    [Pg.748]    [Pg.749]    [Pg.749]    [Pg.749]    [Pg.750]    [Pg.752]    [Pg.752]    [Pg.752]    [Pg.754]    [Pg.755]    [Pg.755]    [Pg.756]    [Pg.756]    [Pg.756]    [Pg.756]    [Pg.49]    [Pg.138]    [Pg.428]    [Pg.91]    [Pg.243]    [Pg.111]   
See also in sourсe #XX -- [ Pg.742 , Pg.743 ]




SEARCH



6-Hydroxy aldehydes, dehydration reduction

ALDEHYDES FROM ACID CHLORIDES BY REDUCTION

Acid chlorides, reduction to aldehydes

Alcohol dehydrogenase aldehyde reduction

Alcohols by reduction of aldehydes

Alcohols, From reduction of aldehydes Reagents which can be used to reduce

Alcohols, preparation by reduction of aldehydes

Aldehyde acetals, reduction

Aldehyde biological reduction

Aldehyde chemoselective reduction

Aldehyde derivatives, reduction

Aldehyde diacetates, reduction

Aldehyde oxidase reduction

Aldehydes Clemmensen reduction

Aldehydes Meerwein-Ponndorf reduction

Aldehydes Meerwein-Ponndorf-Verley reduction

Aldehydes acyl derivative reduction

Aldehydes addition reduction

Aldehydes alcohols, reduction

Aldehydes amide reduction

Aldehydes amino, reduction

Aldehydes asymmetric reductions

Aldehydes bimolecular reduction

Aldehydes by reduction

Aldehydes by reduction of nitriles

Aldehydes carboxylic acid reduction

Aldehydes catalytic reduction

Aldehydes conjugate reductions, sodium borohydride

Aldehydes continued reductive coupling reactions

Aldehydes direct reductive aminations

Aldehydes dissolving metal reductions

Aldehydes enzymatic reduction

Aldehydes enzymic reduction

Aldehydes ester reduction

Aldehydes from Weinreb amide reduction

Aldehydes from carboxylic acid reduction

Aldehydes from ester reduction

Aldehydes heterocyclic, reduction

Aldehydes in reductive amination

Aldehydes metal hydride reductions

Aldehydes ozonide reduction

Aldehydes reduction

Aldehydes reduction

Aldehydes reduction by metal hydrides

Aldehydes reduction by sodium borohydride

Aldehydes reduction reactions

Aldehydes reduction to alcohols

Aldehydes reduction to hydroxyls

Aldehydes reductions, carbon-nitrogen

Aldehydes reductive amidation

Aldehydes reductive amination

Aldehydes reductive aminations, palladium®) acetate

Aldehydes reductive aminations, sodium cyanoborohydride

Aldehydes reductive coupling

Aldehydes reductive coupling with

Aldehydes reductive dimerization

Aldehydes reductive halogenation

Aldehydes reductive iodination using

Aldehydes reductive metallation

Aldehydes reductive reactions

Aldehydes, Wolff-Kishner reduction

Aldehydes, a-amino via ester reduction

Aldehydes, acetal formation from reduction

Aldehydes, aliphatic reduction

Aldehydes, aliphatic, olefinic reduction

Aldehydes, allenic reduction

Aldehydes, aromatic reduction

Aldehydes, conjugated LiAlH4 reduction

Aldehydes, halogenated, reduction

Aldehydes, halogenation reduction

Aldehydes, hydroxy, reduction

Aldehydes, nitro, reduction

Aldehydes, olefinic reduction

Aldehydes, oxidation reduction

Aldehydes, phytochemical reduction

Aldehydes, reduction with DIBAL

Aldehydes, reduction with Grignard reagents

Aldehydes, reduction with LiAlH

Aldehydes, reduction with NaBH

Aldehydes, reduction with Selectride

Aldehydes, reduction with aluminum borohydride

Aldehydes, reduction with cyanoborohydride

Aldehydes, reduction with silanes

Aldehydes, reduction with tributyltin hydride

Aldehydes, reduction, transfer

Aldehydes, reduction, transfer hydrogenation

Aldehydes, reductive alkylation

Aldehydes, reductive alkylation alkenes, reagents

Aldehydes, reductive alkylation reagents

Aldehydes, reductive alkylation tautomerism

Aldehydes, reductive alkylation vinylation

Aldehydes, reductive alkylation with alcohols

Aldehydes: aldol type reactions reductive coupling

And reduction of aldehydes

Aryl aldehydes, reductive coupling

Aryl aldehydes, reductive coupling addition

Aryl aldehydes, reductive coupling bromides

Aryl aldehydes, reductive coupling reaction

Asymmetric reduction of aldehydes

Asymmetric reduction of aldehydes and ketones

Biological reaction, alcohol aldehyde reduction

Borane selective aldehyde and ketone reduction

Borohydrides selective aldehyde reduction

Chemoselective reduction of aldehyd

Cinnamic aldehyde reduction

Clemmensen reduction aromatic aldehydes

Conjugated aldehydes 1,4-reduction

Diene-Aldehyde Reductive Cyclizations

From reduction of aldehydes and ketones

Halo aldehydes, reduction

Hydride reduction of aldehydes and ketones

Hydrogenolysis of Acid Chlorides to Aldehydes (the Rosenmund Reduction)

Imidazoles, reduction aldehydes

Indole aldehyde, reduction

Ketones and aldehydes, distinguishing from reduction

Lithium diisopropylamide aldehyde reduction

Mechanism aldehyde reduction

Mechanism borohydride reduction of aldehydes and

Nitriles reduction to aldehydes

Nitro aldehydes, aromatic, reduction

Nitro aldehydes, aromatic, reduction preparation

Nitro groups, reduction aldehydes

Organosilane Reduction of Aldehydes

Organosilane Reductive Amination of Aldehydes and Ketones

Primary alcohol aldehyde reduction product

Pyrrole aldehydes, reduction

Quinoline, 8-oxydihydroboronite selective aldehyde reduction

REDUCTION REACTIONS OF ALDEHYDES AND KETONES

REDUCTION, OF CARBOXYLIC ACIDS TO ALDEHYDES

ROSENMUND - SAITZEW Reduction aldehydes

Raney nickel alloy, reduction of aromatic nitriles to aldehydes

Reaction XII.—Reduction of Aldehydes and Ketones to Pinacones

Reduction aldehyde ketone

Reduction aldehydes and ketones

Reduction of Acid Derivatives to Aldehydes

Reduction of Aldehyde and Ketone Carbonyls

Reduction of Aldehydes and Ketones Using Whole Cells

Reduction of Aldehydes and Ketones to Alcohols

Reduction of Aldehydes and Ketones to Hydrocarbons

Reduction of Aldehydes and Ketones with Poly(Methylhydrosiloxane)

Reduction of Aldehydes in Preference to Ketones

Reduction of Aldehydes, Ketones, and Carboxylic Acid Derivatives

Reduction of Aliphatic Aldehydes

Reduction of Aromatic Aldehydes

Reduction of Conjugated Aldehydes in Preference to Enones

Reduction of Enones in Preference to Aldehydes

Reduction of a Nitrile to an Aldehyde

Reduction of acid chlorides to aldehydes

Reduction of aldehydes

Reduction of aldehydes and ketones

Reduction of aldehydes or ketones

Reduction of unsaturated aldehydes and ketones

Reduction reaction aldehydes/ketones

Reduction to aldehydes

Reduction, acid chlorides aldehydes

Reductions of Carboxylic Acid Derivatives to Aldehydes

Reductions of a, 3-unsaturated aldehydes and ketone

Reductive Coupling Reactions of Aryl Aldehydes

Reductive Coupling of Alkynes and Aldehydes

Reductive alkylation of aldehydes and ketones

Reductive amination aldehyde-mPEG derivative

Reductive amination of aldehydes

Reductive amination, of aldehydes and

Reductive aminations aldehydes

Reductive coupling, of aldehydes

Reductive enzymes aldehyde oxidase

Reductive of aromatic aldehydes

Reductive of ketones and aldehydes

Selective Reduction Between Aldehydes

Selective aldehyde reduction

Sodium Borohydride Reduction of an Aldehyde or Ketone

Sodium aldehyde reduction with

Sodium borohydride selective aldehyde reduction

The Phytochemical Reduction of Aldehydes

The Reductive Amination of Aldehydes with Monoalkylureas

The reduction of aldehydes and ketones

The reduction of aldehydes, ketones and esters

Thioamides, reduction aldehydes

Unsaturated aldehydes Bakers’ yeast reduction

Unsaturated aldehydes organocatalytic reduction

Unsaturated aldehydes reduction

Wolff-Kishner reduction, of aldehydes and

Wolff-Kishner reduction, of aldehydes and ketones

© 2024 chempedia.info