Search results for "Decarboxylation"

Synthesis of α-aminonitriles using aliphatic nitriles, α-amino acids, and hexacyanoferrate as universally applicable non-toxic cyanide sources

2018

In cyanation reactions, the cyanide source is often directly added to the reaction mixture, which restricts the choice of conditions. The spatial separation of cyanide release and consumption offers higher flexibility instead. Such a setting was used for the cyanation of iminium ions with a variety of different easy-to-handle HCN sources such as hexacyanoferrate, acetonitrile or α-amino acids. The latter substrates were first converted to their corresponding nitriles through oxidative decarboxylation. While glycine directly furnishes HCN in the oxidation step, the aliphatic nitriles derived from α-substituted amino acids can be further converted into the corresponding cyanohydrins in an oxi…

2018

A visible light-promoted protocol for the redox-neutral coupling of N-hydroxyphthalimide esters with different N-heterocyclic compounds is described. The reaction proceeds through an alkyl radical intermediate generated by reductive decarboxylation of N-hydroxyphthalimide esters. In contrast to the original Minisci protocol, polyalkylation can largely be avoided. Mechanistic investigations revealed a radical chain mechanism which in some cases can proceed even if no photocatalyst is added. This valuable and functional group-tolerant reaction produces substituted heterocycles in moderate to excellent yield. The use of inexpensive starting materials and LEDs as the light source are key featur…

Electrochemical carboxylation of benzal chloride

1984

Abstract The clectrocarboxylation of benzal chloride to -chlorophenylacetic and phenylmalonic acids is realized in diaphragmless cells with aluminium sacrificial anodes. Yields respectively up to 50% and 30% can be obtained. Phenylacetic acid is always present among the products.

The 2-oxoglutarate binding site of prolyl 4-hydroxylase. Identification of distinct subsites and evidence for 2-oxoglutarate decarboxylation in a lig…

1984

The structure and function of the 2-oxoglutarate binding site of prolyl 4-hydroxylase was studied by assaying the inhibitory potential of 24 selected aliphatic or aromatic compounds. All except one of them inhibited the enzyme competitively with respect to 2-oxoglutarate and noncompetitively with respect to Fe2+, the Ki values ranging from 0.8 microM to over 15 mM. The Ki values for the two most effective inhibitors, pyridine 2,5-dicarboxylate and 2,4-dicarboxylate, were about 0.8 microM and 2 microM, these compounds being the most potent inhibitors of prolyl 4-hydroxylase with respect to 2-oxoglutarate known so far. Only one of the compounds tested, 2-oxoadipinate, was able to support hydr…

Nucleophilic benzoylation using lithiated methyl mandelate as a synthetic equivalent of the benzoyl carbanion. Oxidative decarboxylation of α-hydroxy…

2001

Abstract The synthesis of alkyl aryl ketones using lithiated methyl mandelate as a synthetic equivalent of the benzoyl carbanion is reported (Umpolung). The methodology involves alkylation of methyl mandelate, hydrolysis of the ester group and oxidative decarboxylation of the resulting α-hydroxyacids. The last step is carried out in a catalytic aerobic way using a Co(III) complex in the presence of pivalaldehyde under very mild and advantageous conditions. The procedure is also applied to methyl mandelates substituted on the aromatic ring.

(S)-Mandelic acid enolate as a chiral benzoyl anion equivalent for the enantioselective synthesis of non-symmetrically substituted benzoins

2011

A strategy for the enantioselective synthesis of non-symmetrically substituted benzoins from (S)-mandelic acid and aromatic aldehydes has been developed. This strategy is based on a diastereoselective aldol reaction of the lithium enolate of the 1,3-dioxolan-4-one derived from (S)-mandelic acid and pivalaldehyde with aromatic aldehydes, which gives the corresponding aldols in good yields. Subsequent hydroxyl group protection as MEM ethers, basic hydrolysis of the dioxolanone ring, oxidative decarboxylation of the α-hydroxy acid moiety, and hydroxyl group deprotection provides chiral non-symmetrically substituted benzoins with high enantiomeric excesses.

Highly Diastereoselective Arylation of (S)-Mandelic Acid Enolate: Enantioselective Synthesis of Substituted (R)-3-Hydroxy-3-phenyloxindoles and (R)-B…

2005

An easy access to substituted (R)-3-hydroxy-3-phenyloxindoles, (R)-benzylic acids, and benzophenones is described. The reaction of the lithium enolate of the (2S,5S)-cis-1,3-dioxolan-4-one derived from optically active (S)-mandelic acid and pivalaldehyde with several o- and p-halonitrobenzenes proceeds readily to give the corresponding arylation products in good yields and diastereoselectivities. The reduction of the nitro group with Zn/HCl/EtOH in the o-nitro arylation products with concomitant intramolecular aminolysis of the dioxolanone moiety leads directly to enantiomerically pure (R)-3-hydroxy-3-phenyloxindoles. On the other hand the basic hydrolysis of the dioxolanone moiety in all t…

Polymorphic and solvate structures of ethyl ester and carboxylic acid derivatives of WIN 61893 analogue and their stability in solution

2014

3-Ethyl ester- (1) and 3-carboxylic acid-isoxazole (2) derivatives of an antiviral drug analogue WIN 61893 were synthesized and characterized by X-ray crystallography and NMR spectroscopy. Crystallization experiments afforded two polymorphic structures for the ethyl ester derivative and two solvate structures for the carboxylic acid derivative based on their ability to form intermolecular hydrogen bonding interactions with the solvent molecules. The conformations of the derivatives depended greatly on the orientation of the planar isoxazole and phenyl-oxadiazole ring systems with respect to one another and were found to take up perpendicular, linear or tilted conformations. The carboxylic a…

2-Oxoglutarate decarboxylase ofLeuconostoc oenos

1990

InLeuconostoc oenos, the typical organism of the malolactic fermentation of wine, a 2-oxoglutarate decarboxylase was detected. This inducible enzyme decarboxylates 2-oxoglutarate but not pyruvate. The resulting succinaldehydate is rapidly reduced to 4-hydroxybutyrate or oxidized to succinate in further reactions. 2-Oxoglutarate decarboxylase is thiamin-diphosphate-dependent; the pH optimum is at 5.3 and theK m value for 2-oxoglutarate is 1.8 mmol/L.

ChemInform Abstract: Nucleophilic Benzoylation Using Lithiated Methyl Mandelate as a Synthetic Equivalent of the Benzoyl Carbanion. Oxidative Decarbo…

2010

Abstract The synthesis of alkyl aryl ketones using lithiated methyl mandelate as a synthetic equivalent of the benzoyl carbanion is reported (Umpolung). The methodology involves alkylation of methyl mandelate, hydrolysis of the ester group and oxidative decarboxylation of the resulting α-hydroxyacids. The last step is carried out in a catalytic aerobic way using a Co(III) complex in the presence of pivalaldehyde under very mild and advantageous conditions. The procedure is also applied to methyl mandelates substituted on the aromatic ring.