Enantiomerically pure tetrahydro-5-oxo-2-furancarboxylic esters from dialkyl 2-oxoglutarates

Enantiomerically pure tetrahydro-5-oxo-2-furancarboxylic esters can be prepared either by enzymatic resolution of the racemic γ-lactones themselves or by bioreduction with baker's yeast of dialkyl 2-oxoglutarates and subsequent cyclization of the resulting dialkyl 2-hydroxyglutarates. The best results were obtained by the former route, by which the desired compounds were isolated in high enantiomeric excess. Bioreductions were less satisfactory. In fact the hydroxyester intermediates were initially formed as racemic mixtures and their final enantiomeric enrichment was reached by asymmetric destruction, occurring in the bioreaction medium, however at the same time large amounts of alkyl 4-hydroxybutanoates were formed as side products.     

Synthesis of [5'-13C]ribonucleosides and 2'-deoxy[5'-13C]ribonucleosides

The present efficient synthesis of [5'-13C]ribonucleosides and 2'-deoxy[5'-13C]ribonucleosides is characterized by the synthesis of the D-[5-13C]ribose derivative as an intermediate via the Wittig reaction of 4-aldehydo-D-erythrose dialkyl acetals with Ph3P13CH3I-BuLi to introduce the 13C label at the 5-position of a pentose. This was followed by the highly diastereoselective osmium dihydroxylation for the preparation of 2,3-di-O-benzyl-D-[5-13C]ribose dialkyl acetal and the cyclization from D-[5-13C]ribose dialkyl acetal derivatives to the alkyl D-[5-13C]ribofuranoside derivative by the use of LiBF(4). The obtained D-[5-13C]ribose derivative was converted into [5'-13C]ribonucleosides and subsequently into the corresponding 2'-deoxynucleosides.     

Synthesis and Functionalization of 5-Alkyl-6-methyl-2-thiouracils

Russian Journal of General Chemistry - A number of 5-alkyl-6-methyl-2-thiouracils were obtained, the further introduction of which into the reaction with dialkyl chloroethynylphosphonates afforded...     

Vinyltriphenylphosphonium Salt Mediated One-Pot Stereoselective Synthesis of Dialkyl ( E )-2-(2-methyl-5-oxo-1-cyclopentenyl)-2-butenedioates

Protonation of the highly reactive 1:1 intermediates produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates by 2-hydroxy-3-methyl-2-cyclopenten-1-one leads to vinyltriphenylphosphonium salts, which undergo an intramolecular Wittig reaction to produce the corresponding cyclobutene derivatives. The cyclobutene derivatives are not isolable and undergo electrocyclic ring-opening reactions in CH 2 Cl 2 at room temperature to produce dialkyl ( E )-2-(2-methyl-5-oxo-1-cyclopentenyl)-2-butenedioates in moderate yields.     

Analogues of the Quararibea metabolite chiral enolic-γ-lactone from (2S,3S)- and (2S,3R)-tetrahydro-3-hydroxy-5-oxo-2,3-furandicarboxylic acids

Reaction of dialkyl (2S,3S)- or (2S,3R)-tetrahydro-3-hydroxy-5-oxo-2,3-furandicarboxylates with POCl₃ in pyridine followed by diazomethane resulted in the isolation of dialkyl 2S-4-methoxy-5-oxo-2,5-dihydro-2,3-furandicarboxylates, which are analogues of the Quararibea metabolite chiral enolic-γ-lactone (3-hydroxy-4,5-(R)-dimethyl-2(5H)-furanone). An unusual α-hydroxylation of γ-butyrolactone takes place involving POCl₃ in pyridine. When the dehydration was facilitated with methanesulfonyl chloride in triethylamine, instead of POCl₃, aromatic dialkyl 5-[(methylsulfonyl)oxy]-2,3-furandicarboxylates were obtained.     

Synthesis and Antimicrobial Activity of 2-[5-(R-Benzyl)-4-oxo-1,3-thiazolidin-2-ylidene]-3-oxobutanenitrile and [2-(1-Cyano-2-oxopropylidene)-4-oxo-1,3-thiazolidin-5-ylidene]acetic Acid Derivatives

Russian Journal of Organic Chemistry - The reactions of 2-cyano-3-oxobutanethioamide with ethyl 3-aryl-2-bromopropanoates and dialkyl acetylenedicarboxylates afforded a combinatorial library of new...     

Alkylation of 5-nitro-l,2,4-triazol-3-one

The alkylation of 5-nitro-1,2,4-triazol-3-one with dialkyl sulfates and alkyl iodides has given N-alkyl-5-nitro-1,2,4-triazolones. The structure of the compounds obtained has been shown by independent synthesis via the corresponding N-alkyl derivatives of 1,2,4-triazol-3-one.     

Efficient and Simple Route for the Synthesis of N-(2-Pyridyl)-4-ethoxy-5-oxo-2,5-dihydro-1H-pyrrole-2,3-dicarboxylates

Three-component reaction of 2-aminopyridines, dialkyl acetylenedicarboxylates, triphenylphosphine, and ethyl chlorooxoacetate in the presence of triethylamine provides a sufficient route for the synthesis of dialkyl N-(2-pyridyl)-4-ethoxy-5-oxo-2,5-dihydro-1H-pyrrole-2,3-dicarboxylates in good yields.     

Investigation of reactions of the organozinc reagents prepared from zinc and dialkyl dibromomalonates with the derivatives of 2-arylmethyleneindan-1,3-dione and 5-arylmethylene-2,2-dimethyl-1,3-dioxane-4,6-dione

Organozinc compounds prepared from dialkyl dibromomalonates and zinc react with 2-arylmethyl-eneindan-4,6-diones, 5-arylmethylene-2,2-dimethyl-1,3-dioxane-4,6-diones, as well as with 2-[4-(1,3-dioxoindan-2-ylidenemethyl)phenyl]methyleneindan-1,3-dione and 5-[4-(2,2-dimethyl-4,6-dioxo-1,3-dioxane-2-ylidenemethyl)phenyl]methylene-2,2-dimethyl-1,3-dioxane-4,6-diones to form dialkyl 3-aryl-1′3′-dioxaspiro(cyclopropane-2,2′-indan)-1,1-dicarboxylates, dimethyl 3-aryl-6,6-dimethyl-5,7-dioxa-4,8-dioxaspiro[2,5]octan-2,2-dicarboxylates, dialkyl 2-{4-[3,3-bis (alkoxycarbonyl)-1′,3′-dioxaspiro(cyclopropane-2,2′-indan)-1-yl]phenyl}-1′,3′-dioxaspiro[cyclopropane-2,2′-indan]-1,1-dicarboxylates, and dialkyl 2-{4-[2,2-bis(alkoxycarbonyl)-6,6′-dimethyl-4,8-dioxo-5,7-dioxaspiro[2,5]oct-1-yl]phenyl}-6,6-dimethyl-4,8-dioxo-5,7-dioxaspiro[2,5]octan-1,1-dicarboxylate respectively.     

Vinylphosphonium Salt Mediated Facile Synthesis of Trialkyl 4-(2-Quinolyl)-1-cyclobutene-1,2,3-tricarboxylates and Dialkyl 3-Ethoxy-4-oxo-5-(2-(1H)-quinolinylidene)-2-cyclopentene-1,2-dicarboxylates

Summary.  The reactive 1:1 intermediate produced in the reaction between dialkyl acetylenedicarboxylates and triphenylphosphine was trapped by ethyl 3-(1,2-dihydroquinoline-2-ylidene)-pyruvate to yield the isomeric dialkyl 3-ethoxy-4-oxo-5-(2-(1H)-quinolinylidene)-2-cyclopentene-1,2-dicarboxylates and trialkyl 4-(2-quinolyl)-1-cyclobutene-1,2,3-tricarboxylates in nearly 4:1 ratio. Received April 3, 2001. Accepted (revised) May 22, 2001     

Synthesis of Alkyl (5-Oxo-2-thioxo-[1,3,4]thiadiazinan-6-ylidene)acetates by the Reaction of N-Aminorhodanine,Dialkyl Acetylenedicarboxylates,and Triphenylphosphine

Protonation of the reactive zwitterionic intermediate produced from the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates by N-aminorhodanine followed by the addition of the conjugate anion of N-aminorhodanine on the produced vinylphosphonium cation leads to alkyl (5-oxo-2-thioxo-[1,3,4]thiadiazinan-6-ylidene)acetates in good yields.     

A novel copper-catalyzed,one-pot synthesis of symmetric organic disulfides from alkyl and aryl halides: potassium 5-methyl-1,3,4-oxadiazole-2-thiolate as a novel sulfur transfer reagent

A new method is reported for the synthesis of symmetric diaryl and dialkyl disulfides from aryl and alkyl halides in the presence of copper using potassium 5-methyl-1,3,4-oxadiazole-2-thiolate as the base, ligand, and sulfur-transfer reagent.     

One-Pot,Three-Component Synthesis of Dialkyl 1,2-Dihydroquinoline-2,3-Dicarboxylates from Triphenylphosphine,Acetylenic Esters,and Amide Derivatives of 2-Aminobenzaldehyde in Aqueous Acetone

Abstract

Protonation of the highly reactive 1:1 intermediates, produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates by amide derivatives of 2-aminobenzaldehyde in the mixture of acetone-water (3:1) leads to vinyltriphenylphosphonium salts, which undergo a Michael addition reaction with a conjugate base to produce the corresponding stabilized phosphorus ylides. An intramolecular Wittig reaction of the stabilized phosphorus ylide group with the aldehyde group leads to the corresponding dialkyl 1,2-dihydroquinoline-2,3-dicarboxylates.     

An Efficient,One-Pot Synthesis of Dialkyl 5-Hydroxy-4-aryl-2,5-dihydrofuran-2,3-dicarboxylate Derivatives

The reaction between arylglyoxalmonohydrates, dialkyl acetylenedicarboxylates, and triphenylphosphine is described as a simple and efficient method for the synthesis of 5-hydroxy-4-aryl-2,5-dihydrofuran-2,3-dicarboxylate derivatives.     

HIGHLY STEREOSELECTIVE SYNTHESIS OF DIALKYL 2-ALKYLIDENE GLUTARATES

Nucleophelic substitution of dialkyl (E)-2-bromomethylene glutarates 2 by magnesium dialkyl cuprates generated in situ provided a regio and highly stereoselective methodology for the synthesis of dialkyl 2-alkylidene glutarates 3 in good yields.     

Structure of 2(5)-alkyl-4-hydroxy-3,4-diphenylcyclopent-2-en-1-ones,cyclocondensation products of benzil with aliphatic ketones

The reaction of benzil with methyl alkyl ketones gave three isomeric cyclopentenone derivatives, 2-substituted and cis- and trans-5-substituted 4-hydroxy-3,4-diphenylcyclopent-2-en-1-ones. cis- and trans-2,5-Disubstituted 4-hydroxy-3,4-diphenylcyclopent-2-en-1-ones were formed in analogous reaction of benzil with dialkyl ketones. The structure of the products was confirmed by ¹H NMR spectroscopy and molecularmechanics calculations.     

Synthesis of New Polysubstituted Indolizines from Pyridine,Bromonitromethane, and Dialkyl Acetylenedicarboxylates

An efficient and novel approach to the synthesis of dialkyl 1‐nitroindolizine‐2,3‐dicarboxylates has been described. A one‐pot reaction between a pyridine, dialkyl acetylendicarboxylate, and bromonitromethane leads to dialkyl 1‐nitroindolizine‐2,3‐dicarboxylates in good yields.     

Intramolecular cyclization of dialkyl[2-(5-chloro-2-hydroxyphenyl)-2-phenylethenyl]phosphine oxides by the action of thionyl chloride

An efficient procedure has been proposed for the synthesis of quasiphosphonium salts, 2,2-dialkyl-6-chloro-4-phenyl-2H-1,2-benzoxaphosphinin-2-onium chlorides, via cyclization of dialkyl[2-(5-chloro-2-hydroxyphenyl)-2-phenylethenyl]phosphine oxides under the action of thionyl chloride.     

A facile route to diastereomeric phosphorus ylides. Chemoselective synthesis of dialkyl (E)-2-[1-(2-oxocyclopentylidene)ethyl]-2-butenedioates

2-Acetylcyclopentanone undergoes a smooth reaction with triphenylphosphine and dialkyl acetylenedicarboxylates to produce dialkyl 2-(1-acetyl-2-oxocyclopentyl)-3-(1,1,1-triphenyl-lambda(5)-phosphanylidene)succinates. These compounds undergo intramolecular Wittig reactions in boiling benzene to produce highly strained spirocyclobutene derivatives, which spontaneously undergo ring-opening reactions to produce dialkyl (E)-2-[1-(2-oxocyclopentyliden)ethyl]-2-butenedioates.     

Reaction between tert-butyl isocyanide, dialkyl acetylenedicarboxylates, and aromatic carboxylic acids: an efficient method for the synthesis of dialkyl (E)-2-{[benzoyl(tert-butyl)amino]carbonyl}-2-butenedioate derivatives

Protonation of the reactive intermediates produced in the reaction between tert-butyl isocyanide and dialkyl acetylenedicarboxylates by aromatic carboxylic acids leads to vinylnitrilium cations, which undergo nucleophilic reaction with conjugate bases of the carboxylic acids to produce dialkyl (E)-2-[(benzoyloxy)(tert-butylimino)methyl]-2-butenedioates and this intermediate rearranges to the dialkyl (E)-2-{[benzoyl(tert-butyl)amino]carbonyl}-2-butenedioate derivatives.