Regioselective ring opening of β-phenylglycidate and aziridine-2-carboxylates with N-alkylhydroxylamines: synthesis of isoxazolidinones

A simple and efficient method for the synthesis of 4-hydroxy or 4-alkylamino isoxazolidin-3-ones and 4-hydroxy isoxazolidin-5-ones is described. The synthesis involved the ring opening of ethyl β-arylglycidates or ethyl N-alkylaziridine-2-carboxylates by free N-alkylhydroxylamines or hydroxylamine anions, followed by cyclization to give the title isoxazolidinones in moderate to good yields.     

Rongalite promoted highly regioselective synthesis of β-hydroxy sulfides by ring opening of epoxides with disulfides

Rongalite^® promotes cleavage of disulfides generating thiolate anions that then undergo facile ring opening of epoxides in the presence of K₂CO₃ to afford α-addition products 3 with good to excellent yields. The important features of this methodology are broad substrates scope, high yielding, reasonably rapid reaction rate, high regioselectivity and no requirement of metal catalysts. It should be noted that the thiolate anion attacks the epoxides derived from styrene to produce the corresponding α-addition products 3 with high regioselectivity, instead of the β-addition regioisomer 4 that could be formed from the attack of the nucleophile at the benzylic position.     

Synthesis of enantiopure β2-homoalanine derivatives via rhodium catalyzed asymmetric hydrogenation

The stereoselective synthesis of chiral β²-homoalanine derivatives with 99% ee by the Rh-catalyzed enantioselective hydrogenation of prochiral 2-aminomethyl acrylates is described. The subsequent transformation to chiral 3-amino-2-methylpropanols is also demonstrated.     

Synthesis of (+)-disparlure from diethyl (−)-malate via opening and fragmentation of the three-membered ring in tertiary cyclopropanols

(+)-Disparlure [(7R,8S)-7,8-epoxy-2-methyloctadecane, pheromone of the gypsy moth Lymantria dispar L.] was synthesized starting from diethyl (?)-malate via cyclopropanation of the ester groups, selective protection of the 1,3-diol functionality, and successive opening and fragmentation of the three-membered rings in the corresponding tertiary cyclopropanols as key stages.     

Efficient synthesis of β-amino alcohols by regioselective ring opening of epoxides with amines catalyzed by CuFe2O4 nanoparticles

A simple and efficient method has been developed for the synthesis of β-amino alcohols by regioselective ring opening of epoxides with amines in the presence of CuFe₂O₄ nanoparticles as a heterogeneous recyclable catalyst at room temperature in high yields.     

Studies on the synthesis of orthogonally protected azalanthionines,and of routes towards β-methyl azalanthionines,by ring opening of N-activated aziridine-2-carboxylates

Orthogonally protected azalanthionines were successfully synthesised by the ring-opening of N-activated aziridine-2-carboxylates with protected diaminopropanoic acids (DAPs). The required DAPs were also prepared by ring-opening of N-activated aziridine-2-carboxylates with para-methoxybenzylamine, but it was found that the choice of aziridine protecting groups dictated both the success of the reaction as well as the regioselectivity of the isolated products. Attempts to extend the methodology to the preparation of the more sterically demanding β-methyl azalanthionines have, so far, been unsuccessful.     

Advanced procedure for the enzymatic ring opening of unsaturated alicyclic β-lactams

Enantiopure β-amino acids 1a–4a and β-lactams 1b–4b were prepared simultaneously through the lipolase-catalysed enantioselective ring opening of unsaturated racemic β-lactams (±)-1-(±)-4. High enantioselectivities (E>200) were observed when the reactions were performed with 1 equiv of water in iPr₂O at 70 °C. The resolved (1R,2S)-amino acids (yield⩾45%) and (1S,5R)-, (1S,6R)- and (1S,8R)-lactams (yield⩾47%) could be easily separated. The ring opening of lactam enantiomers 1b–4b with 18% HCl afforded the corresponding β-amino acid hydrochlorides 1c·HCl–4c·HCl (ee >95%).     

Synthesis of β-nitramino derivatives ofgem-dinitroalkanes

A method for the synthesis of β-nitramino derivatives ofgem-dinitroalkanes by nitration of the products of condensation of sulfamic acid derivatives with the correspondinggem-dinitroalkanes was proposed.     

Synthesis of β-D-xylopyranoside thiophosphate derivatives

A method of synthesis of β-D-xylopyranoside thiophosphate derivatives was developed. Biological testing revealed a high insecticidal activity in the synthesized compounds.     

Synthesis of monocationic β-cyclodextrin derivatives

Russian Journal of Organic Chemistry - Reactions of 6-bromo- and 6-iodo-6-deoxy-β-cyclodextrin with organic amines of diverse nature afforded a series of monocationic derivatives with aminium...     

Synthesis of fluoroalkyl-containing β-hydroxyketones by reduction of the corresponding β-diketone derivatives

The rcgioselective synthesis of fluoroalkyl-containing P-hydroxyketones by the reduction of the salts of the corresponding -diketones with LiAlH₄ was proposed. This is the sole method for the synthesis of -hydroxyketones with two fluoroalkyl substituents.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1493–1495, June, 1996.     

Efficient and facile strategy to substituted 2-aminothiazoles via ring opening of α-nitroepoxides

A novel and efficient reaction has been developed to synthesize a set of substituted 2-aminothiazoles from α-nitroepoxides and ammonium thiocyanate. This reaction could proceed smoothly at mild condition, to afford products for a wide range of substrates with good to excellent yields. A possible mechanism has also been proposed.     

Synthesis of substituted α-tetralones and substituted 1-naphthols via regioselective ring expansion of 1-acyl-1-indanol skeleton

Substituted 1-acyl-1-indanols were prepared using the corresponding readily commercially available substituted indanones as starting materials. Treatment of each 1-acyl-1-indanol derivative with sodium methoxide in hot methanol furnished a regiospecific 2-hydroxy-α-tetralone derivative, which was an α-keto rearrangement product. Each substituted 2-hydroxy-α-tetralone then underwent dehydration to afford the corresponding 1-naphthol derivative.     

A three-component one-pot synthesis of penta-substituted pyrroles via ring opening of α-nitroepoxides

A novel and facile one-pot reaction has been developed to synthesize a variety of penta-substituted pyrroles from α-nitroepoxides, primary amines and dialkyl acetylenedicarboxylates under the conditions without catalyst. Furthermore, the controlled experiments has been performed and a possible mechanism has also been proposed.     

Synthesis of 2-hydroxy-5,6-diarylnicotinonitriles and 2-chloro-5,6-diarylnicotinonitriles from β-chloroenones

Vilsmeier–Haack reaction of β-ketoaldehydes leads to the formation of β-chloroenones and these chloroenones on treatment with malononitrile afford 2-hydroxy-5,6-diarylnicotinonitriles. But a one-pot reaction of β-ketoaldehydes with Vilsmeier–Haack reagent and malononitrile or cyanoacetamide results in the formation of 2-chloro-5,6-diarylnicotinonitriles in good yields.     

Synthesis of β-amino acid derivatives via copper-catalyzed asymmetric 1,4-reduction of β-(acylamino)acrylates

A new set of reaction conditions has been established to facilitate the copper-catalyzed enantioselective 1,4-reduction of β-(acylamino)acrylates toward a selection of β-alkyl-β-amino acid derivatives in high yields and with uniformly high ee values (up to 99%) irrespective of the use of (E)- or (Z)-substrates.     

Synthesis of furan derivatives of cyclic β-amino acid cispentacin via intramolecular nitrile oxide cycloaddition

Two furan derivatives of cispentacin have been synthesized starting from a d-mannitol derived conjugated nitroolefin through intramolecular nitrile oxide cycloaddition (INOC) as a key step.     

Synthesis and antiviral bioactivities of novel chiral bis-thiourea-type derivatives containing α-aminophosphonate moiety

Starting from 1-((1R,2R)-2-aminocyclohexyl)-3-substituted thioureas (3a–c) and substituted isothiocyanates (9a–d),chiral bis-thiourea derivatives containing α-aminophosphonate moiety 10a–l were prepared and completely characterized by elemental analysis,physical and spectral (IR,1H NMR,13C NMR,31P NMR) data.The results of bioassay revealed that compounds 10a and 10e possessed appreciable curative bioactivities on cucumber mosaic virus (CMV) at 0.5 mg/mL in vivo (inhibitory rate = 60.3%,64.8% respectively) a...     

Synthesis ofα-substitutedα-amino acids by the alkylation of 5-oxazolinone derivatives

Methods have been developed for the alkylation of 5-oxazolinone derivatives in DMF in the presence of K₂CO₃, KOH, or diisopropylethylamine and a phase transfer catalyst as well as for the preparation of-methyl-phenylalanine,-methylalanine,-methylalanine, and the methyl ester of N-benzoyl--methylalanine. Increasing the initial concentration of the starting 5-oxazolinone in the reaction mixture leads to a sharp drop in the yield of reaction products due to side condensation reactions. The reaction of 2-phenyl-4-benzyl-5- oxazolinone with ethyl iodide gave a dimer namely, 3-(benzoylamino)-3,5-dibenzylpyrrolidine-2,4-dione.Latvian Institute of Organic Chemistry, LV-1006 Riga. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 829–833, June, 1994. Original article submitted January 21, 1994.     

Synthesis of novel zerumbone derivatives via regioselective palladium catalyzed decarboxylative coupling reaction: a new class of α-glucosidase inhibitors

A new strategy for the synthesis of novel zerumbone derivatives via a regioselective palladium catalyzed decarboxylative coupling reaction using arene carboxylic acids is described. The current methodology involves the repositioning of endocyclic double bond to exocyclic double bond of zerumbone. Preliminary in vitro analysis revealed that most of the newly synthesized derivatives are potent α-glucosidase enzyme inhibitors.