Transformations of β-d-xylofuranosyl nucleosides. Synthesis of 3′-azido-3′-deoxythymidine

A modified synthesis of 3′-azido-3′-deoxythymidine starting fromD-xylose is proposed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2062–2063, October, 1998.     

Synthesis of β-D-xylofuranosyl- and 2,2′-anhydro-1-β-D-lyxofuranosylpyrimidine nucleosides

-D-Xylofuranosylpyrimidines were obtained by condensation of silyl derivatives of pyrimidines with 1,2-di-O-acetyl-3,5-di-O-benzoyl-D-xylofuranose with subsequent deprotection of the sugar fragment. Refluxing 2-O-tosyl derivatives of nucleosides with NaI results in the formation of 2,2-anhydro-compounds.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1137–1141, June, 1993.     

First Stereqselective Synthesis of Nitrophenyl 2-Deoxy- β-D-glycosides

α-Dithiophosphates of peracetylated 2-deoxyhexc-pyranoses, 1a, 1b and 2, uhich are easily prepared by addition of organic phosphorodithioic acids to glycais react smoothly with resin-bound 2- and 4-nitrophenoxides to give stereoselectively the respective nitrophenyl 2-deoxy-β-D-hexopyranosides (3, 4, 5 and 6) in high yields. Glycosylation of the 2, 4-dinitro'phenoxide, however, leads with comparable stereoselectivity to 2,4-dinitrophenyl 2-deoxy- α-D-hexopyranosides (7 and 8).

Glycosides 3 - 6 are quantitatively deacetylatec by Amberlyst A-26 (OH^-), whereas glycosides 7 and 8, under the same reaction conditions undergo splitting of the O-glycosidic bond.     

Facile and Efficient One-Pot Synthesis of β-Carbolines

Initial formation of tetrahydrocarboline 3 from tryptophan methyl ester 1 and aldehyde 2 by Pictet–Spengler reaction, followed by treatment with trichlorocyanuric acid, provides a facile and efficient route for a one-pot synthesis of β-carbolines with excellent yields.     

Synthesis of 4,4′-Oxydibenzoic Acid Amides and Sulfonamides Containing 2-Arylaminopyrimidine Moieties

Russian Journal of Organic Chemistry - New 4,4′-oxydibenzamides and sulfamoyl derivatives of 4,4′-oxydibenzoic acid containing pharmacophoric 2-arylaminopyrimidine fragments in the...     

Efficient synthesis of fluorinated α- and β-amino nitriles from fluoroalkylated α,β-unsaturated imines

A simple and efficient synthesis of fluoroalkylated α-amino nitrile (4) derivatives by regioselective 1,2-addition of trimethylsilyl cyanide to fluoroalkylated α,β-unsaturated imines (1) is described. Fluoroalkylated β-amino nitriles (7) are also prepared by regioselective 1,2-addition of α-carbanions derived from acetonitrile to fluoroalkylated α,β-unsaturated imines (1). Fluoroalkylated α-(4) and β-amino nitriles (7) are also prepared through an ‘one pot’ procedure by reaction of enaminophosphonate 2 with BuLi, addition of aldehydes and subsequent addition of either trimethylsilyl cyanide or α-carbanion derived from acetonitrile. Basic hydrolysis of α-(4) and β-amino nitriles (7) gives fluoroalkylated α-(5) and β-amino acids (8).     

Efficient Synthesis of 1-Deaza-6-methoxypurine-N9-β-2′-deoxyribonucleoside and Related DNA Building Blocks

An improved synthesis of the 2′-deoxyribonucleoside containing 1-deaza-6-methoxypurine as artificial nucleobase is described. By optimizing the conditions for the deprotection of p-toluoyl-protected 1-deaza-6-nitropurine 2′-deoxyribonucleoside, the isolated yield of the title compound could be increased from 15% to 90%. In addition, the synthesis and characterization of the corresponding 5′-(4,4′-dimethoxytrityl) (DMT) protected phosphoramidite, a potentially useful building block for the synthesis of artificial oligonucleotides, is reported. The title compound offers interesting hydrogen bond donor and metal-binding properties for its application in metal-mediated base pairs.

Synthesis with organoboranes. 21. Synthesis of α- and gd-bamascone

Selective syntheses of α- and gd-damascone, using allylic organoboranes as the key intermediates, are described.     

Synthesis of 2-oxazolones and α-aminoketones via palladium-catalyzed reaction of β,β-dibromoenamides

β,β-Dibromoenamides show two different interesting reactivities based on the choice of R group under the reaction conditions. On the basis of mechanistic studies, both reactions proceed via an intermolecular Suzuki-Miyaura C-C coupling and an intramolecular C-O coupling.     

Synthesis of α-trifluoromethyl-phenethylamines from α-trifluoromethyl β-aryl enamines and β-chloro-β-(trifluoromethyl)styrenes

A novel synthetic approach towards α-trifluoromethyl-phenethylamines was elaborated by reduction of the electron deficient β-aryl-α-trifluoromethyl enamines and imines with sodium cyanoborohydride in the presence of trifluoroacetic acid. The starting imines were prepared by the reaction of primary amines with β-aryl-α-trifluoromethyl enamines or β-chloro-β-(trifluoromethyl)styrenes.     

Synthesis of β-L-2′,3′-Dideoxy-2′-fluoro-3′-hydroxymethylarabinofuranosyl Pyrimidine Nucleosides

β-2′,3′-Dideoxy-2′-fluoro-3′-hydroxymethylarabinofuranosylthymine 10 and cytosine 12 were synthesized from L-xylose and were found to be inactive against HIV-1 in acutely infected lymphocytes.     

Facile and Efficient Regioselective Synthesis of 1-(3′-Substituted Quinoxalin-2′-yl)-3-aryl/heteroaryl-5-methylpyrazoles

This report describes an efficient and practical approach for regioselective synthesis of 1-(3′-substituted quinoxalin-2′-yl)-3-aryl/heteroaryl-5-methylpyrazoles (3a–j). Reaction of 2-chloro-3-substituted quinoxalines (1) with 3(5)-methyl-5(3)-aryl-1H-pyrazoles (2) in the presence of sodium hydride furnished the title compounds in excellent yields with good levels of regioselectivity. The present protocol is superior to the existing method, which yielded a mixture of regioisomeric pyrazoles (I, II) and triazolo[4,3-a]quinoxalines (III).

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Efficient method for the asymmetric reduction of α- and β-ketophosphonates

An efficient and versatile method for the asymmetric reduction of α- and β-ketophosphonates using chiral reactant derived from sodium borohydride and l-(+)- or d-(−)-tartaric acid is developed. The methodology was used for the preparation of a number of biologically interesting enantiomerically pure products: including 2,3-epoxypropylphosphonate 11, 2-hydroxy-3-aminopropylphosphonic acid 14 (phospho-GABOB), phospho-carnitine 19, and others in multigram scale.     

Reaction of α-Halo-Enones with Heterocyclic Bases. A Mild and Efficient Synthesis of Amino-Steroids

A number of steroids containing cyclic amino functions have been prepared and studied for biological activities, and some of them have proved to be clinically useful as a neuromuscular blocking agent, an antitumour agent, and so on.¹ As the conventional methods, the reactions of cyclic amines with halides² or epoxides,³ the reductive amination of ketones,⁴ and the reduction of enamines⁵ have been widely used for introducing these amino functions into steroid nucleus.     

Crystal structures of α- and β-EuPrCuS3

The crystal structure of the EuPrCuS₃ complex sulfide synthesized for the first time has been solved by X-ray powder diffraction. Crystals are orthorhombic, space group Pnma. EuPrCuS₃ has two polymorphs: the high-temperature phase of Ba₂MnS₃ structural type with unit cell parameters a = 8.0786(1) Å, b = 4.0288(1) Å, and c = 15.8389(2) Å and the low-temperature phase of BaLaCuS₃-isostructural with unit cell parameters a = 11.0819(2) Å, b = 4.0710(1) Å, and c = 11.4459(3) Å.     

Synthesis of 2′-5′,3′-5′ linked triadenylates

2′-5′,3′-5′ Linked triadenylates have been synthesized by direct bisadenylylation of adenosine 2′ and 3′ hydroxyls with an adenosine 5′-phosphorochloridite followed by oxidation.     

Synthesis of 2′-C-Methyl Ribonucleoside Analogues with Modified Heterocyclic Base Moieties

Recently, 2′-C-methyl nucleoside analogues have been reported to exhibit potent anti–hepatitis C virus (HCV) activity through inhibition of HCV RNA replication without significant cytotoxicity. As a part of our continuous efforts of searching for novel antiviral agents, we now report the synthesis of heterobase-modified 2′-C-methyl ribonucleoside analogues.     

The Reaction of β-Aminoenones with Cyanamide. A High Efficient Synthesis of 2-Aminopyrimidines

β-aminoenones react with cyanamide, molar ratio 1:2, to yield 2-aminopyrimidines in nearly quantitative yields.     

Synthesis and properties of α, α′ -bis -(p-benzylphenyl)xylene

Summary ,-bis-(p-Benzylphenyl)xylene was synthesized for the first time and its UV and infrared spectra determined.