TMSI-Promoted Diastereoselective Synthesis of 5-(1′-Hydroxy)-γ-butyrolactones

Trimethylsilyl iodide (TMSI) was found to be an efficient catalyst for the vinylogous Mukaiyama aldol reaction of 2-(trimethylsilyloxy)furan with various aldehydes with good diastereoselection. The reaction proceeds rapidly in CH₂Cl₂ affording the corresponding 5-(hydroxy(aryl)methyl)furan-2(5H)-ones in good yields. This method offers significant advantages such as efficiency, generality, and mild reaction conditions with shorter reaction time.

A Facile Synthesis of 5-(2′-Oxoalkyl)-2-Cyclopenten-1-Ones

In spite of the fact that a number of methods are available for the preparation of C-5-monoalkylated (simple alkyl) cyclopentenones¹, general synthetic routes leading to cyclopentenones possessing an activated side chain at C-5 remain virtually unknown². In connection with our synthetic studies on iridoids³, we have developed a convenient synthesis of the title compounds which we wish to report herein.     

Synthesis of Guanosine 5′-(β-L-Fucopyranosyl)-Diphosphate Revisited

ABSTRACT

It will be demonstrated that a successful synthesis of β-L-fucopyranose-1-phosphate (2), a key intermediate in the preparation of guanosine 5′-(β-L-fucopyranose)-diphosphate (1), strongly depends on the nature of the acyl protecting groups for the non-anomeric hydroxyl functions. Thus, the perbenzoylated, instead of peracetylated, α-L-fucopyranosyl trichloroacetimidate (11) or the corresponding ethyl β-thiofucopyranoside proved to be a convenient starting compound for the preparation of 2. Further, condensation of N,N′-dicyclohexyl-4-morpholinecarboxamidinium guanosine 5′-morpholidophosphate with excess 2 gave the title compound without concomitant formation of bisguanosine-5′-diphosphate (16).     

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 and Crystal Structure of 4-Phenyl-5-(1′- t-butyl-5′-methyl-4′-pyrazolyl)-1,2,4-triazol-3-thione

The crystal structure of 4-phenyl-5-(1′-t-butyl-5′-methyl-4′-pyrazolyl)-1,2,4-triazol- 3-thione 5 (C16H19N5S, Mr = 313.42) has been determined by single-crystal X-ray diffraction analysis. The crystal belongs to monoclinic, space group P21/c with a = 6.680(2), b = 27.44(1), c = 9.388(4)(A。), β = 106.738(6)°, V = 1648(1)(A。)3, Z = 4, Dc = 1.263 g/cm3, μ= 0.200 mm-1, F(000) = 664, R = 0.0608 and wR = 0.1176. The results confirmed that 5 can be assigned to the thione tautomeric form.     

A Facile Synthesis of an Advanced Glycosylation Endproduct 2-(2′-furoyl)-4(5)-(2′-furanyl)-1H-imidazole

Abstract: A three step synthesis of the advanced glycosylation endproduct 2-(2′-furoyl)-4(5)-(2′-furanyl)-1H-imidazole (4, FFI) has been achieved from 2-acetylfuran. The key step in the synthesis was the rearrangement of the hydrazinium bromide 3 in refluxing methanol.     

Stereoselective Synthesis and Characterization of (Z)-(−)-4-(1′-Alkoxyl-1′-alkyloxycarbonyl-methylidene)-5(R)-[(1R)-menthyloxy]-γ-butyrolactones

Abstract

A series of enantiomerically pure (Z)-(?)-4-(1′-alkyloxy-1′-alkyloxycarbonyl-methylidene)-5(R)-[(1R)-menthyloxy]-γ-butyrolactones were synthesized and characterized in good to excellent yields via O-alkylation of (4R,5R)-(?)-4-ethoxyoxalyl-5-[(1R)-menthyloxy]-γ-butyrolactone with alkyl halides in the presence of K₂CO₃ in acetone at room temperature.     

Convenient Synthesis of Uridine 5′ - Oxyphosphorane

Uridine 5′-oxyphosphorane was synthesized by the reaction of 2′, 3′-di-O-acteyluridine 5′-diisopropyl phosphite with tetrachloro-1, 2-benzoquinone.     

Synthesis and Crystal Structure of 1-[(1′-Phenyl-5′-methyl-4′-pyrazolcarbonyl)- 3-methylthio-5-amino-1H-yl-1,2,4-triazole

1INTRODUCTIONTheCIDT(N-cyanoimido-S,S-dimethylthiocarbo-nate)hasbeenwidelyutilizedinorganicsynthesisduringthelasttwodecadesandhasbecomeveryusefulforconstructingfunctionalizedheterocyliccom-poundsbecauseoftheirversatility.MuchattentionhasrecentlybeenfocusedonthedevelopmentofCIDTaswellastheirsyntheticapplications[1～4].Meanwhile,manypyrazoleandtriazolederivativesarereportedtoshowvariousbiologicalactivities,suchasantifungal[5],herbicidal[6～8],insectcidal[9]andotheractivities[10～12].Thu…     

Synthesis and Characterization of 4′-Bromomethyl-2-(N-trityl-1H-tetrazol-5-yl) Biphenyl

Biphenyl tetrazole ring is an important component of the Sartan family of novel drugs. 4′-Bromomethyl-2-(N-trityl-1H-tetrazol-5-yl)biphenyl was synthesized in this article from 4′-methyl-2-cyano-biphenyl through three steps. 4′-Methyl-2-cyano-biphenyl was reacted with azide ions with the help of ammonium chloride as catalyst in an autoclave with high conversion to afford the tetrazole compounds in 70.6% yield. After being protected by the trityl group with 92.6% yield, 4′-methyl-2-(N-trityl-1H-tetrazol-5-yl) biphenyl was brominated with N-bromosuccinimide (NBS) in cyclohexane with 2,2′-azo-isobutyronitrile (AIBN) acting as an initiator to provide the title compound in 83.8% yield.     

Synthesis of 4,4′-(arylmethylene)bis(3-methyl-1H-pyrazol-5-ol) derivatives in water

An environmentally friendly and simple method for the synthesis of some 4,4′-(arylmethylene)bis(3-methyl-1H-pyrazol-5-ol) derivatives via a one-pot pseudo five-component reaction of hydrazine hydrate, ethyl acetoacetate and aldehydes in water using pyridine trifluoroacetate or acetic acid at 70 °C is reported.     

Synthesis of (±)-10H-Phenothiazine-10-propanoyl-1′-myo-inositol

The synthesis of (±)10H-phenothiazine-10-propanoyl-1′-myo-inositol was accomplished in order to test it as inhibitor of phosphatidylinositol specfic phospholipase C (PI-PLC).     

Synthetic Applications of Stereodefined 2-Substituted 1-Silyl-1-stannylethenes: A New Synthesis of 5-Ethenyl-5′-(1-propynyl)-2,2′-bithiophene,a Naturally-Occurring Phototoxin)

(E)-2-(5-Trimenthylstannyl-2-thienyl)ethenyldimethylphenylsilane. (E)-8, which can be stereospecifically prepared from (Z)-1-dimethylphenylsilyl-2-(2-thienyl)-1-trimethylstannyl-ethene, (Z)-6, or from (E)-2-(2-thienyl)ethenyldimethylphenylsilane, (E)-9, serves as an equivalent to the 2-ethenylthiophene d ¹', d ⁵-synthon, 20, in an efficient two-step synthesis of 5-ethenyl-5′-(1-propynyl)-2,2′-bithiophene, 10, a naturally-occurring phototoxin. In the first step of this synthesis compound (E)-8 undergoes a palladium-catalyzed cross-coupling reaction with 2-iodo-5-(1-propynyl)thiophene, 16, and in th second step the so obtained cross-coupling product, (E)-17, undergoes a protodesilylation reaction.     

Synthesis of E-3-Hydroxymethyl-1-methoxy-4-(1′-pentenyl)benzene

The title compound with exclusively the E-geometry has been synthesized by two independent routes. When this compound was reacted with cerium (IV) ammonium nitrate, it was found that oxidative cyclisation to the corresponding 4-hydroxybenzo-pyrans did not occur. This further defines the structural parameters required for such oxidative cyclisations.     

Photochemical and Picric Acid-Catalyzed Isomerization of 4-(4′-Dimethylaminostyryl)pyridine

Equilibrium photoisomerization of trans-DASP into cis-DASP occurs in a solution. In presence of picric and trifluoroacetic acids in acetonitrile, cis-DASP isomerizes into trans-DASPH⁺ cation. The reaction is inhibited by three molecules of PicOH. Acid-catalyzed mechanism of isomerization is confirmed by semiempirical calculation (PM3) of changes in standard heats of the separate steps.     

Microwave-accelerated Synthesis of Some (±)-1-Aryl-5-chloroisochromans

Solventless one-pot synthesis of some new (±)-1-aryl-5-chloroisochromans by cyclocondensation of 2-(2-chlorophenyl)ethanol with aromatic aldehydes via an acid catalyzed oxa-Pictet-Spengler reaction under microwave irradiation is described.     

Facile Synthesis of 2-(4-Hydroxybiphenyl-3-yl)-1H-indoles from Anilines and 5′-Bromo-2′-hydroxyacetophenone

2-Arylindoles are attractive scaffolds because they are found in many pharmacologically active molecules. In this study, we describe the facile synthesis of diverse 2-(2-hydroxyphenyl)-1H-indoles from anilines and 5′-bromo-2′-hydroxyacetophenone in two steps using palladium-catalyzed indole cyclization as a key reaction. The indole cyclization was primarily controlled by the substituent properties of anilines. Suzuki-coupling reactions of 2-(5′-bromo-2′-hydroxyphenyl)-1H-indoles with arylboronic acids provided the corresponding 2-(4-hydroxybiphenyl-3-yl)-1H-indoles in moderate yield.     

Synthesis and Crystal Structure of 5-N-i-Propyl-2-(2′-nitrobenzenesulfonyl)-glutamine

IntroductionAcetohydroxy acid synthase(AHAS) is a perfecttarget for the design of environmentally benign herbi-cides because it is a key enzyme that is absent in ani-mals but is important for the biosynthesis of branched-chain amino acids in plants[1,2]. …     

Ionic-Liquid Salt-Mediated Synthesis of 4′-(Pyridyl)-terpyridines

One-pot reactions to produce isomeric 4′-(pyridyl) 2,2′:6′,2″-terpyridine under moderate conditions are described using imidazolium-based ionic liquid and quaternary ammonium-based molten salts as solvent media. The use of eutectic molten salts as a reaction media proved effective in sequential aldol and Michael addition reactions, leading to substituted terpyridines. The desired product was obtained in reasonable yield via a simple, one-pot reaction.