A convenient one-pot synthesis of substituted 2-pyrone derivatives

2-Pyrone derivatives were prepared in a one step procedure from readily available (chlorocarbonyl)phenyl ketene and 1,3-diketones such as 2,4-pentanedione, 1,3-diphenyl-1,3-propanedione, 1-phenyl-1,3-butanedione, 1,3-cyclohexanedione, 5,5-dimethyl-1,3-cyclohexanedione, 1,3-dimethyl-pyrimidine-2,4,6-trione and ethyl 2,4-dioxopentanoate. A mechanism is presented to account for the formation of the products. This method provides an easy route to prepare 3,4,5,6-tetrasubstituted 2-pyrones in good to excellent yields and in a short experimental time.     

Facile synthesis and regioselective thio-Claisen rearrangements of 5-prop-2-ynyl/enyl-sulfanyl pyrimidinones: transformation to thienopyrimidinones

A successful generation and utilization of prop-2-ynyl/enyl-sulfanyl ketene in the synthesis of previously unknown pyrimidinones and their thio-Claisen rearrangements leading to thienopyrimidinones is described.     

A convenient one-pot synthesis of homoallylic halides and 1,3-butadienes

An efficient one-pot synthetic pathway for the preparation of homoallylic halides by in situ generated MgBrCl-promoted ring opening of cyclopropylcarbinyl acetates has been established. An easily accessible one-pot synthetic protocol of 1,3-butadienes by the elimination of hydrogen halides from the resulting homoallylic halides in the presence of an excess amount of strong base has also been developed.     

The electronic states of buta-1,3-diene studied by ab initio configuration interaction and DFT methods,and electron energy loss spectroscopy

The electronic vertical excitation energies for singlet and triplet valence, and Rydberg states of trans-buta-1,3-diene have been computed using ab initio multi-reference multi-root CI procedures with a [4s3p3d3f] set of Rydberg functions. Close numerical agreement between theory and experiment was found for a number of low-lying electronic states.     

A convenient synthesis of 5-fluorofuran-2-carboxylic acid

A convenient synthesis of 5-fluorofuran-2-carboxylic acid has been achieved in two steps and 56% total yield. Fluorodenitration of commercially available benzyl 5-nitrofuran-2-carboxylate utilizing potassium fluoride and catalytic tetraphenylphosphonium bromide in sulfolane at 140 °C for 2 h furnished benzyl 5-fluorofuran-2-carboxylate. Hydrogenolysis of benzyl 5-fluorofuran-2-carboxylate gave the title compound.     

A convenient synthesis of phosphonothioic acids

A method for the convenient synthesis of phosphonothioates, or phosphonothioic acids, is reported. A significant advantage of the method is the alleviation of the need for purification of intermediates, other than washing with water. No chromatography is needed and the only purification step is the crystallization of the final product. The method uses standard reagents and should be applicable to the synthesis of phosphonothioic acids bearing a range of functional groups.     

A method for the synthesis of cyclopropanes by regiospecific and regioselective magnesium carbenoid 1,3-CH insertion as the key reactions

Addition reaction of two geometrical isomers of 1-chlorovinyl p-tolyl sulfoxides, derived from unsymmetrical ketones and chloromethyl p-tolyl sulfoxide, with lithium enolate of tert-butyl acetate gave single diastereomers of the adduct, respectively. Treatment of each diastereomer with i-PrMgCl resulted in the formation of magnesium carbenoid. Highly regiospecific 1,3-CH insertion reaction was found to take place from each magnesium carbenoid to afford cyclopropanes. On the other hand, when the unsymmetrical ketones bearing an oxygen- or a nitrogen-functional group on the α-carbon were used in this procedure, the regioselective 1,3-CH insertion reaction proceeded mainly. Stereochemistry of the adducts, reaction mechanism, and essence of the specificity and the selectivity are discussed.     

Partially fluorinated naphthalene derivatives from 1,4-dilithio-1,3-dienes and C6F6

Multi-substituted partially fluorinated aromatic compounds, such as naphthalene derivatives could be readily prepared by the reaction of 1,4-dilithio-1,3-dienes with hexafluorobenzene via double nucleophilic substitution. When these dilithium reagents were treated with hexachlorobenzene, chloropentafluorobenzene or bromopentafluorobenzene, chlorine-lithium or bromine-lithium exchange reactions, instead of nucleophilic substitution, took place.     

A convenient synthesis of 2-nitroindoles

The reaction of 2-iodo- and 2-bromoindoles with silver nitrite in aqueous acetone affords the corresponding 2-nitroindoles in modest to good yields.     

Syntheses,structure, and reactivity of acyclic enetriyne and enetetrayne derivatives

Sonogashira coupling of buta-1,3-diynylbenzene with ((2-iodophenyl)ethynyl)trimethylsilane and 1,2-diiodobenzene led to the novel enetriyne, 1-ethynyl-2-(phenylbuta-1,3-diynyl)benzene, and enetetrayne, 1,2-bis(phenylbuta-1,3-diynyl)benzene, respectively. Solid state structural and thermal analyses are also described. In solution, 1-ethynyl-2-(phenylbuta-1,3-diynyl)benzene was found to undergo thermal Bergman cyclization to afford 2-(phenylethynyl)naphthalene.     

A one-pot, three-component synthesis of thiazolidine-2-thiones

An efficient method for the synthesis of thiazolidine-2-thiones is described via regiospecific iodocyclization of an allyl amine, carbon disulfide, and iodine. Dehydrohalogenation of the iodo-derivatives gives thiazole-2(3H)-thiones. In addition, nucleophilic substitution of the iodine in the products is accomplished using NaN₃, thiophenol, or dithiocarbamate.     

A convenient and mild one pot synthesis of cyclopentenone derivatives

Developed a convenient and mild one pot synthesis of cyclopentenone derivatives using 1-acetyl-1-cyclohexene and wide range of aldehydes. Aromatic and heterocyclic aldehydes with electron donating and withdrawing groups were conveniently converted to the corresponding cyclopentenone derivatives.     

A convenient synthesis of dihydrocoumarins from phenols and cinnamic acid derivatives

A facile procedure for synthesis of dihydrocoumarin derivatives was described. Although the yield of the products in the reaction of phenols with acrylates in trifluoroacetic acid in the presence of Pd(OAc)₂ giving coumarins was found to be very low, dihydrocoumarin derivatives were obtained in good to high yields in the absence of Pd(OAc)₂ when ethyl cinnamates bearing electron-donating groups were employed in this reaction.     

A convenient laboratory synthesis of 2-oxazoline

The reaction of 2-chloroethylformamide ( 1a ) with sodium hydride, in N-methyl-2-pyrrolidone, at reduced pressure, gave anhydrous 2-oxazoline ( 2a ) in good yield.     

A convenient synthesis of 2-chromonecarboxylic acids

Knoevenagel condensation of the β-ketosulfinyl intermediate II with butyl glyoxylate afforded the butyl 2-hydroxy-4-(2-hydroxyphenyl)-3-methylsulfinyl-4-oxobutyrates (III). Compounds III are versatile intermediates for the synthesis of either 2-chromonecarboxylates (V) or 2-carboxy-methylene-3-coumaranone esters (VII).     

CeCl3·7H2O-NaI catalyzed intramolecular addition reactions of 7-hydroxy-1,3-dienes: a facile approach to hexahydrobenzofurans and tetrahydrofurans

CeCl₃·7H₂O-NaI effectively catalyzed intramolecular cyclization of cyclic 7-hydroxy-1,3-dienes, yielding hexahydrobenzofurans in diastereoselective fashion. This cyclization has been applied to synthesize tetrahydrofurans from acyclic 7-hydroxy-1,3-dienes.     

A convenient synthesis of 2-tetrahydrofuranyl ethers

[reaction: see text] A wide spectrum of alcohols and phenols are readily transformed to the corresponding 2-tetrahydrofuranyl ethers in good to excellent yields using CrCl2 and CCl4 in THF under nearly neutral conditions at room temperature.     

New approach to the synthesis of tetrazole-containing buta-1,3-diynes: The total synthesis of 1,4-bis(2-(tert-butyl)-2H-tetrazol-5-yl)buta-1,3-diyne

An approach for the total synthesis of 1,4-bis(2-(tert-butyl)-2H-tetrazol-5-yl)buta-1,3-diyne was reported. Developed approach to the synthesis of 1,4-bis(2-(tert-butyl)-2H-tetrazol-5-yl)buta-1,3-diyne can be used for obtaining different 2,5-bis(tetrazol-5-yl)-disubstituted five-membered heterocycles (e.g. thiophenes, pyrroles, furans etc.), as well as tetrazole-containing monomers for the synthesis of new types of electroconductive and high energetic polymers.     

A convenient one-pot synthesis of boroxoles from diboronic acid

The preparation of the boroxole motif traditionally relies on a 3-step process and the use of n-butyl lithium that can limit substrate scope. Herein during our exploration toward novel RORγ inhibitors, we identified a convenient one-pot preparation of the motif in good yields with good substrate scope.