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A highly enantioselective cascade sulfa-Michael/Julia-Kocienski olefination reaction between 2-mercaptobenzaldehydes and β-substituted vinyl PT-sulfones has been realized for the synthesis of 3,4-unsubstituted 2H-thiochromenes. This reaction, catalyzed by diphenylprolinol TMS ether, proceeds through an aromatic iminium intermediate and furnishes a wide range of 2-substiuted 2H-thiochromenes with excellent enantioselectivities (up to 99:1 er).

The Cu-catalyzed domino synthesis of multi-substituted benzo[b]thiophene through radical cyclization of 2-iodophenyl ketones was developed using xanthate as a sulfur surrogate. This method was extended to obtain tetracyclic Lupinalbin analogues through do

An alternative green method was developed for the synthesis of thio- and selenoflavones by the ring closure of 2-chlorophenyl ethynyl ketone with NaHY (Y = S, Se). These nucleophilic chalcogen species were generated in situ using NaBH4 to reduc

A nickel-catalyzed one-pot carbonylation reaction of 2-bromobenzenesulfonyl chlorides with alkynes for the synthesis of thiochromenones has been established. Both terminal and internal alkynes were suitable substrates in this carbonylative transformation, and a broad range of 2-mono- and 2,3-disubstituted thiochromenone products were obtained in moderate to good yields with quite high functional group compatibility. Notably, this procedure presents the first example of nickel-catalyzed carbonylative synthesis of thiochromenones with 2-bromobenzenesulfonyl chlorides as a promising sulfur precursor.

Grignard reagents undergo conjugate addition to thiochromones catalyzed by copper salts to afford 2-substituted-thiochroman-4-ones, both 2-alkylthiochroman-4-ones and thioflavanones (2-arylthiochroman-4-ones), in good yields with trimethylsilyl chloride (TMSCl) as an additive. The best yields of 1,4-adducts can be attained with CuCN-2LiCl as the copper source. Excellent yields of 2-alkyl-substituted thiochroman-4-ones and thioflavanones (2-aryl substituted) are attained with a broad range of Grignard reagents. This approach works well with both alkyl and aromatic Grignard reagents, thus providing a unified synthetic approach to privileged 2-substituted thiochroman-4-ones and a potential valuable precursor for further synthetic applications towards many pharmaceutically active molecules. The use of commercially available and/or readily prepared Grignard reagents will expedite the synthesis of a large library of both 2-alkyl substituted thiochroman-4-ones and thioflavanones for additional synthetic applications.

A new and efficient approach for the synthesis of thioflavones and thioaurones by competitive cascade cyclization of 2′-tosyloxychalcones has been developed. 2′-Tosyloxychalcones were smoothly converted into thioflavones and thioaurones by incorporation of sulfur atom using elemental sulfur and triethylamine in DMSO with good yields. The advantages of the methodology are the formation of both thioflavones and thioaurones in a single step. Easily accessible substrates, mild reaction conditions and compatibility with a broad range of functional groups make this protocol clean and inexpensive.

Copper-catalyzed one-pot synthesis of various 2-arylthiochromenones is developed using xanthate as an odorless sulfur source from easily acquirable 2′-halochalcones. This methodology demonstrates that the cross-coupled product thiochromanone synthesized from 2′-halochalcones (upstream reaction) is oxidized to thiochromenone (downstream reaction) in the same pot using waste byproduct (KI) of the first step as powerful oxidant molecular iodine (I2). This one-pot synthesis has been further extended for the synthesis of 3,3′-methylenebisthioflavone using dimethyl sulfoxide (DMSO) as solvent and methylene source.

A practical synthetic approach to the stereoselective synthesis of Z-vinyl selenides is described through the reaction of sodium selenide with organic halides, followed by the addition to alkynes. The reaction conditions were also successfully applied to

A general, efficient and economic palladium-catalyzed dehydrogenation to form enones or enals has been developed. The approach possesses extremely broad substrate scope including various linear or cyclic saturated ketones and aldehydes. The protocol is ligand-free, and molecular oxygen is used as the sole clean oxidant in the reaction. Due to mild reaction conditions, good functional group compatibility, and versatile utilities of enones and enals, the method can be applied in the late-stage synthesis of natural products, pharmaceuticals and fine chemicals. (Figure presented.).

A flexible and efficient carbonylative synthesis of thiochromenones from the commercially available materials by utilizing tert -butyl isocyanide as carbonyl source has been developed. This methodology efficiently constructs thiochromenones in moderate to excellent yields with the advantages of wide range of substrates and being applicable to library synthesis.

A facile synthetic method to chromenones and thiochromenones has been developed using a one-pot Friedel-Crafts acylation of alkynes with suitably substituted benzoyl chlorides. This unified approach to (thio)chromenones is readily applicable to aryl- and alkylalkynes where the stereochemically well-defined β-chlorovinyl ketone intermediates undergo distinctively different cyclization pathways. The ready availability of both starting materials, alkynes and benzoyl chlorides, coupled with the experimental simplicity makes the current synthetic method to (thio)chromenones fast, efficient, and practical.

4-Quinolone and 4 H -thiochromen-4-one derivatives are readily synthesized in a tandem one-pot manner in good to excellent yields. Starting from (Z)-β-chlorovinyl ketones, an intermolecular nucleo-philic addition of amines or sodium hydrogen sulfide to (Z

An efficient and practical synthesis of benzothiazine by K2S initiated sulfur insertion reaction with enaminones via electron catalysis is developed. This protocol provides a new, environment-friendly and simple strategy to construct benzothiaz

Multicomponent reactions, especially those involving four or even more reagents, have been a long-standing challenge because of the issues associated with balancing reactivity, selectivity, and compatibility. Herein, we demonstrate how the use of a reagen

A practical and versatile synthesis of thioflavones from 2-bromobenzoyl chlorides as potent drug candidates, including derivatives with chloro, methyl, or methoxy substituents on the condensed benzene ring was reported. 4,6-Pyrimidyl di(2-halobenzoates)were readily prepared by acylation of 2 equiv of 1 with 4,6-dihydroxypyrimidine in the presence of 2 equiv of triethylamine in methylene chloride at room temperature. After evaporating methylene chloride, the mixture was dissolved in anhydrous THF and triethylamine hydrochloride was filtered off. The condensed residue was purified by short pathway silica gel column chromatography or recrystallization in 75% EtOAc/n-hexane to give 2 in 85-94% yields. Successful synthesis of 2 equiv of 1-(2-bromophenyl)-3-(hetero)aryl-2-propyn-1-ones was accomplished by reacting 1 equiv of 2 with 2 equiv of (hetero)arylethynylmagnesium bromides. Benzothiopyran ring formation was achieved via the 1,4-addition of hydrosulfide anion and one-pot sequence of bromide substitution. The reaction worked well with electron-withdrawing substituents, such as 7-chloro groups, and electrondonating substituents, such as 7-methyland 6-methoxy groups, in the condensed benzene rings.

A metal-free vinylic carbon-hydrogen bond thiolation has been developed. Under the catalysis of iodine (10 mol%), the cyclization of α-alkenoyl ketene dithioacetals afforded a broad range of polyfunctionalized 2-methylene-3-thiophenones in good selectivity with moderate to excellent yields via tandem iodocyclization and dehydroiodination. The synthetic strategy can also be extended to the cyclization of ortho-methylthiophenyl vinyl ketones leading to 2-methylene-3-benzothiophenones.

A convenient one-pot method for the synthesis of thiochromen-4-ones by the condensation of 2′-haloacetophenone and dithioesters at room temperature in the presence of NaH in DMF in moderate to good yields has been developed. The method involves unusual intramolecular S-arylation. The reaction is operationally facile, readily scalable and offers rapid entry into substituted chromene-4-ones.

A convenient two-step synthesis of 2-arylthiochromen-4-ones (thioflavones) beginning with 1-[2-(1,1-dimethylethylsulfanyl)phenyl]ethanones is described. Thus, 3-aryl-1-[2-(1,1-dimethylethylsulfanyl)phenyl]prop-2-en-1- ones were prepared by the condensation of 1-[2-(1,1- dimethylethylsulfanyl)phenyl] ethanones with aromatic aldehyde in the presence of sodium hydroxide, and were treated with iodine in refluxing N-methylpyrrolidin-2-one (NMP) or propanenitrile to afford the desired products in moderate to fair yields.

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A whole family of annelated 4H-thiopyran-4-ones as the core structural unit was readily synthesized in good yields by a microwave-assisted coupling-addition-SNAr (CASNAR) sequence starting from readily available (het)aroyl chlorides, alkynes and sodium sulfide nonahydrate in a consecutive one-pot three-component reaction. All representatives display a pronounced halochromicity of the absorption bands upon protonation. According to DFT calculations, the electronic ground state of the annelated 4H-thiopyran-4-ones possess a considerable zwitterionic character. The Royal Society of Chemistry 2010.

(Chemical Equation Presented) Racemic thioflavanone (thio)acylhydrazones undergo transformation into racemic 3-acetylspiro[1,3,4-oxa(thia)-diazoline-2, 4′-thioflavans] with trans O(1) or S(1) and Ph(2′eq) under acetylating conditions. Conjugation between the ethylenic bond and sp 2 C(4) in thioflavones encumber both the formation of (thio)acylhydrazones and their subsequent spirocyclization. On the other hand, subsequent dehydrogenation of the thiopyran moiety of spiro compounds results in formation of sp2 C(4) and simultaneous degradation of the spirodiazoline ring.

4H-Thiochromen-4-ones and 4H-thiopyrano[2,3-b]pyridin-4-ones are readily synthesized in good yields by a consecutive one-pot, three-component coupling-addition-SNAr (CASNAR) sequence starting from aroyl chlorides, alkynes, and sodium sulfide no

The synthesis of several hitherto unknown heterocyclic ring systems derived from thioflavone is described. Coupling of various o haloheteroarenecarbonyl chlorides with phenylacetylene gives 1-(o-haloheteroaryl)-3-phenylprop-2-yn-1- ones, which were treate

Two 3-(2-phenyl-4H-thiochromen-4-ylidene)-3H-chromene-2,4-dione derivatives were synthesized and evaluated as reversible redox switches. The prepared purple compound 7 and blue compound 13 instantly changed to colorless when treated with sodium borohydrid

The reaction of silyl ester of S-acyl(aroyl) thiosalicylic acids 3 with (trimethylsilyl)methylenetriphenylphosphorane 4 in step wise fashion leads to the acylphosphoranes 7, which subsequently undergo intramolecular Wittig cyclization on the thiolester carbonyl to afford the 4H-1-benzothiopyran-4-ones 8 in good to excellent yields.

Epimeric thioflavanone sulfoxides (2b) were selectively transformed into thioflavone (1a), thioaurone (3a), and di(2-cinnamoylphenyl) disulfide (4). Disulfide 4 can be recyclized into thioaurones (3a-c) and thioflavanones (2a, 5) with heterolysis of the S - S bond. The 3-p-anisylidene sulfoxide analog of 2b (6) transforms, with fragmentation, into 4′-methoxythioaurone 3b.

Simple, efficient and selective new one-step transformations with DDQ, IBDA and I2/DMSO are presented for the dehydrogenation of thioflavanone (1α), as well as the oxidized (1c) and halogenated (1d) derivatives. Ring- contraction reactions of the 1-oxide 1b and 1d leading to the formation of the benzothiophen derivatives 3a and 5, respectively, are also described.

As a continuation of our structure-activity relationship study of substituted 2-phenyl-4-quinolones and flavonoids as antitumor and antiviral agents, a series of 5,6,7,8-substituted-2-phenylthiochromen-4-ones has been synthesized by condensation of substi

Permanganate oxidation transforms 1-thioflavanone (1a) to the corresponding 1,1-dioxide 1c.Periodate oxidation of 1a affords in the cold mainly the corresponding sulfoxide 1b, and that of 1a or 1-thioflavone 1-oxide (2b) provides on heating 1-thioflavone

Photocleavage reactions of a wide range of ethylene compounds were investigated. Photosensitized oxygenation resulted in formation of their corresponding ketones. On the other hand, photoreaction of these substrates with elemental sulfur yielded the corresponding thioketones. Furthermore, photobehaviour of some ethylene episulfides also was studied. It could be concluded that UV-irradiation provides a rapid and effective desactivation pathway for this class of compounds.

The title compounds, 2-aryl-3-iodo-4H-1-benzopyrans and 2-alkyl or 2-aryl-3-iodo-4H-1-benzothiopyrans, were prepared by reaction of the corresponding heterocyclic derivatives with the iodine-cerium(IV) ammonium nitrate system under mild conditions. The scope and proposed mechanism of the reaction were also demonstrated.

The reaction of S-acyl(aroyl)thiosalicylic acids 2 with N-phenyl(triphenylphosphoranylidene)ethenimine 3 in stepwise fashion leads to the acylphosphoranes 5 which subsequently undergo intramolecular Wittig cyclization on the thiolester carbonyl to afford

The catalytic action of triflic acid and/or aluminium chloride on seven selected aryl thioesters (1-7) gave in all cases aryl thiols, diaryl sulfides, diaryl disulfide, and thianthrene derivatives in addition to the corresponding aryl carboxylic acids.Thioester 5 gave thiochromanone derovatives in good yield under the same conditions.Plausible mechanism were suggested to rationalize the obtained results. Key words: Aryl thioesters; Friedel-Crafts reactions; triflic acid; aluminium chloride.

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A new synthesis of thioflavones from β-keto sulphoxide (12) is described.

We describe a new synthesis of chalcogenochromones and of some of their oxygen, sulfur, selenium and tellurium derivatives.The synthesis involves acidic cyclisation of (o-alkylchalcogenophenyl) ethynyl ketones.

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A series of novel subsituted thiochromones and thiochroman-4-ones was synthesized.Compounds were designed as anlogues of naphthoquinone and as potential "bioreductive alkylating agents" and were tested for antitumor activity.The lead compound, 3-(chloromethyl)thiochromone 1,1-dioxide (4), inhibited Ehrlich ascites tumor growth by 100percent in CF1 male mice at 10 (mg/kg) day ip.Similarly, 18 of the 29 related compounds demonstrated good activity in this tumor screen.Few definitive structure-activity correlations were evident regarding the nature of the 3-substituent.How ever, the 2,3 double bond and a sulfone or sulfoxide were required for activity.Four of the compounds synthesized showed marginal but significant activity against P-388 lymphocytic leukemia.

Addition of aryl selenols and aryl thiols to arylpropiolates under basic conditions followed by saponification gave exclusively β-substituted cinnamates of predominant Z sterochemistry.Neat solutions of aryl selenols or aryl thiols and arylpropiolates aft