Thiopyran Derivatives Research Articles

Synthesis of [1,3]dithiole and spiro[1,3]dithiole thiopyran derivatives of the [1,2]dithiolo[1,4]thiazine ring system.

We report the synthesis of some new polysulfur-nitrogen heterocycles by cycloaddition reactions to readily available tricyclic condensed 1,2-dithiole-3-thiones. Thus, treatment of bis[1,2]dithiolopyrrole ketothione 1 with diacyl acetylenes gave the bis-aducts 2a-d. On the other hand, cycloaddition of bis[1,2]dithiolo[1,4]thiazine ketothione 3 with 1 equiv of acyl or diacyl acetylenes gave [1,3]dithiolylidenyl[1,2]dithiolo[1,4]thiazines 4a-f in fair to high yields. Catalysis by scandium triflate was used in the reactions that implied the less reactive dipolarophiles. Treatment of 3 with 2 equiv of DBA gave the bis-aduct 5a, and reaction of 4c with DMAD gave the mixed bis-adduct 5b. Cyclic voltammetry of selected examples showed irreversible processes that were influenced by the electrochemical activity of peripheral groups bonded to the heterocyclic system.

Application of Phase Transfer Catalysis in Heterocyclic Synthesis: Synthesis of Some New Polyfunctional Thiophenes, Thiopyrans, Pyridines and Oxazines

The reaction of compound 1 with CS 2 and different active halo compounds gave the corresponding thiophene derivatives 2a,b-4a,b , whereas treatment of compound 1 with CS 2 and active methylene compounds afforded the corresponding thiopyran derivatives 5a,b , 6a,b , 7 , and 8 . Also, 1,3-thioxane derivatives 9 and 10 were obtained by reacting compound 1 with CS 2 and different cycloalkanones. Thiophene and pyrrolidene derivatives 11 , 12a,b , and 13a,b were obtained by reacting compound 1 with phenyl isothiocyanate and different halo compounds. The active methylene compounds and/or cycloalkanones were treated with compound 1 in the presence of phenyl isothiocyanate to give pyridines, thiopyran and oxazine derivatives 14a,b-16a,b , 17a-19a , and 19b , respectively.

Cyanothioacetamide in Heterocyclic Chemistry: Synthesis of Thiopyran, Pyridinethione, Thienopyridine, Pyridothienotriazine and Pyridothienopyrimidine Derivatives

Cyanothioacetamide (1) reacted with α- and β-naphthaldehyde 2a,b to afford the corresponding 3-naphthyl-2-thiocarboxamidopropenonitriles 3a,b. Compounds 3a,b structures could be elucidated via their reactions with acrylonitrile, ethyl acrylate (4a,b). N-arylmaleimides 6a-c and ethyl acetoacetate (8). The isolated products could be represented as the thiopyran, thiopyranopyrrolidine and pyridinethione derivatives 5a-d, 7a-f and 9a,b respectively. Pyridinethiones 9a,b had been used as the starting materials in the present study in addition to the next ones to synthesize several new thienopyridines, pyridothienotriazine and pyridothienopyrimidines 12a-f, 15a,b, 16b, 17–19a,b respectively through their reactions with the corresponding reagents. All structures of the newly synthesized heterocyclic compounds were established on the basis of the data of IR, 1H NMR and elemental analyses.

ChemInform Abstract: Pyrolysis, Photolysis and Mass Spectra of Pyran and Thiopyran Derivatives.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Pyrolysis and Photolysis Processes of Pyran and Thiopyran Derivatives.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Pyrolysis and photolysis processes of pyran and thiopyran derivatives

Pyrolysis and photolysis of 2-amino-3,5-dicyano-6-phenyl-4H-pyran (1) afford HNCO, acrylonitrile, cinnamonitrile, and 2-hydroxy-3,5-dicyano-6-phenylpyridine. Pyrolysis of 2-carboxyimino-3,5-dicyano-6-phenyl-4H-pyran (2) gives HCN, acrylonitrile, cinnamonitrile and 2-hydroxy-3,5-dicyano-6-phenylpyridine. Furthermore, both pyrolysis and photolysis of 2,6-diamino-3,5-dicyanothiopyran (3a) gives rise to HNCS, acrylonitrile and 6-amino-3,5-dicyano-6-mercaptopyridin. Moreover, comparative studies of pyrolysis and photolysis of 2,6-dicyano-4-arylthiopyran derivatives3b–d revealed similar results. The similarity of products obtained from pyrolysis and photolysis and the mechanistic implications of these data are discussed.

ChemInform Abstract: A One‐Pot Synthesis of Thiopyran Derivatives from Ketene S,S‐Acetals and α,β‐Unsaturated Nitriles under PTC Conditions.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Cycloaddition Reactions of (1,2)Dithiolo(1,2)dithiole Derivatives with Dimethyl Acetylenedicarboxylate: Formation of New Bi‐, Tri‐ and Tetracyclic Thiopyran Derivatives.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Cycloaddition Reactions of [1,2]Dithiolo[1,2]dithiole Derivatives with Dimethyl Acetylenedicarboxylate: Formation of New Bi-, Tri- and Tetracyclic Thiopyran Derivatives

By cycloaddition reactions of the title compounds 1, new spiro[1,3-dithiole-thiopyran] derivatives 3 and 5 are available. Their cleavage with mercury(II) acetate leads to the corresponding bicyclic thiopyran-4-ones 9 and 10. Starting from 3H,6H-[1,2]dithiolo[4,3-c][1,2]dithiole- 3,6-dithione (1d), besides 4H,8H-2,3,6,7,4′,5′,4″,5″- octa-(methoxycarbonyl)thiopyrano[3,2-b]thiopyran-4-spiro-2′-(1′,3′- dithiole)-8-spiro-2″-(1″,3″-dithiole) (5), the tetra(5′,6′- methoxycarbonyl-1′,4′-dithiino)[2,3-c][2,3-e][2,3-i] [2,3-k]-1,2,7,8-tetrathiacyclododeca-3,5,9,11-tetraene (8) is formed.

Zur Synthese von 6-nitrosubstituierten 2H-Benzo[b]thiopyran-Derivaten aus 2-Mercapto-5-nitro-benzaldehyd

About the Synthesis of 6-nitro-substituted 2H-Benzo[b]thiopyran Derivatives Starting from 2-Mercapto-5-nitro-benzaldehyde Benzene derivatives useful as C3S-building blocks for the synthesis of 2H-benzo[b]thiopyrans are not easily available. The synthesis starting with 2-chloro-benzaldehyde via 2-chloro-5-nitrobenzalde-hyde to 2-mercapto-5-nitro-benzaldehyde-tert-butylimin 1b and its cyclisation to 2H-benzo[b]thiopyrans (2a – h) and (3a – d) is described. By reaction with acceptor substituted alkenes, e.g. acroleine or ω-nitrostyrene respectively 2-chloro-propenes, e.g. substituted ß-chloroacroleines or 2-chloro-propene-1,3-dicarboxylates the compounds 2a – h and 3a – d are obtained. Vilsmeier's reaction of the diester 3d with DMF/POCl3 yields the formyl compound 4.

ChemInform Abstract: Reactions of Allene‐1,3‐dicarboxylic Esters. Part 8. Syntheses of 2‐Methoxycarbonylmethylene‐2H‐thiopyran‐3‐carboxylic Esters.

AbstractReaction of the enamino ketones (I) with the allene dicarboxylate (II) gives rise to the thiopyran derivatives (III).

ChemInform Abstract: Reactions of Some Dienophiles with 3‐Aryl‐2‐cyanothioacrylamides: Synthesis of New Thiopyran Derivatives.

ChemInform Abstract: Reactions of Some Dienophiles with 3‐Aryl‐2‐cyanothioacrylamides: Synthesis of New Thiopyran Derivatives.

ChemInform Abstract: Sulfur‐Bridged Cyclodecenones from Thioaldehyde Diels‐Alder Adducts.

AbstractThe thioaldehyde (II) generated from (I) reacts in situ with the siloxybutadien (III) to form the thiopyran derivative (IV).

ChemInform Abstract: Synthesis of 3‐Cyano‐δ2‐ and ‐δ3‐dihydropyran and ‐thiopyran Derivatives.

AbstractTreatment of the compounds (I), (III), and (VI) with p‐toluenesulfonic acid in acetic anhydride yields the elimination products (II), (IV), and (V), or (VII).

Synthesis of 3-cyano-Δ 2- and -Δ 3-dihydro-pyran and -thiopyran derivatives

Treatment of trans,trans-3,5-diacyloxy- r-4- tert-butoxycarbonyl-4-cyano-tetrahydropyran ( 1a–b) and -tetrahydrothiopyran ( 1c–d), 5-(2,4-di- O-acyl-3- tert-butoxycarbonyl-3-cyano-3-deoxy-β- d- xylo-pentopyranosyl)-3-ethoxycarbonyl-2-methylfuran ( 2a–b) and -3-acetyl-2-methylfuran ( 2c–d), and methyl 2,4,6-tri- O-acetyl-3- tert-butoxycarbonyl-3-cyano-3-deoxy-α- d- gluco-hexopyranoside ( 3) with toluene- p-sulfonic acid in acetic anhydride gave the corresponding branched unsaturated compounds, 5-acyl-4-cyano-5,6-dihydro-2 H-pyran ( 4a–b) and -thiopyran ( 4c–d), 5-(4- O-acyl-3-cyano-2,3-dideoxy-β- d- glycero-pent-2-enopyranosyl)-furans ( 5a–d) (minor), 5-(2- O-acyl-3-cyano-3,4-dideoxy-β- d- glycero-pent-3-enopyranosyl)furans ( 6a–d) (major), and methyl 2,6-di- O-acetyl-3-cyano-3,4-dideoxy-α- d- erythro-hex-3-enopyranoside ( 7).

Thermal cycloaddition reaction of xanthene‐9‐thione with allenes: An ESR study

AbstractDuring the parallel (2 + 2)‐ and (4 + 2)‐cycloaddition reactions of aromatic thiones such as xanthene‐9‐thione with substituted allenes XCHCCH2 (X = OR, SR, NMe2, Ph), a strong ESR signal is observed. This signal is associated with the (4 + 2)‐cycloaddition reaction, affording thiopyran derivatives 3,11b‐dihydro‐2‐(X‐methylene)‐2H‐thiopyrano[4,3,2‐kl]xanthene F or 3,11b‐dihydro‐3X‐2‐methylene‐2H‐thiopyrano[4,3,2‐kl]xanthene E. Computer analyses of this signal made possible its identification as emanating from a 9‐xanthenyl radical substituted at the 1‐ and 9‐positions. The type of xanthenyl radical that is formed in the thermal reaction E rad or F rad depends on the nature of the substituent X at the allenic system H2CCCHX. This investigation shows that where X = Ph and NMe2, xanthenyl radicals of structure E rad are produced, and where X = O‐t‐Bu and S‐t‐Bu xanthenyl radicals of structure F rad are produced. It is striking that this production is so selective.On irradiation (λ>254nm), the production of xanthenyl radicals is enhanced. The conformation of xanthenyl radicals E rad and the role of E rad and F rad in the formation of addition products E and F are discussed.

Cycloaddition Reactions of Substituted Allenes with Triplet Excited Aromatic Thiones: Product Formation and Reaction Mechanism

AbstractThe reactivity of substituted allenes H2CCC(R)X towards three triplet aromatic thiones has been investigated. Product analysis reveal the formation of two (2+2)‐cycloaddition products the thietanes 3, 4 (E + Z) and occasionally of one (4+2)‐cycloaddition product, thiopyran derivative (Z)‐5, generally in high overall yields. Steady state measurements show that electron donating substituents in the allenic system enhance the overall reaction rate. There is little effect of solvent polarity on the reaction rate. The correlation between the relative reaction rates and the first adiabatic ionization energy of the substituted allenes is in accordance with the formation of an exciplex between the excited thione and that π‐bond of the allenic system which is conjugated with the substituent X. From this exciplex two isomeric allylic 1,4‐biradicals (Z)‐8 and (E)‐8 are probably formed. After inter‐system crossing, ring closure gives the thietanes 3, (E)‐4, (Z)‐4 and/or thiopyran derivative (Z)‐5. The ratio in which 3, (E)‐4, (Z)‐4 and (Z)‐5 are formed is explained by considering electronic and steric factors in the proposed reaction mechanism. Experiments with an optically active allene (+)‐PhC(H)CC(H)Me support the intermediacy of a non‐chiral relatively stable allylic 1,4‐biradical. At infinite allene concentration the quantum yield approaches 1, indicating no energy loss during the reaction. Thus no measurable disproportionation of the allylic biradicals (Z)‐8 and (E)‐8 occurs.

Simple method for the synthesis of thiopyran derivatives

Simple method for the synthesis of thiopyran derivatives

Kinetic and thermodynamic study of the reaction of 2,4,6-triphenylthiopyrylium ion with butylamine and cyclohexylamine in dimethyl sulfoxide

A kinetic and thermodynamic study of the reaction of the 2,4,6-triphenylthiopyrylium ion (1) with butylamine and cyclohexylamine has been performed in Me2SO at 25°C. The reaction involves the initial formation of both the corresponding 2H- and 4H-thiopyrans, which equilibrate to form only the more stable 2H adduct. The kinetic data are consistent with a two-step process wherein the formation of the protonated 2H- and 4H-thiopyran intermediates is the rate-controlling step. A comparison with the addition reaction of 1 with CH3O- shows that the relative stabilities of the 2H and 4H isomers are strongly affected by the charge of the thiopyran derivative. Equilibrium data indicate that the acidity of the ammonium ion is strongly enhanced by the presence of the thiopyranyl moiety. © 1984 American Chemical Society.

ESR identification and conformation of a persistent free radical in the (4+2)-cycloaddition reaction of xanthenethione with phenylallene

In the (4+2)-cycloaddition reaction of xanthenethione 1 with phenylallene 2 to give amongst other, thiopyran derivative 6 and thiopyran 7 as the isolable product, a ketyl radical has been found and identified by ESR spectroscopy. Its conformation and role in the formation of compound 6 are discussed.