Dithietanes. Synthesis of N-substituted 2-imino-1,3-dithietanes and 2-imino-1,3-dithietane hydrochloride

The reaction of diethylphosphoryl isothiocyanate with potassium hydrosulfide gave potassium diethoxyphosphinyldithiocarbamate ( 3a ). This salt, with methylene bromide, afforded 2-diethoxyphosphinylimino-1,3-dithietane ( 5a ) in high yield. In concentrated hydrochloric acid, 5a was hydrolyzed to 2-imino-1,3-dithietane which was isolated as a stable hydrochloride ( 7 ). The synthesis of some other N-Substituted 2-imino-1,3-dithietanes is also described.     

A novel entry toward 2-imino-1,3-thiazolidines and 2-imino-1,3-thiazolines by ring transformation of 2-(thiocyanomethyl)aziridines

A new, efficient, and straightforward synthesis of 3-arylmethyl-4-chloromethyl-2-imino-1,3-thiazolidines and 2-(N-acylimino)-3-arylmethyl-4-chloromethyl-1,3-thiazolidines has been developed by ring transformation of 1-arylmethyl-2-(thiocyanomethyl)aziridines upon treatment with a catalytic amount of titanium(IV) chloride in dichloromethane. The latter 2-(thiocyanomethyl)aziridines were prepared in high yields from 1-arylmethyl-2-(bromomethyl)aziridines by reaction with potassium thiocyanate in DMF. The 2-imino-1,3-thiazolidines and 2-(N-acylimino)-1,3-thiazolidines thus obtained can be easily interconverted, either by treatment with an acid chloride and a base in ether toward 2-(N-acylimino)thiazolidines or by treatment with potassium carbonate in methanol toward N-deprotected 2-iminothiazolidines. Dehydrohalogenation of 2-(N-acylimino)-3-arylmethyl-4-chloromethyl-1,3-thiazolidines by means of potassium tert-butoxide in DMSO afforded 2-(N-acylimino)-4-methyl-2,3-dihydro-1,3-thiazolines in good yields.     

Regiospecific iodocyclization of S-allyl dithiocarbamates: synthesis of 2-imino-1,3-dithiolane and 2-iminium-1,3-dithiolane derivatives

4-Alkyl-2-imino-1,3-dithiolanes and 4-alkyl-2-iminium-1,3-dithiolanes were prepared in excellent yields with complete regiospecificity under mild conditions by the iodocyclization of S-allyl dithiocarbamates. Dehydrohalogenation of the 4-alkyl-2-imino-1,3-dithiolanes gave 4-alkylidene-2-imino-1,3-dithiolanes in excellent yields.     

Ring-chain transformations of substituted 2-imino-1,3-thiazinoazoles

The ring-chain transformations of substituted 2-imino-1,3-thiazinoazoles in DMSO under the influence of tetraalkylammonium or alkali metal hydroxides were studied by acid-base potentiometric titration and PMR, IR, and UV spectroscopy.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 992–994, July, 1988.     

Synthesis of 2-substituted benzo-1,3-ditelluroles

A method for the synthesis of 2-phenylbenzo-1,3-ditellurole by the reaction of disodiumo-benzeneditellurolate with benzylidene chloride was proposed. 2-Methylbenzo-1,3-ditellurole and benzo-1,3-ditellurole-2-carboxylic acid were prepared by the reaction of 2-lithiobenzo-1,3-ditellurole with MeI and CO₂, respectively. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1132–1134, June, 2000.     

Preparation and radical ring-opening polymerization of 2-substituted-4-methylene-1,3-dioxolanes

2-Methyl-2-phenyl-4-methylene-1,3-dioxolane ( IIa ), 2-ethyl-2-phenyl-4-methylene-1,3-dioxolane ( IIb ), 2-phenyl-2-(n-propyl)-4-methylene-1,3-dioxolane ( IIc ), 2-phenyl-2-(i-propyl)-4-methylene-1,3-dioxolane ( IId ), 2-(n-heptyl)-2-phenyl-4-methylene-1,3-dioxolane ( IIe ), 2-methyl-2-(2-naphthyl)-4-methylene-1,3-dioxolane ( IIf ), and 2,2-diphenyl-4-methylene-1,3-dioxolane ( IIg ) were prepared and polymerized in the presence of a radical initiator. IIa–IIf were found to undergo vinyl polymerization with ring-opening reaction accompanying the elimination of ketone groups in bulk. IIg was found to undergo the quantitative ring-opening reaction accompanying the elimination of benzophenone in solution to obtain polyketone without any side reaction.     

Investigation on radical polymerization of 2-methylene-1,3-dioxolanes and 2-methylene-1,3-oxazolidines

The reaction of 2-methylene-1,3-dioxolanes and 2-methylene-1,3-oxazolidines with benzoyl peroxide (acceptor radical) and with N-ethylmaleimide (acceptor) was investigated. It was shown that benzoyl peroxide adds to monomers 1a and 1b , giving the corresponding linear diester amides 1a and 1b respectively. The oxazolidine 1c adds benzoyl peroxide, without ring opening, by addition to the exomethylene group. Together with N-ethylmaleimide the oxazolidines 1a or 1b produce deep-colored charge transfer complexes, resulting in high molecular poly-N-ethylmaleimides probably via a radical mechanism. The 1,3-dioxolanes 2a and 2b were radically polymerized to produce polyacetals by vinyl polymerization. 2c was polymerized to produce randomly containing acetal units and ester units. The mechanism of polymerization of 2e is complex, affording polymers of nonuniform character. 2-Methylene-4-phenyl-1,3-dioxolane polymerization leads to polyester as the main structure, and to a lesser degree polyacetal structures. The chemical structures of the polymers were confirmed by NMR spectra and elemental analysis. © 1996 John Wiley & Sons, Inc.     

Solid-phase synthesis of tetrasubstituted 2-imino-1,3-thiazolines using a functionalizing cleavage strategy

A novel solid-phase synthesis of tetrasubstituted 2-imino-1,3-thiazolines using a functionalizing cleavage strategy is described. The synthetic route utilized the ambident reactivity of a dithiocarbamate functionality to synthesize the key resin-bound electrophilic thiazolium intermediate. The desired products were efficiently obtained in high purity by the reaction of various amines with the thiazolium salt.     

1,3-Dipolar cycloaddition of phthalazinium ylides to 5-arylidene-2-spirocyclohexane-1,3-dioxane-4,6-diones

Tetrahydrospiropyrrolo[2,1-a]phthalazines were synthesized by the reaction of 5-arylidene-2-spirocyclohexane-1,3-dioxane-4,6-diones with phthalazinium ylides. One of the reaction products, viz., 3-ethoxycarbonyl-2-(4-methoxyphenyl)-2′,2′-pentamethylene-1,2,3,10b-tetrahydrospiro[pyrrolo[2,1-a]phthalazine-1,5′-[1,3]dioxane]-4′,6′-dione, was studied by X-ray diffraction. The spectroscopic characteristics of the reaction products are discussed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2362–2365, October, 2005.     

Selective synthesis of novel 2-imino-1,3-selenazolidin-4-ones and 2-amino-1,3,4-selenadiazin-5-ones from isoselenocyanates

An efficient and regioselective synthesis of 2-imino-1,3-selenazolidin-4-ones and 2-amino-1,3,4-selenadiazin-5-ones was achieved via one-pot reaction of isoselenocyanates, hydrazines, and ethyl chloroacetate or chloroacetyl chloride, respectively. Plausible mechanisms for these transformations were given.     

Synthesis of 1,3-Dialkylimidazolium and 1,3-Dialkylbenzimidazolium Salts

A number of N-alkylimidazoles and N-alkylbenzimidazoles were synthesized by reactions of imidazole and benzimidazole with alkyl halides. The reaction rate increases by a factor of 2 to 3 under conditions of microwave activation. Subsequent treatment of the resulting N-alkylazoles with alkyl halides afforded the corresponding 1,3-dialkylimidazolium and 1,3-dialkylbenzimidazolium halides.     

Reactions of fluoroalkyl-containing lithium 1,3-diketonates with diaminoarenes and 2-aminobenzenethiol

1,5-Benzo[b]- and 1,5-naphtho[2,3-b]diazepines were synthesized by the reaction of lithium 1,3-diketonates with 1,2-diaminobenzene and 2,3-diaminonaphthalene in an MeOH-AcOH-HCl mixture at 0 °C. The reactions of fluoroalkyl-containing lithium 1,3-diketonates with 1,2-diaminobenzene and 1,2-diamino-4,5-difluorobenzene under reflux in acetic acid afford 2-fluoroalkyl-containing benzimidazoles as the major products, whereas the reaction with 2-aminothiophenol gives 2-phenylbenzothiazole. The reactions of lithium diketonate containing the cyclohexane and cyclopentane moieties with 1,2-diaminoarenes and 2-aminobenzenethiol are accompanied by the opening of the carbocycle to form 2-(6-oxo-7,7,7-trifluoroheptyl)benzimidazole and 2-(5-oxo-6,6,6-trifluorohexyl)benzothiazole hydrates, respectively.     

Rearrangements of the aminoalkylation products of tetrahydro-2H-1,3-oxazine-2-thione

The nature of the compounds afforded by the rearrangement of the aminopropylation and aminoethylation products of tetrahydro-2H-1,3-oxazine-2-thione (I) has been investigated. In both instances compounds that can be considered to result from ring opening at either the C-O or C-S bond of a hypothetical bicyclic intermediate of structure IV were obtained. The compounds required for identification of the rearrangement products have been prepared by the reaction of the 2-methylthio derivatives of 2-thiazoline, 5,6-dihydro-4H-1,3-thiazine, and 5,6-dihydro-4H-1,3-oxazine with the appropriate hydroxyalkylamine or mercaptoalkylamine.     

Reactions of 1,3-dihalopropan-2-ones with sodium quinoline-8-thiolate

Mechanochemical reaction of sodium quinoline-8-thiolate with 1,3-dichloropropan-2-one gave 1-chloro-3-(quinolin-8-ylsulfanyl)propan-2-one. 1,3-Bis(quinolin-8-ylsulfanyl)propan-2-one was formed in the reaction of the same reagents in methanol solution. Mechanically activated reaction of sodium quinoline-8-thiolate with 1,3-diiodopropan-2-one resulted in the formation of 9,20-dioxo-8,9,10,19,20,21-hexahydro-[1,11,4,8]dithiadiazacyclotetradecino[2,3,4-ij: 10,9,8-i′j′]diquinoline-18,22-diium diiodide.     

Reactions of 2-diaminomethylidenecyclohexane-1,3-diones with diethyl malonate

The debenzoylation of 2-[(amino)(benzoylamino)methylidene]cyclohexane-1,3-diones (addition products of cyclohexane-1,3-diones with benzoylcyanamide) affords the corresponding 2-diaminomethylidenecyclohexane-1,3-diones. The latter act as N,N-dinucleophiles in reactions with diethyl malonate in the presence of MeONa to form 6-hydroxy-2-(2,6-dioxocyclohexylidene)-1,2-dihydropyrimidin-4(3H)-ones. This reaction performed at 200 °C in the absence of bases results in the subsequent self-condensation of the dihydropyrimidinones to give 4,5′-bipyrimidine derivatives.     

Synthetic studies toward 4H-1,3-benzodioxin-2-ones

The investigation into the synthesis of 4H-1,3-benzodioxin-2-ones, utilizing the corresponding 2-(hydroxy-methyl)phenol as the starting diol, is described. The results illustrate that the synthesis of 4H-1,3-benzodi-oxin-2-ones can be achieved utilizing carefully controlled reaction conditions, in a 3–15% yield.     

Ring-expansion polycondensation of 2-stanna-1,3-dioxepane (or 1,3-dioxepene) with dicarboxylic acid chlorides

2,2-Dibutyl-2-stanna-1,3-dioxepane 1 (or 1,3-dioxepene 2) were prepared from 1,4-butane (or 1,4-butene) diol and dibutyltin dimethoxide. They were polycondensed at 80°C in n-heptane with adipoyl-, suberoyl, sabacoyl chloride and with decane-1,10-dicarbonyl chloride. In the case of suberoyl chloride and 2,2-dibutyl-2-stanna-1,3-dioxepane reaction time, temperature and stoichiometry were varied to optimize both the molecular weight and the fraction of cyclic polyesters. With a slight excess of the dicarboxylic acid chlorides, only macrocyclic polyesters were obtained in all cases. The resulting cyclic polyesters were characterized by viscosity measurements, by ¹H and ¹³C NMR and by MALDI-TOF mass spectrometry.     

Rearrangement of Derivatives of 1,3-Dithian-5-amineinto Bicyclic 2-Thiazolidines. Crystal Structures of cis- and trans-1-(2-Aryl-1,3-dithain-5-yl)-2-thioureas and cis- and trans-5-Aryl-3-imino-7,7a-dihydro-1H,3H,5H-thiazolo[3,4-c]thiazoles

Under conditions normally applied to transform thioureas into the corresponding carbodiimides, cis- and trans-1-(2-aryl-1,3-dithian-5-yl)-2-thioureas 7 and 8 undergo a rearrangement to 5-aryl-3-imino-7,7a-dihydro-1H, 3H, 5H-thiazolo[3,4-c]thiazoles 9/10 with cis- and trans-fused rings, respectively. The structures of these novel heterocycles were established by X-ray analysis of compounds 9a , 9d , and 10d . The cis-fused compounds 9 are the thermodynamically more stable ones. The stereochemical outcome of the rearrangement depends on the carbenium ion stabilizing capability of the aryl moiety and on the reagent system applied. With Ar = Ph, p-Cl-Ph, p-O₂N-Ph, the reaction can be directed to deliver mainly either the cis-thiazolothiazoles 9 or the trans-thiazolothiazoles 10 . With Ar = 5-methyl-4-imidazolyl or p-Me₂N-Ph, formation of the cis-thiazolothiazoles ( 9a and 9b , resp.) is strongly favored independently of the reaction conditions, In contrast to it 2-aryl analogs, (1,3-dithian-5-yl)-2-thiourea 7g can be transformed into the carbodiimide 11 . Under rigorous conditions, 11 also undergoes rearrangement to the corresponding thiazolothiazole 9g . Mechanisms explaining the above findings are discussed. Reaction of trans-2-phenyl-1,3-dithian-5-amine 6d with phosgene or trichloromethyl chloroformate gives the 5-phenyl-7,7a-dihydro-1H,3H,5H-thiazolo[3,4-c]-thiazol-3-ones 12 and 13 , whereas the amine 5g lacking an aryl substitutent forms the sable isocyanate 14 . Compound 14 is transformed into the corresponding thiazolothiazolone 15 by refluxing in diglyme. Syntheses are described for the 1,3-dithian-5-amines 5 / 6 and the thioureas 7 / 8 derived therefrom. The relative configuration of 7d and 8d was determined by X-ray analysis. NMR data then allowed to assign the configurations of all compounds of types 7 and 8 .     

Synthesis and Structure of Quaternary Salts Derived from 2-Anilino- and 2-Benzylamino-5,6-dihydro-4H-1,3-thiazine

Substituted phenacyl bromides react with 2-anilino-5,6-dihydro-4H-1,3-thiazine at the exocyclic nitrogen atom and with 2-benzylamino-5,6-dihydro-4H-1,3-thiazine at the nitrogen atom in the ring. The structure of the reaction intermediates was elucidated, and their cyclization into 1-benzyl-2-aryl-6,7-dihydro-5H-imidazo[2,1-b][1,3]thiazinium bromides was performed.     

Synthesis of novel 1,3-dithiolan-2-one derivatives

Novel 1,3-dithiolan-2-one derivatives were prepared starting from α, β- or β, γ-dichlorinated carboxylic esters and potassium O-ethyl dithiocarbonate. The scope and the mechanism of this reaction were investigated. The biological uses of the compounds obtained here were examined.