Synthesis and Transformations of 5-Substituted 2-Furoyl Phosphonates

5-Chloromethyl-2-furoyl chloride when treated with triethyl phosphite has given 5-chloromethyl-2-furoyl phosphonate. This compound has reacted with sodium azide in the presence of potassium iodide to give 5-azidomethyl-2-furoyl phosphonate. Treatment of 5-chloromethyl-2-furoyl phosphonate with secondary amines even under mild conditions has caused cleavage of P–C bond with liberation of diethyl hydrogen phosphite and formation of 5-chloromethyl-2-furancarboxamide. Butanthiol in the presence of potassium carbonate in acetonitrile has converted the chloromethyl group into the butylthiomethyl one and simultaneously split the P–C bond with the formation of the corresponding thioester. Under the action of S-methylthiuronium iodide and triethylamine, 5-chloromethyl-2-furoyl phosphonate has been unexpectedly reduced into the 5-methyl derivative. 5-Butylthiomethyl- and 4-(N-morpholinomethyl)-2-furoul chlorides have been phosphorylated with triethyl phosphite into the corresponding 5-functionalized 2-furoyl phosphonates. The prepared furoyl phosphonates have reacted with resonance-stabilized phosphoranes to give phosphorylated derivatives of 3-(furyl)acrylates and 4-(furyl)but-3-en-2-one with trans-location of phosphoryl and carbonyl groups with respect to the double bond.

     

Synthesis of 3-(furyl)acrylates containing several phosphonate groups

Isomeric (diethoxyphosphorylmethyl)furoyl phosphonates react with ethoxycarbonylmethylenetriphenylphosphorane to form 3-[(diethoxyphosphorylmethyl)fyryl]-3-(diethoxyphosphoryl)acrylates with trans-location of phosphonate and ester groups regardless of the structure of heterocyclic residue. 2,5-Bis(diethoxyphosphorylmethyl)-3-furoyl phosphonate and 4,5-bis(diethoxyphosphorylmethyl)-2-furoyl phosphonate prepared from the corresponding acid chlorides via the Arbuzov reaction behave analogously. The dependence of coupling costants J _PP and J _PC on the location of phosphorus-containing substituents in the furan ring of these compounds is analyzed.     

Synthesis of Isomeric (Methoxycarbonyl)furoyl Phosphonates and Their Reaction with Ethoxycarbonylmethylenetriphenylphosphorane

Addition of diethyl- and diisopropyl hydrogen phosphites to isomeric (methoxycarbonyl)-2- and 3-furaldehydes in the presence of sodium ethylate or potassium fluoride led to the formation of the corresponding hydroxyphosphonates. When treated with DMSO-acetic anhydride mixture at room temperature these compounds were selectively oxidized to the corresponding furoyl phosphonates. 2-Methoxycarbonyl-3- furoyl phosphonate was synthesized via the Arbuzov reaction from 2-methoxycarbonyl-3-furoyl chloride and triethyl phosphite. The obtained isomeric (methoxycarbonyl)furoylphosphonates regardless of the structure of heterocyclic fragment react with ethoxycarbonylmethylenetriphenylphosphorane to give ethyl 3-(furyl)-3-(dialkoxyphosphoryl) acrylates with trans-location of phosphoryl and carbonyl groups against the double bond.     

Synthesis and molecular structure of 1-(pyrimidin-2-yl)-2-(4-aryl-1,3-thiazol-2-yl)hydrazines

Reactions of some 2-hydrazinopyrimidine hydrochlorides with potassium thiocyanate gave 1-(pyrimidin-2-yl)thiosemicarbazides which underwent Hantzsch condensation with aryl chloromethyl ketones to produce 1-(pyrimidin-2-yl)-2-(4-aryl-1,3-thiazol-2-yl)hydrazine hydrochlorides. The protonation was accompanied by mutually dependent tautomeric rearrangements of heterocyclic fragments.     

Synthesis of trifluoromethyl derivatives of alkyl 2-nitromethylphosphonopropionates and -phosphonobutyrates

By adding diethyl hydrogen phosphite to 5-trifluoromethyl-2-furaldehyde (5-trifluoromethylfur-2-yl)(diethoxyphosphoryl)methanol was synthesized. It was oxidized with DMSO-acetic anhydride mixture to diethyl 5-trifluoromethyl-2-furoyl phosphonate. The reaction of the latter with ethoxymethylenetriphenylphosphorane gives ethyl (2E)-3-(diethoxyphosphoryl)-3-(5-trifluoromethylfur-2-yl)propenoate. Analogous reaction of (diethoxyphosphoryl)(5-trifluoromethylfur-2-yl)acetic aldehyde yields ethyl (4E)-4-(diethoxyphosphoryl)-4-(5-trifluoromethylfur-2-yl)-but-3-enoate. The addition of nitromethane to these esters of unsaturated acids in the presence of potassium fluoride gives a mixture of diastereomers of phosphorylated esters of 2-nitromethyl-3-(5-trifluoromethylfur-2-yl)propanoic and 3-nitromethyl-4-(5-trifluoromethylfur-2-yl)butanoic acids respectively. By the reduction of ethyl nitropropanoate with zinc and formic acid in dioxane ethyl 2-aminomethyl-3-(diethoxyphosphoryl)-3-(5-trifluoromethylfur-2-yl)propanoate was prepared in a low yield. It may be considered as the derivative of β-alanine containing additional pharmacophore fragments.     

Synthesis of ethyl 4,5-bis(diethoxyphosphorylmethyl)-3-furoate

Preparative procedure for 4,5-bis(diethoxyphosphorylmethyl)-3-furoate from 4-chloromethyl-3-furoate is developed. It includes substitution of chlorine with iodine, phosphorylation by means of the Arbuzov reaction, chloromethylation of 4-(diethoxyphosphorylmethyl)-3-furoate in the position 5 of the furan ring, substitution of chlorine with iodine in the obtained chloromethyl derivative, and repeated phosphorylation with triethyl phosphite. It was found that ethyl 4-(diethoxyphosphorylmethyl)-5(chloromethyl)-3-furoate reacts with sodium diethyl phosphite by two pathways. Besides usual nucleophilic substitution leading to phosphonate, transfer of the reaction center in the position 2 of the furan ring takes place. The ambident diethylphosphite anion in this case reacts at the oxygen to give tertiary phosphite. The latter is oxidized with the air oxygen to form ethyl 2-(diethoxyphosphoryloxy)-4-(diethoxyphosphorylmethyl)-5-methyl-3-furoate. Unlike that analogous iodomethyl phosphonate is phosphorylated selectively under the conditions of the Arbuzov reaction.     

L-Proline-Catalyzed Knoevenagel Condensation: A Facile,Green Synthesis of (E)-Ethyl 2-Cyano-3-(1H-indol-3-yl)acrylates and (E)-3-(1H-Indol-3-yl)acrylonitriles

L-Proline has been utilized as a novel and ecofriendly catalyst in ethanol medium for the Knoevenagel condensation of indole-3-carboxyaldehydes and their N-methyl derivatives 1(a–e) and 4(a–e) with the active methylene compound, ethyl cyanoacetate (2) to afford substituted (E)-ethyl 2-cyano-3-(1H-indol-3-yl)acrylates 3(a–e) and 5(a–e) respectively. These products were reacted with dimethyl sulfate in the presence of PEG-600 as an efficient and green solvent to afford the corresponding N-mthylated derivatives 5(a–e). These Knoevenagel products react with 5% NaOH, yielding (E)-3-(1H-indol-3-yl)acrylonitriles 6(a–e) and 7(a–e).     

A Novel Route to Acyl Ureas: Syntheses of N-[5-(2-Chlorophenyl)-2-Furoyl]-N'-Arylthioureas and Ureas

A novel route to acyl ureas is described. Reaction of 5-(2-chlorophenyl)-2-furoyl chloride with ammonium thiocyanate first, then arylamine under phase transfer catalysis gives N-[5-(2-chlorophenyl)-2-furoyl]-N'-arylthioureas (1a-o). Compounds 1a-o on oxidation with potassium iodate respectively under reflux result in the formation of N-[5-(2-chlorophenyl)-2-furoyl]-N'-arylureas (2a-o).     

Synthesis of Some Novel 5-(Arylidene)-2-imino-3(pyridin-2-yl)thiazolidin-4-one Derivatives

Treatment of 2-aminopyridine ( 1 ) with chloroacetyl chloride in dry benzene gave 2-chloro-N-(pyridin-2-yl)acetamide ( 3 ), which on further reaction with potassium thiocyanate gave 2-imino-3-(pyridin-2-yl)thiazolidin-4-one ( 4 ) as an intermediate compound for the synthesis of pyridin-2-yl substituted 2-imino-thiazolidine-4-one derivatives. Cyclocondensation reaction of ( 4 ) with a series of aromatic aldehydes gave 5-arylidene derivatives of pyridin-2-yl substituted 2-imino-thiazolidine-4-ones 5a–j . ¹ H and ¹³C NMR spectroscopy, as well as elemental analyses, were used for the identification of these new compounds.     

Thiadiazole ring opening in the derivatives of 2-substituted 5-(1,2,3-thiadiazol-4-yl)-3-furoic acid under the action of bases

Transformations of the derivatives of 2-substituted 5-(1,2,3-thiadiazol-4-yl)-3-furoic acid under the action of bases has been studied. In the presence of potassium tert-butylate in THF, the studied compounds decompose with the cleavage of the thiadiazole ring, liberation of nitrogen, and formation of labile acetylene thiolates. In the presence of methyl iodide, these salts form stable 2-methylthioethynylfurans. Under the action of sodium ethylate in ethanol, thiadiazole ring of ethyl [2-methyl-5-(1,2,3-thiadiazol-4-yl)]-3-furoate is split to form the corresponding sodium acetylene thiolate. Under the action of ethanol, two molecules of this salt give bis(furyl)dithiafulvene. In the DMF–potassium carbonate system, acetylene thiolates react with primary and secondary amines giving thioamides of (4-ethoxycarbonyl-5-methylfur-2-yl)acetic acid. Treating of ethyl 2-methyland 2-N-morpholinomethyl-5-(1,2,3-thiadiazol-4-yl)-3-furoates with hydrazine hydrate leads to hydrazinolysis of the ester group and cleavage of thiadiazole ring resulting in the formation of hydrazides of 4-hydrazinocarbonylfur-2-ylacetic acid. In the case of ethyl 2-acetoxymethyl- and 2-(4-nitrophenoxy)methyl-5-(1,2,3-thiadiazol-4-yl)-3-furoates, thiadiazole ring is retained and exclusively hydrazinolysis of the ester groups is observed.     

Synthesis and selected reactions of 4-(diethoxyphosphorylmethyl)-3-furoic acid

Reduction of 4-(ethoxycarbonyl)-3-furoyl chloride with sodium borohydride in dioxane-DMF mixture leads to an ethyl 4-hydroxymethylfuran-3-carboxylate. The treatment of the latter with thionyl chloride at boiling yields the corresponding chloromethyl derivative. The obtained chloride reacts with one equivalent of sodium iodide in acetone at room temperature to form iodomethylfuran. Halomethylfurans synthesized are phosphorylated with sodium diethyl phosphite and triethyl phosphite to give ethyl 4-(diethoxyphosphorylmethyl)-3-carboxylate. The hydrolysis of this substance with one equivalent of potassium hydroxide in ethanol gives the corresponding furoic acid. Treating this substance in succession with ethyl chloroformate and sodium azide yields furoyl azide which while heating in toluene undergoes rearrangement to phosphorus-containing 3-furylisocyanate. Heating the latter with a mixture of acetic acid and acetic anhydride gives N-[4-(diethoxyphosphorylmethyl) furyl-3]acetamide. 4-(Diethoxyphosphorylmethyl)-3-furoic acid reacts with thionyl chloride to form the corresponding furoyl chloride. Its reduction with sodium borohydride in dioxane-DMF mixture leads to the phosphorylated 3-furylmethanol. Aminomethylation of its acetate with dimethylmethyleneiminium chloride in acetonitrile does not proceed at the ring. Instead of that the unstable ester of 3-(dimethylamino) propionic acid and the phosphorylated 3-furylmethanol are formed. In slightly basic medium free Mannich base decomposed to give the starting acetate.     

Synthesis and Crystal Structure of 4-（4,6-Dimethoxylpyrimidin-2-yl）- 3-thiourea Carboxylic Acid Ethyl Ester

4-（4,6-Dimethoxyl-pyrimidin-2-yl）-3-thiourea carboxylic acid ethyl ester was synthesized by the reaction of 2-amino-4,6-dimethoxyl pyrimidine, potassium thiocyanate and methyl chloroformate in ethyl acetate. Single crystals suitable for X-ray measurement were obtained by recrystallization with the solvent of dimethyl formamide at room temperature. The crystal structure was determined by X-ray diffraction analysis. Crystallographic data： C10H14N4O4S, M, = 286.31, monoclinic, space group C2/c with a = 2.5309（3）, b = 0.67682（6）, c = 1.74237（19） nm, β = 114.744（3）°, V= 2.7106（5） nm3, Dc = 1.403 g/cm3, p = 0.225 mm-1, F（000） = 1200, Z= 8, R= 0.0514 and wR= 0.1529.     

Preparation of new nitrogen-bridged heterocycles. 55. Reinvestigation of the bromination/dehydrobromination of ethyl 3-[2-(methylthio)indolizin-3-yl]acrylate derivatives

The bromination/dehydrobromination reactions of ethyl 3-[1-alkoxycarbonyl-2-(methylthio)indolizin-3-yl]acrylates were reinvestigated. Reactions of the title compounds with two equivalents of bromine, followed by heating of the resulting reaction mixture and then treatment with a base gave the unexpected dialkyl 7-bromothieno[2,3-b]indolizine-2,9-dicarboxylates, while similar reactions using benzyltrimethylammonium tribromide as a brominating agent afforded only non-brominated thieno[2,3-b]indolizine derivatives, which were converted to the corresponding 7-bromo derivatives upon further treatment with bromine.     

Synthesis and Crystal Structure of 4-(4,6-Dimethoxylpyrimidin-2-yl)-3-thiourea Carboxylic Acid Ethyl Ester

4-(4,6-Dimethoxyl-pyrimidin-2-yl)-3-thiourea carboxylic acid ethyl ester was synthesized by the reaction of 2-amino-4,6-dimethoxyl pyrimidine,potassium thiocyanate and methyl chloroformate in ethyl acetate.Single crystals suitable for X-ray measurement were obtained by recrystallization with the solvent of dimethyl formamidc at room temperature.The crystal structure was determined by X-ray diffraction analysis.Crystallographic data:C10H14N4O4S,Mr=286.31,monoclinic,space group C2/c with a=2.5309(3),b=0.67682(6),c=1.74237(19)nm,β=114.744(3)°,V=2.7106(5)nm3,Dc=1.403 g/cm3,μ=0.225mm-1,F(000)=1200,Z=8,R=0.0514 and wR=0.1529.     

3-(Furyl)-3-(diethoxyphosphoryl)acrylates: Synthesis and reaction with nitromethane

A series of 3-(furyl)-3-(diethoxyphosphoryl)acrylates was synthesized by the reaction of 2- and 3-furoyl phosphonates with ethoxycarbonylmethylenetriphenylphosphorane. It was shown that in all cases diethoxyphosphoryl and ester groups were in trans-position with respect to the double bond disregarding the structure of the furan fragment. Potassium fluoride catalyzed addition of nitromethane to the compounds synthesized was studied. It was found that this reaction proceeded regioselectively to form 2-[(furyl)(diethoxyphosphoryl) methyl]-3-nitropropanoic acids.     

Synthesis of azoles from 3-[(3-hydrazino-3-oxopropyl)anilino]-and 3-[(3-hydrazino-3-oxopropyl)-4-methylanilino]propane hydrazides

Condensation of 3-[(3-hydrazino-3-oxopropyl)anilino]-and 3-[(3-hydrazino-3-oxopropyl)-4-methylanilino]propane hydrazides with 2,4-pentanedione, phenyl isocyanate or phenyl isothiocyanate (with subsequent work up of the semicarbazides obtained by base), and carbon disulfide gave respectively: 1-(3,5-dimethyl-1H-1-pyrazolyl)-3-[3-(3,5-dimethyl-1H-1-pyrazolyl)-3-oxopropylanilino]-1-propanone, 3-(2-{[2-(5-oxo-4-phenyl-4,5-dihydro-1H-1,2,4-triazol-3-yl)ethyl]anilino}ethyl)-4-phenyl-4,5-dihydro-1H-1,2,4-triazol-5-one and its thio analog, and 5-(2-{[2-(2-thioxo-2,3-dihydro-1,3,4-oxadiazol-5-yl)ethyl]anilino}ethyl)-2,3-dihydro-1,3,4-oxadiazole-2(3H)-thione plus their methyl derivatives. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1353–1358, September, 2007.     

Functional Derivatives of Ethyl 4-(Chloromethyl)-2,6-dimethylpyridine-3-carboxylate

The condensation of ethyl 4-(chloromethyl)-2,6-dimethylpyridine-3-carboxylate with substituted phenols in ethanol in the presence of potassium carbonate afforded the corresponding aryl pyridin-4-ylmethyl ethers. Analogous condensation with substituted anilines gave 2-aryl-4,6-dimethyl-1,2-dihydropyrrolo[3,4-c]- pyridin-3-ones. Esters containing 1,2-azole fragments were synthesized by acylation of hydroxymethylsubstituted ethers with 5-arylisoxazole- and 4,5-dichloroisothiazole-3-carbonyl chlorides.     

4-functionally substituted 3-hetarylpyrazoles: XX. Synthesis of derivatives of 5-(pyrasol-4-yl)-1,2,4-triazole and 3-(pyrazol-4-yl)-1,2,4-triazolo[3,4-c][1,4]oxazine

N-Methylimines of 3-aryl-1-phenylpyrazole-4-carbaldehyde react with ethyl 2-aryl-hydrazino-2-chloroacetate with the formation of ethyl 1-aryl-5-(pyrazole-4-yl)-4,5-dihydro-1H-1,2,4-triazolecarboxylates. Analogous reactions of pyrazol-4-carbaldehyde N-(2-hydroxy)ethylimines results in derivatives of 3-(pyrazol-4-yl)-1,2,4-triazolo[3,4-c][1,4]-oxazines.     

Synthesis of 4-(1-Adamantyl)- and 4-(1-Adamantylmethyl)-substituted Halothiazoles

1-Adamantyl bromomethyl ketone and 1-adamantylmethyl chloromethyl ketone react with potassium thiocyanate in dimethylformamide to give the corresponding thiocyanatoketones which cyclize under the influence of HCl into 4-(1-adamantyl) and 4(-adamantylmethyl)chlorothiazole respectively. 4-(1-Adamantyl)-2-amino-5-bromothiazole and its N-derivative were synthesized by the reaction of 1-adamantyl dibromomethyl ketone with thioureas and N-substituted thiourea in acetonitrile.