Synthesis of 2-(1-Alkoxyvinyl)oxazolidines by Condensation of 2-Alkoxypropenals with 2-Aminoalkanols and Ring-Chain Tautomerism of the Products

Reactions of 2-alkoxypropenals with 2-aminoalkanols afforded tautomeric mixtures of previously unknown 2-(1-alkoxyvinyl)oxazolidines and imino alcohols. The condensation takes 2 h at room temperature (89-100%) or 1-5 min under microwave irradiation. The tautomeric equilibrium shifts toward the open-chain structure with increase in the solvent polarity (CDCl₃, CD₂OD, DMSO-d ₆, D₂O) and temperature. The presence of substituents in the oxazolidine ring raises the stability of the cyclic tautomer.     

Ring-Chain Tautomerism of 1,2,3,4-Tetrahydroquinazolines. The Products of Reaction of 1,3-Dicarbonyl Compounds with 2-Aminomethylaniline

The reaction of 2-aminomethylaniline with 1,3-dicarbonyl compounds gives a series of 1,2,3,4-tetrahydroquinazoline derivatives. A ring-chain tautomeric equilibrium of the type enamine-1,2,3,4-tetrahydroquinazoline is observed in solutions of these compounds and its position depends of the structure of the starting dicarbonyl component and the solvent polarity.     

Synthesis of 2-(1-Arylcarbonyl-1-arylazomethylidene)-thiazolidines by the Reaction of 2-(Arylcarbonyl-methylidene)thiazolidines with Diazobenzenes

A variety of 2-(1-arylcarbonyl-1-arylazomethylidene)-thiazolidenes were synthesized in excellent yields by the reaction of 2-(arylcarbonylmethylidene)thiazolidines with diazobenzenes.     

Regioselectivity of the hydrolysis of 2-(1-alkoxyvinyl)-substituted imidazolidines, 1,3-thiazolidines,and 1,3-oxazolidines

2-(1-Alkoxyvinyl)-1,3-thiazolidines reacted with H₂O or D₂O in the presence of 105 mol % of p-toluenesulfonic acid or trifluoroacetic acid (20°C, 1 h) to give 2-acetyl-1,3-thiazolidine in quantitative yield. 2-(1-Alkoxyvinyl)-3,5-diphenylimidazolidines underwent hydrolysis in the presence of 20 mol % of an acid (20°C, 24 h) at the vinyloxy group with high regioselectivity yielding 2-acetylimidazolidines. Hydrolysis of 2-(1-alkoxyvinyl)-3-phenyl-1,3-oxazolidines in the presence of 10 mol % of p-toluenesulfonic acid (20°C, 5 days) takes two pathways, one of which involves the endocyclic C-O bond with ring opening and the other involves the vinyloxy group to produce 2-acetyl-3-phenyl-1,3-oxazolidine. Unlike phenyl-substituted 1,3-thiazolidines and imidazolidines, hydrolysis of their 3-methyl- and 3,5-dimethyl-substituted analogs in acid medium occurs mainly via ring opening. The observed hydrolysis pathways were interpreted in terms of B3PW91/6-311G(d,p) quantum-chemical calculations.     

Reaction of 2-Alkoxypropenals with 2-Mercaptoethanol

The reaction between 2-alkoxypropenals and 2-mercaptoethanol was studied at 20 and 60°C by means of ^1HNMR and GC-MS methods. Under kinetically controlled conditions (20°C, 7-30 days) with no catalyst the addition of 2-mercaptoethanol to 2-alkoxypropenals occurs along Markownikoff rule. The arising 2'-hydroxyethylthio-2-alkoxypropanal undergoes isomerization into the 2-hydroxy-3-alkoxy-3-methyl-1,4-oxathiane that at heating in the presence of catalytic amounts of acids is converted into 2-methyl-2-formyl-1,3-oxathiolane. The reaction of 2-alkoxypropenals with 2-mercaptoethanol at heating (60°C, 3 h) in the presence of acids affords 2-methyl-2,2'-bi(1,3-oxathiolane) even at 2-mercaptoethanol deficit. At the double excess of the latter the 2-methyl-2,2'-bi(1,3-oxathiolane) was obtained in quantitative yield. The presumable schemes of conversion of 2-hydroxy-3-alkoxy-3-methyl-1,4-oxathiane into 2-methyl-2-formyl-1,3-oxathiolane and 2-acetyl-1,3-oxathiolane are discussed.     

The (E)/(Z)-ratio in the reaction of 5-(2-aryl-2-oxoethyl)-2-thioxo-4-oxo-1,3-thiazolidines with bromine

Summary 3-Aryl-, 3-benzyl-, and 3H-5-(2-aryl-2-oxoethyl)-2-thioxo-4-oxo-1,3-thiazolidines3a–h react with bromine in acetic acid solution to give mixtures of the respective 5-aroylmethylene (E) and (Z) diastereomeric derivatives5 and6. They contain more than 85% of the (E)-diastereomers along with some pure isomers. The intermediacy of the 5-bromo derivatives4 is proven and a plausible route of the reaction is presented. Structures of compounds3–6 are evidenced by analytical and spectral data.

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Das Verhältnis von (E)- und (Z)-Isomeren bei der Reaktion von 5-(2-Aryl-2-oxomethyl)-2-thioxo-4-oxo-1,3-thiazolidinen mit Brom

Zusammenfassung 3-Aryl-, 3-Benzyl- und 3H-5-(2-Aryl-2-oxoethyl)-2-thioxo-4-oxo-1,3-thiazolidine3a–h reagieren mit Brom in essigsaurer Lösung zu Gemischen der entsprechenden diastereomeren 5-Arylmethylen-Derivate ((E) und (Z))5 und6. Sie enthalten mehr als 85% des (E)-Diastereomeren. Die intermediäre Natur der 5-Brom-Derivate4 wird bewiesen; ein Reaktionsweg wird vorgeschlagen. Die Strukturen der Verbindungen3–6 werden durch analytische und spektroskopische Daten abgesichert.

     

Reaction of dichloro- and dibromocarbenes with 2-(vinyloxy)-1,3-butadiene

Conclusions A disubstituted multiple bond has the greatest activity in the reaction of 2-(vinyloxy)-1,3-butadiene with dichloro- and dibromocarbenes. The vinyloxy group stabilizes the transition state less effectively than the alkyl or aryl substituent.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1286–1290, June, 1979.     

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.     

Reaction of Trimethylsilylpropiolyl Chloride with Diamines and 2-Aminoethanethiol

Reaction of 3-trimethylsilyl-2-propiolyl chloride with ethylenediamine and hexamethylenediamine provided previously unknown bis(trimethylsilylpropiolyl)amides. Reactions of the acyl halide with 1,2-phenylenediamine and 2-aminoethanethiol proceeded regioselectively at a single reaction center to furnish amino- and thioamides of trimethylsilylpropiolic acid.     

Substituted 2-methylene-1,3-oxazolidines, -1,3-thiazolidines, -1,3-benzothiazines, -1,3-oxazines, and substituted imidazopyrimidinediones from Cl(CH2)nNCO and Cl(CH2)nNCS and active methylene compounds

The reaction of omega-chloroalkyl isocyanates Cl(CH2)nNCO (n = 2 (2), 3 (4)) and isothiocyanate Cl(CH2)2NCS (3) with active methylene compounds CH2YY' 1 in the presence of Et3N or Na give 2-YY'-methylene-1,3-oxazolidines, (E,Z)-1,3-thiazolidines, and 1,3-oxazines from 2, 3, and 4, respectively. 2-(Chloromethyl)phenyl isocyanate 8 gives with 1 the corresponding benzo-oxazines. Ethyl 2-isothiocyanatobenzoate 10 gives the corresponding benzothiazolinone, whereas the analogous isocyanate 12 gives noncyclic enols. Ethoxycarbonyl isothiocyanate 14 gives an open-chain thioenol or an enol-thioamide. The cyanoamides CH2(CN)CONHR, R = H, Me, CHPh2, give with Et3N and 2 the bicyclic imidazopyrimidinediones 16, derived from two molecules of 2, but with their preformed Na salt they give the 1,3-oxazolidines. Reaction of cyanoacetamide with 3 in the presence of Na gave a tricyclic triaza(thia)indacene, derived from two molecules of 3. A reaction mechanism involving an initial attack of the anion 1- on the N=C=X (X = O, S) moiety gives an anion 18, which cyclizes intramolecularly and after tautomerization gives the mono-ring heterocycle. With the cyanoamides, the N- site of the ambident ion 18 attacks another molecule of 2 giving the anion 20, which by intramolecular attack on the CN, followed by expulsion of the Cl- gives the bicyclic 16 after tautomerization.     

1,3-丙二硫醇替代试剂1-（1,3-二噻-2-亚基）丙酮的缩硫醛/酮化反应

通过易制备的3-(1,3-二噻-2-亚基)-2,4-戊二酮(1b)在酸性条件下的脱乙酰化反应制得1-(1,3-二噻-2-亚基)丙酮(1f),产率为86%. 在MeCOCl/MeOH体系中,常温或回流条件下,化合物1f能作为有效的1,3-丙二硫醇替代试剂与醛和酮进行缩硫醛/酮化反应,高产率(86%～99%)合成1,3-二噻烷衍生物. 与已报道的替代试剂2-(2,4-二氯-1,4-戊二烯-3-亚基)-1,3-二噻烷(1a)、3-(1,3-二噻-2-亚基)-2,4-戊二酮(1b)、2-(1,3-二噻-2-亚基)-3-羰基丁酸甲酯(1c)、2-(1,3-二噻-2-亚基)-3-羰基丁酰胺(1d)和2-(1,3-二噻-2-亚基)-3-羰基丁酸(1e)相比,化合物1f是活性最好的1,3-丙二硫醇替代试剂.     

Tautomerism of 2-(o-hydroxyphenyl)-azines

The tautomeric properties ofo-hydroxyphenylazines have been investigated by¹⁷O NMR and UV spectroscopy. 2-(o-Hydroxyphenyl)-pyridine and itsp-nitrophenole analog II exist in chloroform or ethanol as a phenol A. In the case of 2-(2-hydroxy-5-nitrophenyl)-quinoline the NH-tautomer is realized, the content of which increases when going to the dinitro-analog IV.

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Die Tautomerie von 2-(o-Hydroxyphenyl)-azinen (Kurze Mitteilung)

Zusammenfassung Es wurden die tautomeren Eigenschaften vono-Hydroxyphenylazinen mittels¹⁷O-NMR und UV-Spektroskopie untersucht. 2-(o-Hydroxyphenyl)-pyridin und seinp-Nitrophenol-Analog II existieren in Chloroform und Ethanol als Phenol A. Das 2-(2-Hydroxy-5-nitrophenyl)-chinolin liegt als NH-Tautomer vor, dessen Anteil im Dinitro-Analog IV noch steigt.

     

Synthesis of 2-(1-chloroalkyl)-1,3-benzodithioles and 2-alkylidene-1,3-benzodithioles

Boron trifluoride promoted transdithioacetalization of α-chloroacetals with 1,2-benzodithiol affords good yields of 2-(1-chloroalkyl)-1,3-benzodithioles, which dehydrochlorinates very satisfactorily to the corresponding 2-alkylidene-1,3-benzodithioles.     

Tautomerism and Rotamerism in 2-(2-Phenylhydrazino)pyridine

The title compound is shown by X-ray crystallography and NMR spectroscopy to exist both in the solid state and in solution as such. Deuterium-induced shifts confirm the phenylamino structure for 2-phenylaminopyridine.     

(E)-, (Z)-Interconversion in 3-aroylmethyl-5-arylmethylene-2,4-dioxo-1,3-thiazolidines

Summary The (E)-, (Z)-interconversion in 3-aroylmethyl-5-arylmethylene-2,4-dioxo-1,3-thiazolidines is simply achieved upon treating with phenylhydrazine in acetic acid solutions. Configurational assignments are based on¹H-NMR spectral data.

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(E)-, (Z)-Interkonversion von 3-Aroylmethyl-5-arylmethylen-2,4-dioxo-1,3-thiazolidinen

Zusammenfassung Die (E)-, (Z)-Interkonversion in 3-Aroylmethyl-5-arylmethylen-2,4-dioxo-1,3-thiazolidinen wird durch Behandlung mit Phenylhydrazin in essigsaurer Lösung erreicht. Die Zuordnung von Konfigurationen basiert auf¹H-NMR-Daten.

     

Synthesis of some substituted 1,3-thiazolines and 1,3-thiazolidines

Sodium salts of 2, 2-dimethyl-4-mercapto-5-oxo-1,3-thiazoline and 2-oxo-3-mercapto-1-thia-4-azaspiro[4.5]dec-3-ene, obtained from a solvate of sodium cyanodithioformate with three molecules of dimethylformamide, acetone, or cyclohexanone in the presence of morpholine, react with chlorothioformic dimethylamide with the formation of 2,2-dimethyl-5-oxo-4-(dimethylaminothiocarbonylthio)-1,3-thiazoline and 2-oxo-3-(dimethylaminothiocarbonylthio)-1-thia-4-azaspiro[4.5]dec-3-ene, respectively, and during acidolysis by hydrochloric acid they are converted to 2,2-dimethyl-5-oxo-4-thiono-1,3-thiazolidine and 2-oxo-3-thiono-1-thia-4-azaspiro[4.5]decane. The latter compounds are facilely phosphorylated by dialkyl chlorophosphonates at the nitrogen atom. The reaction of the solvate of sodium cyanodithioformate with three molecules of dimethylformamide with chloroacetone in the presence of morpho-line occurs anomalously with the formation of cyanothioformic morpholide.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2590–2593, November, 1990.     

Reaction of 5-(1-bromo-2-aryl-vinyl)-3-methyl-4-nitro-isoxazoles and 1,3-dicarbonyl compounds

The preparation of E-5-(1-bromo-2-aryl-vinyl)-3-methyl-4-nitro-isoxazoles and their reaction with 1,3-dicarbonyl compounds to give cyclopropanes or dihydrofurans is described.