A convenient synthesis of 1,3-oxazolidin-4-ones and 1,3-oxazin-4-ones

1,3-Oxazolidin-4-ones and 1,3-oxazin-4-ones were synthesized by formal cyclocondensation of imines with α- or β-hydroxy acids.     

Synthesis of 4H-1,3-benzoxazin-4-onium salts and 4-H-1,3-benzoxazin-4-ones

Salicylamide and its substituted derivatives react with aliphatic carboxylic acid anhydrides and perchloric acid to give 4H-1,3-benzoxazin-4-onium salts. These same compounds were obtained by acidic cyclization of O- and N-acylsalicylamides. The synthesized salts are converted to 2-substituted 4H-1,3-benzoxazin-4-ones by the action of triethylamine and are hydrolyzed by water to N-acylsalicylamides. The probable reaction scheme is examined.     

Synthesis of 2-aryl-4-azaindan-1,3-diones and 2-aryl-4-aza-5,6-benzindan-1,3-diones

Condensation of 2-hydroxymethylnicotinic and 2-hydroxymethylquinoline-3-carboxylic acid lactones with aromatic aldehydes in the presence of sodium methoxide gives, respectively, 2-aryl-4-azaindan-1,3-diones and 2-aryl-4-aza-5,6-benzindan-1,3-diones. Alkylation of 2-aryl-4-azaindan-1,3-diones with diazomethane gives the N-methylbetaines. According to the IR spectra, in the solid state the 4-azaindan-1,3-diones seemto have a strongly polarized enol structure.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 5, pp. 647–650, May, 1970.     

Synthesis of 4-alkoxy-4-methyl- and 4-alkoxy-4-fluoromethyl-1,3-benzoxazinones

Cyclization of 2-hydroxyacetophenone hydrazones with triphosgene resulted in the formation of 4-methylene-1,3-benzoxazinones. These compounds were converted to 4-alkoxy-4-methyl-1,3-benzoxazinones and 4-fluoromethyl-4-methoxy-1,3-benzoxazinones upon treatment with alcohols under refluxing conditions and F-TEDA-BF₄ in acetonitrile and methanol, respectively.     

Zur Synthese sulfonierter Derivate von 4-Amino-1,3-dimethylbenzol und 2-Amino-1,3-dimethylbenzol

Syntheses of Sulfonated Derivatives of 4-Amino-1, 3-dimethylbenzene and 2-Amino-1, 3-dimethylbenzene Direct sulfonation of 4-amino-1, 3-dimethylbenzene (1) and sulfonation of 4-nitro-1,3-dimethylbenzene ( 4 ) to 4-nitro-1,3-dimethylbenzene-6-sulfonic acid ( 3 ) followed by reduction yield 4-amino-1,3-dimethylbenzene-6-sulfonic acid ( 2 ). The isomeric 5-sulfonic acid ( 5 ) however is prepared solely by baking the acid sulfate salt of 1 . Reaction of sulfur dioxide with the diazonium chloride derived from 2-amino-4-nitro-1,3-dimethylbenzene ( 7 ) leads to 4-nitro-1,3-dimethylbenzene-2-sulfonyl chloride ( 8 ), which is successively hydrolyzed to 4-nitro-1,3-dimethylbenzene-2-sulfonic acid ( 9 ) and reduced to 4-amino-1, 3-dimethylbenzene-2-sulfonic acid ( 6 ). Treatment of 4-amino-6-bromo-1,3-dimethylbenzene ( 12 ) and 4-amino-6-chloro-1, 3-dimethylbenzene ( 13 ), the former obtained by reduction of 4-chloro-6-nitro-1,3-dimethyl-benzene ( 10 ) and the latter from 4-chloro-6-nitro-1, 3-dimethylbenzene ( 11 ), with oleum yield 4-amino-6-bromo-1,3-dimethylbenzene-2-sulfonic acid ( 14 ) and 4-amino-6-chloro-1,3-dimethylbenzene-2-sulfonic acid ( 15 ) respectively; subsequent carbon-halogen hydrogenolyses of 14 and 15 lead also to 6 (Scheme 1). Baking the acid sulfate salt of 2-amino-1, 3-dimethylbenzene ( 17 ) gives 2-amino-1, 3-dimethylbenzene-5-sulfonic acid ( 16 ), whereas the isomeric 4-sulfonic acid ( 18 ) can be prepared by either of the following three possible pathways: Sulfonation of 2-nitro-1,3-dimethylbenzene ( 20 ) to 2-nitro-1,3-dimethylbenzene-4-sulfonic acid ( 21 ) followed by reduction or sulfonation of 2-acetylamino-1,3-dimethylbenzene ( 19 ) to 2-acetylamino-1,3-dimethylbenzene-4-sulfonic acid ( 22 ) with subsequent hydrolysis or direct sulfonation of 17 . Further sulfonation of 18 yields 2-amino 1,3-dimethylbenzene-4,6-disulfonic acid ( 23 ), the structure of which is independently confirmed by reduction of unequivocally prepared 2-nitro- 1,:3-dimethylbenzene-4,6-disulfonic acid ( 24 )(Scheme 2).     

Bildung von 5,6-Dihydro-1,3(4H)-thiazin-4-carbonsäure-estern aus 4-Allyl-1,3-thiazol-5(4H)-onen

Formation of Methyl 5,6-Dihydro-l, 3(4H)-thiazine-4-carboxyiates from 4-Allyl-l, 3-thiazol-5(4H)-ones . The reaction of N-[1-(N, N-dimethylthiocarbamoyl)-1-methyl-3-butenyl]benzamid ( 1 ) with HCl or TsOH in MeCN or toluene yields a mixture of 4-allyl-4-methyl-2-phenyl-1,3-thiazol-5(4H)-one ( 5a ) and allyl 4-methyl-2-phenyl-1,3-thiazol-2-yl sulfide ( 11 ; Scheme 3). Most probably, the corresponding 1,3-oxazol-5(4H)-thiones B are intermediates in this reaction. With HCl in MeOH, 1 is transformed into methyl 5,6-dihydro-4,6-dimethyl-2-phenyl-1,3(4H)-thiazine-4-carboxylate ( 12a ). The same product 12a is formed on treatment of the 1,3-thiazol-5(4H)-one 5a with HCl in MeOH (Scheme 4). It is shown that the latter reaction type is common for 4-allyl-substituted 1,3-thiazol-5(4H)-ones.     

Intermolecular 1,3-dipolar cycloaddition of benzonitrile oxide to 2H-1,3-benzothiazines and hexahydro-4H-1,3-benzothiazine

The thermal [3 + 2] intermolecular cycloaddition of benzonitrile oxide to 2H-1,3-benzothiazines 1a-g and hexahydro-4H-1,3-benzothiazine ( 5 ) gives new types of tricyclic angularly and linearly condensed 1,2,4-oxadiazolo-1,3-benzothiazine-fused nitrogen-bridgehead ring systems 2a-g, 6 .     

Diels-Alder-Reaktionen mit aktivierten 4-Methyl-1,3-pentadienen

Diels-Alder Reactions with Activated 4-Methyl-1,3-pentadienes Ethyl 4-methyl-1,3-pentadienyl ether, trimethyl[(4-methyl-1,3-pentadienyl)oxy]silane, and 1-(4-methyl-1,3-pentadienyl)pyrrolidine and the corresponding piperidine analogue have been used in Diels-Alder reactions with acrylonitrile, ethyl acetylenedicarboxylate, maleic anhydride, and 2,6-dimethyl-p-benzoquinone.     

Solid-state structures of 2-(4-hydroxyphenyl)-substituted phenalene-1,3-dione and indan-1,3-dione

The structure of 2-(4-hydroxyphenyl)-substituted indan-1,3-dione and phenalene-1,3-dione is investigated using a combination of solid-state NMR, single crystal X-ray analyses and quantum chemical calculations. It is shown that 2-(4-hydroxyphenyl)-1,3-indandione exists as a diketo tautomer while 2-(4-hydroxyphenyl)-1,3-phenalenedione exists in the enol form.     

Diastereoselective cycloadditions of 1,3-thiazolium-4-olates with chiral 1,2-diaza-1,3-butadienes

A series of 2-(N-methyl)benzylamino-1,3-thiazolium-4-olates (2-aminothioisomunchnones) react with chiral 1,2-diaza-1,3-butadienes derived from carbohydrates to afford a diastereomeric mixture of (4R,5S)- and (4R,5R)-4,5-dihydrothiophenes. These substrate-controlled cycloadditions are chemoselective, regiospecific, and proceed with a high facial diastereoselection. A theoretical rationale at semiempirical level does justify the stereochemical outcome observed in the experiments.     

2-Aryl-4-azaindain-1,3-diones

2-Pheny1-4-azaindan-1,3-dione and 2-(p-dimethylaminophenyl)-4-azaindan-1,3-dione are synthesized by condensing 4-azaphthalide with benzaldehyde and p-dimethylaminobenzaldehyde. 4-Azaphthalide reacts with p-nitrobenzaldehyde in hot acetic anhydride to give 3-(p-nitrobenzylidene)-4-azaphthalide, rearranged by sodium methoxide to 2-(p-nitrophenyl)-4-azaindan-1,3-dione. 2-Phenyl-and 2-(p-nitrophenyl)-4-azaindandiones are also obtained by sodium methoxide rearrangement of the products of reaction of quinolinic anhydride with phenylacetic and p-nitrophenylacetic acids. 2-Aryl-4-azaindandiones are deeply colored substances only slightly soluble, and without sharp melting points. They undergo methylation at the nitrogen atom, to give N-methylbetaines. The IR absorption spectra show that 2-ary]-4-azaindandiones exist in a strongly polarized enol form in the solid state.     

Synthesis of N-substituted 4-aminomethyl-1,3-dioxanes

4-(R-Amino)methyl-1,3-dioxanes were synthesized from 4-chloromethyl-1,3-dioxanes. Some of these products were converted into water-soluble pyridinium chlorides by consecutive treatment with chloroacetyl chloride and pyridine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 21–23, January, 1995.     

N-(1,3-Thiazol-5(4H)-yliden)amine aus 1,3-dipolaren Cycloadditionen von Aziden mit 1,3-Thiazol-5(4H)-thionen

N-(1,3-Thiazol-5(4H)-ylidene)amines via 1,3-Dipolar Cycloaddition of Azides and 1,3-Thiazol-5(4H)-thiones Organic azides 5 and 4,4-dimethyl-2-phenyl-1,3-thiazol-5(4H)-thione ( 2 ) in toluene at 90° react to give the corresponding N-(1,3-thiazol-5(4H)-ylidene)amines (= 1,3-thiazol-5(4H)-imines) 6 in good yield (Table). A reaction mechanism for the formation of these scarcely investigated thiazole derivatives is formulated in Scheme 3: 1,3-Dipolar azide cycloaddition onto the C?S group of 2 leads to the 1:1 adduct C . Successive elimination of N₂ and S yields 6 , probably via an intermediate thiaziridine E .     

One-step synthesis of some polyfluoroalkylated 1,3-benzodioxoles, 4H-1,3-benzodioxins and dibenzo[d,f] [1,3]dioxepins

Several polyfluoroalkylated heterocyclic compounds containing methylenedioxy group such as 2-(F-alkyl) substituted 1,3-benzodioxole, piperonal, 4H-1,3-benzodioxin, 1,3-dioxolane and 6-(F-alkyl) substituted dibenzo[d, f][1,3]dioxepin have been prepared through double Michael-addition reactions of 2,2-dihydropolyfluoroalkanoates with the corresponding diphenols or diols in high yields.     

Regioselektive 1,3-dipolare Cycloadditionen von Thiocarbonyl-yliden mit 1,3-Thiazol-5(4H)-thionen

Regioselective 1,3-Dipolar Cycloadditions of Thiocarbonyl Ylides with 1,3-Thiazole-5(4H)-thiones The thiocarbonyl ylides 13 and 1,3-thiazol-5(4H)-thiones 1 undergo a smooth reaction to yield spirocyclic 1,3-dithiolanes 14 – 16 (Schemes 4–6). The 1,3-dipolar cycloadditions occur in a regioselective manner, but the orientation of the thiobcnzophenone-S-methylide ( 13b ) differs from that of the cycloalkane thione-S-methylides 13a and 13c . Whereas the 1,3-cycloadduct with 13b is formed in accordance with frontier-orbital considerations, the inverse orientation in the reactions with 13a and 13c most likely is the result of steric hindrance in the transition state. The thiocarbonyl ylides have been prepared in situ from the corresponding 2,5-dihydro-1,3,4-thiadiazoles 12 . The more stable aliphatic precursors 12a and 12c undergo decomposition at 50°, the unstable 12b at ?30°.     

Synthesis of substituted 2-amino-5,6-dihydro-4h-1,3-oxazines and 2-iminotetrahydro-1,3-oxazines

3,4,4,6-Tetramethyl-2-aryliminotetrahydro-1,3-oxazines were synthesized by intramolecular cyclization of N-aryl-N′-methyl-N′-(2-methyl-4-hydroxy-2-pentyl)-S-methylisothioureas. 4,4,6-Trimethyl-2-(N-methyl-N-arylamino)-5,6-dihydro-4H-1,3-oxazines were obtained by methylation of 4,4,6-trimethyl-2-arylamino-5,6-dihydro-4H-1,3-oxazines.     

Synthesis of 2-ferrocenylidene-4-cyclopentene-1,3-diones

A squarate-based synthesis of 2-ferrocenylidene-4-cyclopentene-1,3-diones is described. When refluxed in dioxane at 100 °C, heated with silica gel as a solvent free grinded solid mixture at 125 °C or stirred with silica gel in ethyl acetate at room temperature, 4-ferrocenylethynyl-4-hydroxy-2-cyclobutenones, prepared from ethynylferrocene and 3-cyclobutene-1,2-diones, afforded 2-ferrocenylidene-4-cyclopentene-1,3-diones as the major or single product of the reaction. In some cases, ferrocenyl quinones also resulted from these reactions as the minor products. The major or exclusive formation of 2-ferrocenylidene-4-cyclopentene-1,3-diones is attributed to the radical-stabilizing ability of the ferrocenyl group.     

Synthesis of mono- and 1,3-diaminocalix[4]arenes via Ullmann-type amination and amidation of 1,3-bistriflate esters of calix[4]arenes

Practical methods are described for the preparation of monoamines 4 and 1,3-diamines 5, bearing one or two amino group(s) instead of the hydroxy group(s) at the 28-position or at both the 26- and 28-positions of p-tert-butylcalix[4]arene (1a) and p-tert-butylthiacalix[4]arene (1b), via the Ullmann-type amination or amidation. Thus, the copper-catalyzed or mediated amination of the 1,3-bistriflate ester (2a) of 1a with benzylamine affords either mono(benzylamino) triflate 7a or 1,3-bis(benzylamine) 8 in a high yield, depending on the reaction conditions. On the other hand, the 1,3-bistriflate ester (2b) of 1b resists disubstitution and produces, under stoichiometric conditions, mono(benzylamino) triflate 7b. The disubstitution of 2b is achieved by amidation with tosylamide, giving 1,3-bis(tosylamide) 17b. The hydrogenolysis of the benzylamino moiety of 7a, followed by the hydrolysis of the Tf moiety, affords monoamine 4a, while the hydrogenolysis of 8 affords 1,3-diamine 5a. The amino moiety of 7b can be deprotected under acidic conditions to give, after hydrolysis, monoamine 4b. The hydrolysis of 17b affords 1,3-diamine 5b. The overall yields of compounds 4a, 4b, 5a, and 5b are 72%, 45%, 78%, and 24%, respectively, based on commercially available compounds 1 and are much higher than the ones previously reported in the literature.     

1,3-Dioxolan-4-ones and 1,3-oxathiolan-5-ones. Configuration of cis and trans isomers

The attempted acid-catalyzed azeotropic removal of water from a mixture containing lactamide and chloral in refluxing toluene lead to the elimination of ammonia; both cis- and trans-5-methyi-2-(trichloromethyl)-1,3-dioxolan-4-one were isolated. A number of 1,3-dioxolan-4-ones and 1,3-oxathiolan-5-ones were obtained by cyclodehydration of aldehydes with α-hydroxy- and α-mercapto-carboxylic acids in the presence of boron trifluoride etherate. Geometric isomers were separated, and their configurations were determined by nuclear magnetic resonance.     

1,3-Dimethoxy-1,3-dimethyl-1,3-diphenyl- and 1,3-dimethoxy-1,3-tetraphenyldisiloxanes: synthesis and structure

Russian Chemical Bulletin - 1,3-Dimethoxy- 1,3-dimethyl- 1,3-diphenyl- and 1,3-dimethoxy- 1,3-tetraphenyldisiloxanes were synthesized. Their structures were confirmed by IR and NMR spectroscopy....