Synthesis of 5-Alkyl(aryl)-2-alkylsulfanyl(alkoxy)-4-hydroxy-6H-1,3-oxazin-6-ones

Alkyl carbamates and S-alkyl thiocarbamates react with substituted malonyl dichlorides in boiling benzene to give the corresponding 2,5-substituted 4-hydroxy-6H-1,3-oxazin-6-ones. The reaction of S-methyl thiocarbamate with unsubstituted malonyl dichloride in boiling diethyl ether or benzene leads to formation of S-methyl (3-methylsulfanylaminocarbonyl-3-oxopropionyl)thiocarbamate and is not accompanied by cyclization, whereas in boiling toluene 4-hydroxy-2-methylsulfanyl-6H-1,3-oxazin-6-one is obtained.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 3, 2005, pp. 468–472.Original Russian Text Copyright © 2005 by Lalaev, Yakovlev, Zakhs.     

Synthesen von Heterocyclen, 141. Mitt.: Zur Chemie der 1,3-Oxazinone

Zusammenfassung N-substituierte Diphenylacetamide reagieren mit monosubstituierten Malonylchloriden zu Derivaten des 1,3-Oxazin-4,6-dions. Diese lassen sich thermisch zu den isomeren Tetrahydropyridin-2,6-dionen umlagern.

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Syntheses of heterocycles, CXLI: Chemistry of 1.3-oxazinones

N-substituted diphenylacetamides react with monosubstituted malonyl chlorides to give 1.3-oxazine-4.6-diones. These compounds are thermically rearranged to yield the isomeric tetrahydropyridine-2.6-diones.

     

N-Acylation of 4-alkylidene-β-lactams: unexpected results

This paper describes the different reactivity of E- and Z-4-alkylidene-β-lactams in acylation reactions under basic conditions. The E isomer is readily acylated, whereas the Z reacted sluggishly rearranging to the corresponding oxazin-6-one. The N-acylation of Z isomers was successfully obtained with oxalyl- or malonyl chlorides in benzene at reflux.     

Synthese von basisch substituierten 2-Methyl-2,3-dihydro-benzo[b]thiophenen

N-substituted {2-methyl-benzo[b]thienyl-(3)}-acetamides were oxidized to the corresponding 1,1-dioxides, catalytic hydrogenation of which gave N-substituted {2-methyl-2,3-dihydro-benzo[b]thienyl-(3)}-acetamide-S,S-dioxides. The latter were reduced by LiAlH₄ to give N-substituted 2-methyl-3-(β-amino-ethyl)-2,3-dihydro-benzo[b]thiophenes.     

Cyclopropanation of N-substituted 3-aryl-2-cyanoprop-2-enamides and derivatives of 5,5-Dimethyl-2-oxo-2,5-dihydrofuran-3-carboxylic acid and 2-oxochromene-3-carboxylic acid with bromine-containing zinc enolates

Zinc enolates derived from 1-aryl-2,2-dibromoalkanones react with N-substituted 3-aryl-2-cyanoprop-2-enamides and 5,5-dimethyl-2-oxo-2,5-dihydrofuran-3-carboxylic and 2-oxochromene-3-carboxylic acid derivatives to give, respectively, N-substituted 2-alkyl-3-aryl-2-aroyl-1-cyanocyclopropane-1-carboxamides, 6-(4-bromobenzoyl)-4,4,6-trimethyl-2-oxo-3-oxabicyclo[3.1.0]hexane-1-carboxylic acid ethyl ester and morpholide, and 1-alkyl-1-aroyl-2-oxo-1a,7b-dihydrocyclopropla[c]chromene-1a-carboxylic acids as a single geometric isomer. Treatment of 1-alkyl-1-aroyl-2-oxo-1a,7b-dihydrocyclopropa[c]chromene-1a-carboxylic acids with carboxylic acid anhydrides leads to the formation of the corresponding 9c-alkyl-1-aryl-3,4-dioxo-9b,9c-dihydro-2,5-dioxacyclopenta[2,3]cyclopropa[1,2-a]naphthalen-1-yl carboxylates.     

Five-membered 2,3-dioxo heterocycles: LXIII. Cascade recyclization of isopropyl 2-(1-aryl-4,5-dioxo-2-phenyl-4,5-dihydro-1H-pyrrol-3-yl)-2-oxoacetates with cyclic enamines. Crystalline and molecular structure of 1′-benzyl-6′,6′-dimethyl-3-[(Z)-phenyl(phenylamino)methylidene]-6′,7′-dihydro-3H-spiro[furan-2,3′-indole]-2′,4,4′,5(1′H,5′H)-tetraone

Isopropyl 2-(1-aryl-4,5-dioxo-2-phenyl-4,5-dihydro-1H-pyrrol-3-yl)-2-oxoacetates reacted with N-substituted 3-amino-5,5-dimethylcyclohex-2-en-1-ones to give the corresponding 1′-substituted (Z)-6′,6′-dimethyl-3-[phenyl(arylamino)methylidene]-6′,7′-dihydro-3H-spiro[furan-2,3′-indole]-2′,4,4′,5(1′H,5′H)-tetraones. The structure of 1′-benzyl-6′,6′-dimethyl-3-[(Z)-phenyl(phenylamino)methylidene]-6′,7′-dihydro-3Hspiro[furan-2,3′-indole]-2′,4,4′,5(1′H,5′H)-tetraone was proved by X-ray analysis.     

Reaction of N-substituted 2-oxochromen-3-carboxamides with bromoderivatives of zinc enolates prepared from alkyl 2,2-dialkyl-4,4-dibromo-3-oxoalkanoates and zinc

Zinc enolates obtained from ethyl 2,2-dialkyl-4,4-dibromo-3-oxobutanoates and zinc react with N-substituted 2-oxochromen-3-carboxamides forming ethyl 3-{1a-(R³-carbamoyl)-2-oxo-1a,7b-dihydrocyclopropa[c]chromen-1-yl}-2,2-dialkyl-3-oxopropanoate isomer with a Z-position of methine hydrogens. Zinc enolates prepared from alkyl 2,2-dialkyl-4,4-dibromo-3-oxopentanoates and-hexanoates and zinc react with N-substituted 2-oxochromen-3-carboxamides to give rise to esters of 3-{1-alkyl-1a-(R³-carbamoyl)-2-oxo-1a,7b-dihydrocyclopropa-[c]chromen-1-yl}-2,2-dialkyl-3-oxopropanoic acid as isomers with the E-position of the methine proton and the alkyl substituent. The reaction carried out in the presence of small quantities of THF and HMPA leads to the formation of 9c-alkyl-2-R³-9b,9c-dihydro-5-oxa-2-azacyclopenta[2,3]-cyclopropa[1,2-a]naphthalene-1,3,4-triones. Zinc enolates from alkyl 2,2-dialkyl-4,4-dibromo-3-oxopentanoates and-hexanoates and zinc with the secondary amides of 2-oxochromen-3-carboxylic acid form alkyl 3-{2-oxo-1a-(piperidinocarbonyl)-and 3-{6-R¹-1a-(morpholinocarbonyl)-2-oxo-1a,7b-dihydrocyclopropa[c]chromen-1-yl}-2,2-R²,R²-3-oxopropanoates as single geometrical isomers.     

Synthesis of epoxy and aziridino malonyl peptidomimetics

Short malonyl dehydro peptides have been epoxidized using H₂O₂/Na₂WO₄ dihydrate. The obtained diastereomeric epoxides were separated by HPLC and successfully tested in the ring opening reaction with N-Boc l-cysteine methyl ester, to indicate their electrophilic behavior. Moreover, by a simple two-step reaction, the epoxy malonyl peptides can be converted into the corresponding aziridino malonyl peptides.     

Benzylic Newman-Kwart rearrangement of O-azidobenzyl thiocarbamates triggered by phosphines: pseudopericyclic [1,3] shifts via uncoupled concerted mechanisms

A series of O-(o- and p-azido)benzyl thiocarbamates smoothly rearranged in the course of Staudinger imination reactions with tertiary phosphines, giving rise to the respective S-(o- and p-phosphinimino)benzyl thiocarbamates as a result of an oxygen to sulfur migration of the functionalized benzyl group. By contrary, their m-azido isomers did not rearrange under similar conditions. Computational investigations using DFT methods revealed the uncoupled concerted mechanisms of these 1,3-benzyl shifts via polar transition states with pseudopericyclic orbital topologies, with the benzyl group migrating in the plane of the thiocarbamate fragment.     

Synthesis of piperidine derivatives fused to a tetrahydrofuran ring

Intramolecular nucleophilic opening of the oxirane ring in tert-butyl 6-(2-hydroxyethyl)-7-oxa-3-azabicyclo[4.1.0]heptane-3-carboxylate by the action of excess potassium hydroxide in 75% aqueous dimethyl sulfoxide at 110–120°C gave tert-butyl (3aR,7aS)-3a-hydroxyhexahydrofuro[2,3-c]pyridine-6(2H)-carboxylate whose treatment with POCl₃ resulted in elimination of water molecule and tert-butoxycarbonyl group with formation of 2,3,4,5,6,7-hexahydrofuro[2,3-c]pyridine hydrochloride. The latter reacted with electrophiles (acetic anhydride, methanesulfonyl chloride, and benzaldehyde in combination with sodium triacetoxyhydridoborate) in the presence of triethylamine, yielding the corresponding N-substituted 2,3,4,5,6,7-hexahydrofuro[ 2,3-c]pyridine derivatives.     

Quantum-Chemical Study of the Relative Stability of N-Substituted Tetrazole Isomers

The enthalpies of formation and total energies of a series of 1- and 2-substituted tetrazoles in the gas phase and in solution were calculated by MNDO and AM1 semiempirical methods and by a set of nonempirical procedures. The effect of solvent on the relative stability of N-substituted tetrazoles was estimated in terms of the PCM, SM5, and SCRF models. The possibility for isomerization of N-substituted tetrazoles, depending on the substituent in position 1 or 2, was studied at the MP2/6-31G*//HF/6-31G* level. According to the results of nonempirical calculations, 2-substituted tetrazoles are more stable in the gas phase, in keeping with the experimental data for the corresponding isomers. The solvent nature is an important factor affecting isomerization of N-substituted tetrazoles: Rise in the solvent polarity leads to displacement of the equilibrium toward 1-substituted isomers.     

Synthesis and Properties of sym-Triazine Derivatives. 18. Synthesis of N-Substituted 2,4-Diamino-6-(benzothiazolyl-2-thiomethyl)-sym-triazines

The condensation of methyl benzothiazolyl-2-thioacetate with N-substituted biguanides in the presence of sodium methylate gave 2-amino-4-(RR'-amino)-6-(benzothiazolyl-2-thiomethyl)-sym-triazines. In a number of cases the 1,1-disubstituted 5-(benzothiazolyl-2-thioacetyl)biguanides could also be separated and these could be cyclized by refluxing in DMF to the corresponding substituted sym-triazines described. The latter type of compound was also synthesized by treating 2-amino-4-trichloromethyl-6-(benzothiazolyl-2-thiomethyl)-sym-triazine with primary and secondary aliphatic and heterocyclic amines or by the reaction of N-substituted 2,4-diamino-6-chloromethyl-sym-triazines with 2-mercaptobenzothiazole.     

Electron impact ionization mass spectrometry and intramolecular cyclization in 2-substituted pyrimidin-4(3H)-ones

Electron impact ionization mass spectrometry indicates that the behavior of W-unsubstituted pyrirnidin-4-ones with CH₂-R type substitution at C-2 differs from homologs that are N-substituted and/or 2-aryl- or 2-methyl-substituted. A dominant intramolecular cycliza-tion was found to occur between 3ZV (in agreement with the predominance of the 3NH tautomers) and the ortho positions of the aryl moiety in compounds with a CH₂-aryl substitution at C-2. Theoretical calculations with an AMI SCFR method on 2-, 6-, and 2, 6-disubstituted pyrimidin-4-ones support the mass spectrometric observations.     

Synthesis of new acyl, furoyl, and benzoylthiocarbamates as polydentate systems. Structural study of isopropyl N-(2-furoyl)thiocarbamate

Synthesis of new acylthiocarbamates has been carried out. To establish the preferential conformation and to explain the behaviour chemically, the structure of isopropyl N-(2-furoyl)thiocarbamate 3m has been determined by single-crystal X-ray analysis. The most stable conformation E,Z′ established by X-ray analysis was corroborated by semiempirical theoretical calculations.     

Kinetics of the thermal decomposition of ammonium thiocarbamate

Results of the kinetic study of the thermal decomposition of ammonium thiocarbamate in vacuum (ca. 10^?2 torr) in the temperature range 303–353 K are presented. Under these conditions ammonium thiocarbamate decomposes into gaseous products (NH₄COSNH₂→2 NH₃ + COS). Fifteen general equations for the kinetics of thermal decomposition of solids were taken into consideration. The following equation describes the experimental results over the whole range of the degree of decomposition: $$\alpha = \frac{{2k_2 }}{{ab}}(t - t_0 )[a + b - 2k_2 (t - t_0 )]$$ whereα=degree of decomposition,t=time,t ₀=time required to attain constant growth rate of nuclei, anda andb are the dimensions of the crystal. The temperature-dependence of the rate constantk ₂ was determined and the activation energy was found to be 10.7 kcal/mole. An experiment planning scheme was adopted in this study: in a series of experiments, each one was followed by statistical analysis in order to plan successive experiments depending on the results of the previous one.     

Inhibitor Ionization as a Determinant of Binding to 3-Dehydroquinate Synthase

Phosphinomethyl and carboxymethyl monoacids along with succinyl, malonyl ether, malonyl, and hydroxymalonyl diacids were substituted for phosphorylmethyl, phosphonoethyl, and phosphonomethyl groups in carbocyclic inhibitors of DHQ synthase. All but one of the carbocyclic inhibitors were synthesized via intermediacy of a 2,3-butane bisacetal-protected 3-dehydroquinic acid. Carbaphosphinate (K(i) = 20 x 10(-)(6) M) was a modest competitive inhibitor of DHQ synthase, while carbaacetate was a linear mixed-type inhibitor (K(i) = 3 x 10(-)(6) M, K(i)' = 20 x 10(-)(6) M). Carbasuccinate (K(i) = 5 x 10(-)(6) M), carbamalonate ether (K(i) = 7 x 10(-)(6) M), carbamalonate (K(i) = 0.7 x 10(-)(6) M), and carbahydroxymalonate (K(i) = 0.3 x 10(-)(6) M) were all competitive inhibitors. Carbaacetate was the only inhibitor that was not oxidized by DHQ synthase. On the basis of these data, carbocyclic inhibitors with malonyl and hydroxymalonyl groups are apparently bound by DHQ synthase as tightly as carbocyclic inhibitors possessing phosphorylmethyl and phosphonoethyl moieties.     

The preparation of N-substituted aminomethylidenebisphosphonates and their tetraalkyl esters via reaction of isonitriles with trialkyl phosphites and hydrogen chloride. Part 1

The reaction of isonitriles with trialkyl phosphites in the presence of hydrogen chloride gives tetraalkyl N-substituted aminomethylidenebisphosphonates via N-methylideneaminium (isonitrilium) salts. Hydrolysis or dealkylation of these tetraalkyl esters gives N-substituted aminomethylidenebisphosphonic acids in high yields.     

Modification of biologically active amides and amines with fluoro-containing heterocycles 5. Fluoro-containing heterocyclic derivatives of 2-amino-1,3,4-thiadiazoles

An approach to modification of biologically active 2-amino-1,3,4-thiadiazoles with fluoro-containing five-membered heterocycles was proposed. The approach involves reactions of imines (generated in situ from 2-amino-1,3,4-thiadiazoles and methyl trifluoropyruvate) with 1,3-binucleophiles such as 6-aminouracils, 6-aminothiouracils, N-substituted 3-aminocyclohexenones, N-substituted ureas, N-substituted benzamidines, and 3-aminocrotononitrile.     

Asymmetric α-2-tosylvinylation of in situ-generated N-2-tosylvinyl proline-derived ammonium ylides

Asymmetric α-2-tosylvinylation of N-substituted proline esters using ethynyl tolyl sulfone as an electrophile was shown to proceed in good yield with high enantioselectivities without the addition of any bases. The reaction proceeds via the formation of N-2-tosylvinyl ammonium ylides.     

Synthesis of bisarylmethyl-substituted pyrimidines and quinolines

The condensation of 2-chloro-8-methylquinoline-3-carbaldehyde, 2-chloroand 2-chloro-7,8,9,10-tetrahydrobenzo[h]quinoline-3-carbaldehydes, 2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-carbaldehyde, 6-methyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-carbaldehyde, and 2-chloropyrido[1,2-a]pirimidine-3-carbaldehyde with N-substituted anilines gave the corresponding diaryl(hetaryl)methanes.