Synthesis of Highly Functionalized Isoxazolinediones from One-pot Reaction of Alkylidene Meldrum ’s Acid with Alkyl Isocyanides in the Presence of Arylhydroxylamines

Alkyl isocyanides undergo a smooth reaction with alkylidene Meldrum’s acids in the presence of arylhydroxylamines to produce N ¹-alkyl-2-(3,5-dioxo-2-aryltetrahydro-4-isoxazolyl)alkanamides in high yields.     

Synthesis of Highly Functionalized Isoxazolinediones from One-pot Reaction of Alkylidene <Emphasis Type="Italic">Meldrum</Emphasis>’s Acid with Alkyl Isocyanides in the Presence of Arylhydroxylamines

Summary. Alkyl isocyanides undergo a smooth reaction with alkylidene Meldrum’s acids in the presence of arylhydroxylamines to produce N ¹-alkyl-2-(3,5-dioxo-2-aryltetrahydro-4-isoxazolyl)alkanamides in high yields.     

Synthesis and exchange reactions of 5-alkyl-2-oxo-6-thioxo-1,2,3,6-hexahydropyrimidine-4-carboxylic acids

An improved preparation of 2-oxo-6-thioxo-1,2,3,6-hexahydropyrimidine-4-carboxylic acid 3, a potent inhibitor of dihydroorotase is presented. Trans-5-alkyl-2-oxo-6-thioxohexahydropyrimidine-4-carboxylic acids 12a-c were synthesised via the thiation of the p-methoxybenzyl esters of 5-alkyldihydroorotic acids with Lawesson's reagent followed by subsequent de-protection. The corresponding cisisomers were prepared by reduction of 5-alkyl-6-thioxoorotic acids with zinc in acetic acid. The stability and exchange reactions of 12a-c under physiological conditions were investigated by ultra-violet and ¹H nmr spectroscopy. The attempted synthesis of 16 , a fused cyclopentyl derivative of 3 is also presented.     

Homopolymerization of 2-alkyl- and 2-aryl-2-oxazolines

2-Aryl- and 2-alkyl-2-oxazolines have been polymerized to poly-(N-aroyl)aziridines and poly(N-acyl)aziridines, respectively, in the presence of boron trifluoride. The polymers obtained were glassy, light yellow resins with molecular weights ranging from 3500 to 7500 (35–50 oxazoline units per chain). The polymerization rates have been determined for several of these monomers. A polymerization mechanism is proposed.     

Synthesis of 5-alkyl-1,3,5-triazinan-2-ones and 5-alkyl-1,3,5-triazinane-2-thiones using Cu- and Sm-containing catalysts

Efficient procedures have been developed for the synthesis of 5-alkyl-1,3,5-triazinan-2-ones and 5-alkyl-1,3,5-triazinane-2-thiones by reaction of urea (thiourea) with primary alkylamines and N,N,N′,N′-tetramethylmethylenediamine and by reaction of primary amines with N,N′-bis(dimethylaminomethyl)urea(thiourea) in the presence of Cu- and Sm-containing catalysts.     

Conformational analysis of 2-methyl-5-alkyl- and 5-aryl-1,3,2-dioxaborinanes

Quantum chemical study of conformational isomerization of 2-methyl-5-alkyl- and 5-aryl-1,3,2-dioxaborinanes using RHF/6-31G(d) method led to the conclusion that the equilibrium between equatorial and axial sofa conformers is shifted to the latter form. Based on the experimental and theoretically calculated vicinal coupling constants J _HH the quantitative conformational composition and the values of ΔG ⁰ for substituents at the C⁵ ring atom were established.     

Dioxomolybdenum(VI) complexes containing 1-alkyl-2-ethyl-3-hydroxy-4-pyridin-4(1H)-ones

Dioxomolybdenum(VI) complexes derived from ethyl maltol (2-ethyl-3-hydroxy-4-pyrone) and 1-alkyl-2-ethyl-3-hydroxy-4-pyridin-4(1H)-ones have been prepared and characterized using physical methods including ¹H- and ¹³C-n.m.r. spectroscopy, i.r., elemental analysis, and X-ray diffraction for the pyrone and 3-methylpyridine pyridinone derivatives. The octahedral complexes have the general formula cis-MoO₂L₂ where L = the deprotonated pyrone or pyridinone ligand.     

Iron(II) complexes of 2,6-bis(5-alkyl-1,5-dimethyl-4,5-dihydro-1H-imidazol-4-on-2-yl)pyridine ligands. Synthesis, characterisation and solvolytic stability

New 2,6-bis(5-alkyl-1,5-dimethyl-4,5-dihydro-1H-imidazol-4-on-2-yl)pyridines have been prepared and characterized by ¹H-, ¹³C-NMR and elemental analysis. These ligands form complexes with FeCl₂, which were isolated and characterized by elemental analysis and MS. Both in the solid phase and in aqueous and methanolic solutions the complexes have two ligand molecules per one ferrous ion. By means of the kinetic stopped-flow method, the rate constants of acid catalyzed decomposition, which proceeds as a system of two consecutive reactions, were determined. It was found that increasing steric demands of 5-alkyl substituent in the 4,5-dihydro-1H-imidazol-4-one cycle significantly retards the acid catalyzed solvolysis. The methyl derivative is solvolyzed cca two orders faster than the corresponding t-Bu derivative.     

Synthesis and photochromic properties of N 2-alkyl-5-furyl-4-thienylpyridazinones

New dihetarylethenes containing the six-membered bridging moiety, viz., N ²-alkyl-5-furyl-4-thienylpyridazinones, were synthesized. These compounds have photochromic properties in solution. The hindered rotation of the thiophene and furan rings around the single bonds that link these rings to the double bond of the pyridazinone moiety results in the formation of mixtures of chiral diastereomers in solution, the lifetimes of the diastereomers being no longer than 0.2 s. The photochromic rearrangement of pyridazinones is characterized by the highly efficient photocoloration and the photobleaching, which is an order of magnitude less efficient, in the absence of thermal relaxation processes.     

A convenient synthesis of 3-alkyl-2,3-dihydro-2,4-dioxo-6-phenyl-, 3-alkyl-2,3-dihydro-4-oxo-6-phenyl-2-thioxo-, and 3-alkyl-2-arylimino-2,3-dihydro-4-oxo-6-phenyl-4H-1,3-thiazines

The reactions of 1-alkylamino-1-alkylthio-3-phenylpropene-3-thiones 3 with thiophosgene and phosgene in toluene, followed by treatment of the reaction mixture with triethylamine gave 3-alkyl-2,3-dihydro-4-oxo-6-phenyl-2-thioxo- 4 , 3-alkyl-2,3-dihydro-2,4-dioxo-6-phenyl-4H-1,3-thiazines 5 , respectively in good to excellent yields. Similarly treatment of compounds 3 with N-arylimidoyl dichloride in benzene at room temperature gave 3-alkyl-2-arylimino-2,3-dihydro-4-oxo-6-phenyl-4H-1,3-thiazines 6 in excellent yields. The reactions of compounds 3 with oxalyl chloride in toluene gave also 5 in good yields.     

Phase-transfer catalysis in reactions of 5-alkyl-3H-furan-2-ones with dichlorocarbene

Treatment of 5-alkyl-3H-furan-2-ones and 5-alkyl-3H-thiophen-2-ones with dichlorocarbene under conditions of phase-transfer catalysis at 20–90 °C results in insertion of the carbene at the C=C bond followed by skeletal rearrangement.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1995–1997, October, 1995.     

An efficient synthesis of 4-alkyl-2(1H)-quinazolinones and 4-alkyl-2-chloroquinazolines from 1-(2-alkynylphenyl)ureas

An efficient synthesis of 4-alkyl-2(1H)-quinazolinones has been achieved by cyclization of 1-(2-alkynylphenyl)ureas (2 R₂ = alkyl) in dichloroethane catalyzed by TfOH. In the case of aryl substitution (2 R₂ = aryl), a mixture of quinazolinone tautomers is obtained in dichloroethane with TFA as co-solvent. Chlorination of the resulting mixture affords 4-alkyl-2-chloro-quinazolines as sole products.     

A Convenient Synthesis of 2-Acyl-2-alkyl-3-nitro-2H-chromenes

Treatment of 2-hydroxybenzaldehydes by potassium t-butoxide in THF at 0°C, followed by addition of β-nitroenones 1 affords 2-acyl-2-alkyl-4-hydroxy-3-nitrochromanes 3. Subsequent treatment of these nitro alcohols by silica gel at 50°C leads to the desired 2-acyl-2-alkyl-3-nitro-2H-chromenes 4 in good yields.     

Synthesis and properties of 1-aryl-2-alkyl-1,4,5,6-tetrahydropyrimidines

A general method is described for the synthesis of 1-aryl-2-alkyl-1,4,5,6-tetrahydropyrimidines 1 , by cyclization of N-acyl-N′-aryltrimethylenediamines 2 with trimethylsilyl polyphosphate. Precursors 2 were obtained by aminolysis of the corresponding N-(3-bromopropyl)amides 3. The ¹H nmr spectra of tetrahydropyrimidines 1 are analyzed, discussing the influence of substituents in positions 1 and 2 of the heterocyclic ring. Alkaline hydrolysis of compounds 1 , which originates exclusively N-acyl-N′-aryltrimethylenediamines 2 , through an intermediate carbinolamine, was also studied. Cleavage of such an intermediate is discussed in the light of the stereoelectronic control theory. Reduction of compounds 1 with borane, leads regiospecifically to N-alkyl-N′-aryltrimethylenediamines 6.     

Synthesis of 2-alkyl-1,2,4-benzotriazin-3(2h)-ones and 2-alkyl-1,4-dihydro-1,2,4-benzotriazin-3(2h)-ones

A preparative method for the synthesis of 2-alkyl-1,2,4-benzotriazin-3(2H)-ones 3 was developed. The method involves treatment with sodium cyanate of 2-alkylbenzotetrazinium tetrafluoroborates, which exist in solutions in equilibrium with o-(alkylazo)aryldiazonium tetrafluoroborates. Reduction of compounds 3 with zinc in acetic acid afforded 2-alkyl-1,4-dihydro-1,2,4-benzotriazin-3(2H)-ones. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 346–349, February, 2006.     

Three-dimensional structures of 2-alkyl-4-formyltetrahydropyrans

The three-dimensional structures of a number of diastereomeric 2-alkyl-4-formyltetrahydropyrans were studied by means of ¹H and ¹³C NMR spectroscopy. It is shown that the 2,2-dialkyl derivatives are mixtures of two configurational isomers in which the formyl group is equatorially oriented. 2-Monoalkyl-4-formyltetrahydropyrans exist in the form of mixtures of two diastereomeric forms that have different orientations (axial and equatorial) of the formyl group; the alkyl group in both isomers is equatorially oriented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 311–314, March, 1979.     

Synthesis of some 2-alkyl-4-quinolone and 2-alkyl-4-methoxyquinoline alkaloids

Acid-catalyzed condensation of a series of 3-oxoalkanoic acid esters with aniline affords the corresponding 2-alkyl-4-quinolones in good yield. Treatment of these compounds with methyl iodide affords 2-alkyl-4-methoxyquinolines and 2-alkyl-N-methylquinolones. Three of the compounds are naturally-occurring alkaloids which are synthesized here for the first time.     

An efficient solid-phase synthesis of 2-alkyl-4,6-diaminopyrimidines and 2,4,6-triaminopyrimidines

An efficient and simple approach for the solid-phase synthesis of 2,4,6-triaminopyrimidines and 2-alkyl-4,6-diaminopyrimidines is described. Primary amines were immobilized on 2-(4-formyl-3-methoxyphenoxy)ethyl polystyrene resin via reductive amination. Attachment of two different 4,6-dichloropyrimidines led to the corresponding 4-chloro-6-aminopyrimidine intermediates. Aromatic nucleophilic substitution with various aliphatic amines or the corresponding lithium amides afforded the desired aminopyrimidines in high yield and excellent purity after acidic cleavage from the resin. The products were characterized by LC-MS, ¹H and ¹³C NMR spectroscopy. Deuterium exchange experiments revealed that the investigated aminopyrimidines have a general tendency toward C-5 protonation.     

Synthesis,structure, and photoluminescence properties of 4-methyl-<Emphasis Type="Italic">N</Emphasis>-{2-([1-alkyl-2-[2-(<Emphasis Type="Italic">p</Emphasis>-tolylsulfonylamino)phenyl]benzimidazol-5-yl]iminomethyl)phenyl}benzenesulfonamides and their zinc complexes

4-Methyl-N-{2-([1-alkyl-2-[2-(p-tolylsulfonylamino)phenyl]benzimidazol-5-yl]iminomethyl)phenyl}-benzenesulfamides (H₂L) and zinc complexes on their basis Zn₂L₂ have been synthesized. The structure of the ligands and complexes has been studied by IR, UV, ¹Н NMR spectroscopy, X-ray absorption spectroscopy, and X-ray diffraction analysis.     

Reactivity of 2-amino-1,3,4-thiadiazoles. Nucleophilic behaviour of some 2-amino-1,3,4-thiadiazoles: Model compounds

The ambident nucleophilic behaviour of some 2-amino-5-H-1,3,4-thiadiazoles in alkylation, acylation and nitrosation reaction has been verified. The structures assigned to the 2-amino-1,3,4-thiadiazoles ( 1a-i ) and to the Δ²-1,3,4-thiadiazolines ( 2a-e ) agree with the spectral data.