Theoretical investigation on conformational preferences and structural properties of 2-lithio-1,3-diphosphinane and 2-lithio-1,3-dimethyl-1,3-diphosphinane

A new family of dialphosphacyclohexane is introduced which has three nucleophilic centers. The conformational stabilities and structural properties of 2-lithio-1,3-diphosphinane and 2-lithio-1,3-dimethyl-1,3-diphosphinane were investigated computationally by DFT calculations and NBO analyses at B3LYP/6-31+G(d,p). Relative energy trend in 1,3-diphosphinane and 1,3-dimethyl-1,3-diphosphinane conformations explored from steric and hyperconjugative point of view. The stability trend of 2-lithio derivatives based on calculated relative energies in 1,3-diphosphinane is 1d > 1f > 1b > 1a > 1c > 1e and for 1,3-dimethyl-1,3-diphosphinane derivatives is 2f > 2d > 2b > 2a > 2c > 2e. Calculated NBO atomic charges indicate that high positive charge at lithium and small C–Li Wiberg bond indexes in these derivatives are demonstrators of ionic nature of the C–Li bonds. Stereoelectronic interactions, polarizability of phosphorus, and chelate formation between each of phosphorous and lithium are determining factors in stability trend observed in these derivatives. Ease of lithiation in bis(dimethylphosphino)methane, 1,3-diphosphinane, and 1,3-dimethyl-1,3-diphosphinane derivatives was estimated and compared by isodesmic reaction.     

Synthesis of 1,3-dihalo-1,3-dioximino-2-propanones

1,3-Dihalo-1,3-dioximino-2-propanones (Hal=Cl or Br), which had been difficult to prepare or unreported, were obtained by the nitrosation of 1,3-dihalo- and 1,3-dihalo-1-oximino-2-propanones by nitrosylsulfuric acid in concentrated H₂SO⁴.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 506–509, February, 1991.     

Photocyclization of 2-chloro-substituted 1,3-diarylpropan-1,3-diones to flavones

The photochemical behavior of 2-halo-substituted 1,3-diarylpropan-1,3-dione strongly depends on the nature of the halogen atom bonded and the presence of electron-donor groups on the phenyl ring. In the case of 2-chloro-1,3-diphenylpropan-1,3-dione and 1-(3,5-dimethoxyphenyl)-3-phenylpropan-1,3-dione, cyclization to flavones was the sole reaction pathway, whereas in the case of 2-chloro-1,3-di(4-methoxyphenyl)propan-1,3-dione, only products derived from alpha-cleavage were observed. 2-Fluoro derivatives of 1,3-diarylpropan-1,3-diones were photostable; on the other hand, 2-chloro-2-fluoro derivates resulted in 3-fluoroflavones.     

Cationic copolymerization of 2-vinyl-1,3-dioxane with styrene and 1,3-dioxolane

Copolymerization of 2-vinyl-1,3-dioxane with styrene and 1,3-dioxolane was carried out in methylene chloride at 0°C with triethyloxonium tetrafluoroborate as an initiator. Random copolymers were obtained from both of these monomer pairs, but attempted copolymerization of 2-vinyl-1,3-dioxane with 3,3-bis(chloromethyl)oxetane under similar conditions resulted in the homopolymer of the latter monomer. There were three structural units of 2-vinyl-1,3-dioxane in these copolymers as in its homopolymer: the “ester” unit, which was formed by vinyl addition with hydride shift followed by ring-opening rearrangement, the “vinyl” unit produced by ring-opening reaction, and the unit with a pendant 1,3-dioxane ring formed by simple vinyl addition. The fractions of the ester and vinyl units to the total 2-vinyl-1,3-dioxane units in the copolymer of 2-vinyl-1,3-dioxane with styrene decreased with decreasing 2-vinyl-1,3-dioxane content. On the contrary, the fraction of the vinyl unit in the copolymer of 2-vinyl-1,3-dioxane with 1,3-dioxolane increased slightly with decreasing 2-vinyl-1,3-dioxane content, while that of the ester unit decreased. The reactivities of the propagating species are discussed on the basis of these results.     

Dithietanes. Synthesis of N-substituted 2-imino-1,3-dithietanes and 2-imino-1,3-dithietane hydrochloride

The reaction of diethylphosphoryl isothiocyanate with potassium hydrosulfide gave potassium diethoxyphosphinyldithiocarbamate ( 3a ). This salt, with methylene bromide, afforded 2-diethoxyphosphinylimino-1,3-dithietane ( 5a ) in high yield. In concentrated hydrochloric acid, 5a was hydrolyzed to 2-imino-1,3-dithietane which was isolated as a stable hydrochloride ( 7 ). The synthesis of some other N-Substituted 2-imino-1,3-dithietanes is also described.     

Synthesis and reaction of 2-imino-1,3-thiazetidines and 2-imino-1,3-dithietanes

2-Imino-1,3-thiazetidines and 2-imino-1,3-dithietanes were synthesized and their reactivities were studied. The former readily underwent ring-opening reaction with amines to yield guanidine derivatives. The reaction products were applied to the synthesis of heterocycles such as triazoles and triazines. The latter was converted to isothiocyanate by the reaction of m-chloroperbenzoic acid.     

New Approach to the Synthesis of 1,3-Chloroisothiocyanatoalkanes. Synthesis of Tetrahydro-1,3-thiazine-2-thiones and 2-Alkylamino-5,6-dihydro-1,3-thiazines

A method was developed to prepare 1,3-chloroisothiocyanatoalkanes by reducing 1,3-isothiocyanato ketones using sodium borohydride at pH ~7 and subsequent treatment of the resultant 1,3-isothiocyanato alcohols with thionyl chloride. The reaction of 1,3-chloroisothiocyanatoalkanes with sodium hydrosulfide or amines gives substituted tetrahydro-1,3-thiazine-2-thiones or 2-amino-5,6-dihydro-1,3-thiazines.     

Cationic polymerizations of substituted 2-methylene-1,3-dioxocyclic acetals, 2-methylene-1,3-dithiolane and copolymerization of 2-methylene-1,3-dithiolane with 4-(t-butyl)-2-methylene-1,3-dioxolane1

Carbon black-supported sulfuric acid or BF₃·Et₂O-initiated polymerizations of 2-methylene-4,4,5,5-tetramethyl-1,3-dioxolane (1), 2-methylene-4-phenyl-1,3-dioxolane (2), and 2-methylene-4-isopropyl-5,5-dimethyl-1,3-dioxane (3) were performed. 1,2-Vinyl addition homopolymers of 1–3 were produced using carbon black-supported H₂SO₄ initiation at temperatures from 0°C to 60°C whereas both ring-opened and 1,2-vinyl structural units were present in the polymers using BF₃·Et₂O as an initiator. Cationic polymerizations of 2-methylene-1,3-dithiolane (4) and copolymerization of 4 with 2-methylene-4-(t-butyl)-1,3-dioxolane (5) were initiated with either carbon black-sulfuric acid or BF₃·Et₂O. Insoluble 1,2-vinyl addition homopolymers of 4 were obtained upon initiation with the supported acid or BF₃·Et₂O. A soluble copolymer of 2-methylene-1,3-dithiolane (4) and 4-(t-butyl)-2-methylene-1,3-dioxolane (5) was obtained upon BF₃·Et₂O initiation. This copolymer is composed of three structural units: a ring-opened dithioester unit, a 1,2-vinyl-polymerized 1,3-dithiolane unit, and a 1,2-vinyl polymerized 4-(t-butyl)-1,3-dioxolane unit. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2823–2840, 1999     

Investigation on radical polymerization of 2-methylene-1,3-dioxolanes and 2-methylene-1,3-oxazolidines

The reaction of 2-methylene-1,3-dioxolanes and 2-methylene-1,3-oxazolidines with benzoyl peroxide (acceptor radical) and with N-ethylmaleimide (acceptor) was investigated. It was shown that benzoyl peroxide adds to monomers 1a and 1b , giving the corresponding linear diester amides 1a and 1b respectively. The oxazolidine 1c adds benzoyl peroxide, without ring opening, by addition to the exomethylene group. Together with N-ethylmaleimide the oxazolidines 1a or 1b produce deep-colored charge transfer complexes, resulting in high molecular poly-N-ethylmaleimides probably via a radical mechanism. The 1,3-dioxolanes 2a and 2b were radically polymerized to produce polyacetals by vinyl polymerization. 2c was polymerized to produce randomly containing acetal units and ester units. The mechanism of polymerization of 2e is complex, affording polymers of nonuniform character. 2-Methylene-4-phenyl-1,3-dioxolane polymerization leads to polyester as the main structure, and to a lesser degree polyacetal structures. The chemical structures of the polymers were confirmed by NMR spectra and elemental analysis. © 1996 John Wiley & Sons, Inc.     

1,3-Dimercaptopropyl-2-thiopyrimidines

Reaction of 2-phenyl-1,3-dithiane-5-isothiuronium bromide with halopyrimidines gives 5-pyrimidylthio-1,3-dithianes and 1,3-dimercaptopropyl-2-thiopyrimidines. Some derivatives have been isolated and characterized. The complexing ability of the 1,3-dimercapto-2-thiopyrimidines has been examined by the metallic indicator method.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 5, pp. 605–610, May, 1970.     

Preparation of N-phosphorylated 2-oxo-1,3-oxazolidines and 6-methyl-2-oxo-1,3-tetrahydrooxazine

Conclusions N-Phosphorylated 2-oxo-1,3-oxazolidines and 6-methyl-3-(diethoxyphosphinyl)-2-oxo-1,3-tetrahydro-oxazine were prepared by allowing N-(diethoxyphosphinyl)imidocarbonyl dichloride to react with ethylene glycol, 1,2-propylene glycol, and 1,3-butylene and 2,3-butylene glycols in the presence of triethylamine in a dioxane medium.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 396–399, February, 1970.     

On the preparation of 2-halo alkyl substituted 1,3-dioxolanes and 1,3-dioxanes

Several methods for the preparation of 2-perfluoromethyl-substituted 1,3-dioxolanes and 1,3-dioxanes were tried. The method of Nerdel for the preparation of 1,3-dioxolanes, making use of the condensation between carbonyl compounds and oxiranes, was found to be suitable for perhalogenated ketones and aldehydes, and may even be extended to oxetanes, affording 2-perhaloalkylated 1,3-dioxanes.The yield of the cyclic acetals drops with inreasing substitution.     

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).     

Reaction of 1,3-diphenylbarbituric and 1,3 -diphenyl-2-thiobarbituric acids with diazotized sulfanilamides

The reaction of 1,3-diphenylbarbituric and 1,3-diphenyl-2-thiobarbituric acids with diazotized sulfaniiimides gives 1,3-diphenylalloxan and 1,3-diphenyl-2-thioalloxan phenylhydrazones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1276–1279, September, 1971.     

Reaction of 1,3-Dibromo- and 1,3-Dichloroacetone with 2-Aminoazaheterocycles

The reactions of 1,3-dibromoacetone with 2-aminoazines and 2-aminoazoles has been carried out for the first time and the pure intermediate quaternary salts have been isolated. They undergo cyclization to the corresponding imidazoazines and imidazoazoles containing a bromomethyl group. Similar condensations were carried out with 1,3-dichloroacetone.     

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-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.     

Simple Method for the Preparation of 1,3-Dithiol-2-one and 1,3-Dithiol-2-thione

Abstract

The reaction of diisopropyl xanthogen and thio-diisopropyl xanthogen disulfide with alkynes furnished 1,3-dithiol-2-one and 1,3-dithiol-2-thione.     

2-Nitromethyl-2-trichloromethyl-1,3-benzodioxoles and 2-nitromethyl-2-trichloromethyl-1,3-benzoxazolines: Synthesis and structure

A reaction of 1-bromo-3,3,3-trichloro-1-nitropropene with pyrocatechol, o-aminophenol, and their substituted derivatives led to 2-nitromethyl-2-trichloromethyl-1,3-benzodioxoles and 2-nitromethyl-2-trichloromethyl-1,3-benzoxazolines. The structure of the compounds synthesized was established by IR, ¹H and ¹³C NMR spectroscopy with HMQC and HMBC ¹H—¹³C experiments, and X-ray diffraction analysis.     

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 .