Reaction of 2-isobutyl-5-methyl-4-phenyl-1,3,2-dioxaborinane with acetonitrile

Reaction of 2-isobutyl-5-methyl-4-phenyl-1,3,2-dioxaborinane (a mixture ofcis- andtrans-isomers in a 81 : 19 ratio) with acetonitrile yielded 2,5-dimethyl-4-phenyl-5,6-dihydro1, 3-oxazine as a mixture ofcis- andtrans-forms in a 50 : 50 ratio. The possible mechanism of this transformation is discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1297–1298, May, 1996.     

Structure and reactions of benzo-4-diphenylphosphino-2-phenyl-1,3,2-dioxaborinane

The crystal structure of 5,6-benzo-4-diphenylphosphino-2-phenyl-1,3,2-dioxaborinane 1 indicates the occurrence of an interaction between the π-systems of the 1,3,2-dioxaborinane ring and the appropriate phenyl group of the diphenylphosphino group. Complexes of compound 1 with PtCl₂, PdCl₂, and Cul were synthesized. Compound 1 and its complexes are readily hydrolyzed in solution to give diphenylphosphine and its corresponding complexes (NMR).     

Reactions of 2-(5-methyl-2-phenyl-2H-1,2,3-diazaphosphol-4-yl)- 4H-1,3,2-benzodioxaphosphinin-4-one with chloral and hexafluoroacetone

Reaction of 2-(5-methyl-2-phenyl-2H-1,2,3-diazaphosphol-4-yl)-4H-1,3,2-benzodioxaphosphinin-4-one with chloral occurs at Piii atom of the 1,3,2-dioxaphosphinine cycle giving mostly 2-chlorocarbonylphenyl 2,2-dichlorovinyl (5-methyl-2-phenyl-2H-1,2,3-diazaphosphol-4-yl)phosphonate, whereas hexafluoroacetone incorporates into the 1,3,2-dioxaphosphorine cycle affording the corresponding 1,3,2-benzodioxaphosphepine.     

Conformational studies of 2-anilino-substituted 1,3,2-oxazaphospholanes

A series of 2-anilino-2-thio-1,3,2-oxazaphospholanes derived from ephedrine has been synthesized and conformationally studied by proton NMR and X-ray crystallography. The NMR data can be interpreted in terms of twist-envelope conformations in which the anilino substituents on phosphorus adopt predominantly equatorial positions. X-ray crystal structures of (2R,4S,5S)-2-anilino-2-thio-3,4-dimethyl-5-phenyl-1,3-2-oxazaphospholane, (2R,4S,5S)-2-(4-fluoroanilino)-2-thio-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholane, and (2R,4S,5S)-2-(4-methoxyanilino)-2-thio-3,4-dimethyl-5-phenyl-1,3,2-oxazaphosholane have been carried out, and these compounds adopt envelop, twist-envelope, and twist-envelope conformations, respectively, with the anilino moieties equatorial.     

Configuration and isomerization of 2,4,5-substituted 1,3,2-dioxaborinanes

Reaction of esters of isobutylboronic acid with 2-methyl-1-phenyl-1,3 propanediol and 2-benzyl-1,3-butanediol gave 2-isobutyl-5-methyl-4-phenyl- and 4-methyl-5-benzyl-1, 3, 2-dioxaborinanes respectively, with a preponderance of the cis-isomers in the mixtures. Cis-2-isobutyl-5-methyl-4-phenyl-1, 3, 2-dioxaborinane was converted to thetrans isomer on heating to 150°C with a catalytic amount of ZnCl₂.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1291–1294, September, 1995.     

Quantum-chemical investigation of conformational characteristics of the complex of 2-methyl-1,3,2-dioxaborinane with dimethyl ether

With the help of the quantum-chemical approximation MP2/6-31G(d)//HF/6-31G(d) conformational characteristics were investigated of donor-acceptor associate of 2-methyl-1,3,2-dioxaborinane with dimethyl ether, 1:1. The character of the conformational isomerization of the adduct differs from that established for the proper cyclic boric ester and involves an interconversion between two conformers nondegenerate by the energy. The stability of the associate under study is comparable with those of the molecular complexes of 2-methyl-1,3,2-dioxaborinane with water and methanol.     

Analysis of the Conformational Composition of 2-Alkyl-4-phenyl-1,3,2-oxazaborinanes

The empirical MM2 and semiempirical AM1 methods were used to calculate the energy of model 2-methyl-4-phenyl-1,3,2-oxazaborinane with full optimization of the molecular geometry. Comparison of the experimental coupling constants for the 2-isobutyl analog and calculated coupling constants as well as the data for the relative energy of the individual conformers indicated that these compounds form a multicomponent equilibrium system containing sofa and a family of half-chair forms.     

1,3-Heterazolidin-2-one as starting materials for optically active 1,3,2-oxazaborolines and 1,3,2-diazaboroline derived from ephedrines

(4R,5R)-3,4-Dimethyl-5-phenyl-1,3,2-oxazaboroline (1a) derived from pseudoephedrine and (4R,5S)-1,3,4-trimethyl-5-phenyl-1,3,2-diazaboroline (1d) derived from ephedrine have been prepared from the corresponding 1,3-heterazolin-2-one. Hydrolysis of 1d afforded the 1-methyl-3-(methylamine)-2-phenyl-propylamine 5. The structures were established from ¹H, ¹³C and ¹¹B NMR data. The X-ray diffraction analysis of (4R,5S)-(+)-3,4-dimethyl-5-phenyl-1-hydro-1,3-diazolidine-2-one (4e) was performed. Isomeric N-monoborane adducts of the 1,3,2-diazaboroline 1d were prepared, and their structures were deduced from the NMR data.     

Mass spectra of a series of 2-p-substituted phenyl-1,3,2-dioxaborolanes

The mass spectra of a series of 2-p-substituted phenyl-1,3,2-dioxaborolanes have been examined and compared with the mass spectrum of 2-phenyl-1,3,2-dioxaborolane. Formation of the substituted ion [C₇H₆X]⁺ by electron impact induced rearrangement has been found to be influenced significantly by the presence and nature of the substituent at the para position of the phenyl ring.     

Conformational analysis of the complex of 2-methyl-1,3,2-dioxaborinane with hydroxyl anion

Studies of the conformationsl transformations of the complex of 2-methyl-1,3,2-dioxaborinane with the hydroxyl anion performed by the quantum-chemical method HF/6-31+G(d) showed that they are more versatile than those in the initial boric ester, include the existence of six minima, five transition states, and are close to the conformational behavior of 1,3-dioxanes.     

Synthesis and Some Properties of 2-(5-Methyl-2-Phenyl-2H-1,2,3-Diazaphosphol-4-yl)-4H-Benzo[d]-1,3,2-Dioxaphosphorin-4-One

Abstract

2-(5-Methyl-2-phenyl-2Н-1,2,3-diazaphosphol-4-yl)-4H-benzo[d]-1,3,2-dioxaphosphorin-4-one 1 readily reacts with hexafluoroacetone, mesoxalic acid diethyl ester, trifluoropyruvic acid ethyl ester and chloral to give 2-(5-methyl-2-phenyl-2H-1,2,3-dizaphosphole-4-yl)-derivatives of 1,3,2- and 1,4,2-dioxaphosphepines.     

The interaction of 2-(5-methyl-2-phenyl-2h-1,2,3-diazaphosphol-4-yl)-4h-benzo[e]-1,3,2-dioxaphosphinin-4-one with activated carbonyl compounds. Synthesis of bis-heterocyclic systems containing di- and tetracoordinated phosphorus

The interaction of 2-(5-methyl-2-phenyl-2H-1,2,3-diazaphosphol-4-yl)-4H-benzo[e]-1,3,2-dioxaphosphinin-4-one with mesoxalic and trifluoropyruvic acids ethyl and diethyl esters, hexafluoroacetone and chloral proceeds with an exclusive participation of P(III) atom and allows to obtain 2-(5-methyl-2-phenyl-2H-1,2,3-diazaphosphol-4-yl)-derivatives of 1,4,2- and 1,3,2-dioxaphosphepines as well as dichlorovinylphosphonate, being the product of Perkow reaction in the case of chloral.     

Reactions of 1,3,2-dioxaphospholane derivatives with thiocyanatoalcohols

The reactions of 2-dimethylamino-, 2-methoxy-, 2-chloro-4,5-dimethyl-1,3,2-dioxaphos-pholanes with 4-thiocyanato-2-butanol in all cases yield 2-(1-methyl-3-thiocyanatopropoxy)-4,5-dimethyl-1,3,2-dioxaphospholane. The latter reacts with elemental sulfur to form the corresponding thiophosphate.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2130–2131, December, 1993.     

Molecular structure and conformational preference of 2-methyl-5-nitro-5-bromo-1,3,2-dioxaborinane and its complex with pyridine

The molecular structure of 2-methyl-5-nitro-5-bromo-1,3,2-dioxaborinane and its complex with pyridine is determined by single crystal X-ray diffraction. The structure of the synthesized compounds in the solution is also confirmed by the NMR spectroscopy data, and the conformational preference of their molecules is confirmed by the calculations using hybrid density functional theory.     

Determination of trace ethylene glycol in industrial solvents and lubricants using phenyl boronic acid derivatization and multidimensional gas chromatography

A practical gas chromatographic approach is introduced for the characterization of trace ethylene glycol in industrial solvents and lubricants. The analytical approach employs single step derivatization technique that effectively converts ethylene glycol to the cyclic boronate ester (2-phenyl-1,3,2-dioxaborolane), using phenyl boronic acid as a derivatizing reagent. The separation of the derivatized product was achieved by using multidimensional gas chromatography. Heavy lubricant matrices like engine crankcase oil were back-flushed to improve sample throughput and system cleanliness. Detection and quantitation of 2-phenyl-1,3,2-dioxaborolane was conducted with mass spectrometry in selected ion monitoring mode.     

PSEUDOROTATION IN MONOCYCLIC OXYPHOSPHORANES WHICH CONTAIN CHIRAL CENTERS

Abstract

Phenylbis[2-methyl-1-butoxy]phosphine has been allowed to react with butanedione to produce 2,2-bis[2-methyl-1-butoxy]-2-phenyl-4,5-dimethyl-1,3,2-dioxaphophol-4-ene. This material is a mixture of three diastereomers. It has been reported that 2,2-bis[tetrahydrofurfuyloxy]-2-phenyl-4,5-dimethyl-1,3,2-dioxaphosphol-4-ene is a mixture of only two diastereomers. The present work suggest that two of the diastereomers of the tetrahydrofurfuryloxy compound interconvert via hexacoordinated zwitterionic intermediates which involve addition of the oxygen of the tetrahydrofuran ring to phosphorus.     

Conformational analysis of 2-methyl-1,3,2-dioxaborinane in the presence of an ammonia molecule

Nonempirical quantum chemical methods RHF//STO-3G, 3-21G and 6-31G(d) were used for the investigation of the conformational properties of molecular complexes of 2-methyl-1,3,2-dioxaborinane with ammonia (1:1). Two types of possible associates are revealed: with donor-acceptor N→B bond and with intermolecular NH···O hydrogen bond. Their calculated relative stability and conformational behavior are determined not only by the spatial orientation of the donor and the acceptor but also by the concepts of the used calculation approach.     

Borylation of calix[4]resorcinols under ultrasonic irradiation

The use of ultrasonic irradiation in the reactions of trialkyl borates with octahydroxytetraoctyl[l ₄] metacyclophane allowed us obtaining tetraalkoxyboratocavitands with higher yields and under milder conditions. We first obtained 1,3,2-dioxaborolane and 1,3,2-dioxaborinane derivatives of tetraoctyl[l ₄]metacyclophane using ultrasonic irradiation. Boratocavitands were converted into the corresponding amine complexes with isobutylamine.     

Conformational transformations and autooxidation of 5-bromo-2-(2-methylpropyl)-5-nitro-1,3,2-dioxaborinane

Conformational study of 5-bromo-2-(2-methylpropyl)-5-nitro-1,3,2-dioxaborinane at the DFT PBE/3ξ level of theory revealed the only sofa–sofa interconversion pathway through a transition state corresponding to 2,5-twist conformer. The barrier to internal rotation of the axial nitro group is several times higher than that for the equatorial nitro group. According to the ¹H, ¹³C, and ¹¹B NMR, IR, and X-ray diffraction data, the main autooxidation products of 5-bromo-2-(2-methylpropyl)-5-nitro-1,3,2-dioxaborinane are 2-bromo-2-nitropropane-1,3-diol and boric acid.     

Quantum-chemical study on conformations of molecular complexes formed by 2-methyl-1,3,2-dioxaborinane with methylamine

Conformations of 1: 1 molecular complexes of 2-methyl-1,3,2-dioxaborinane with methylamine were studied in terms of restricted Hartree-Fock approximation using STO-3G, 3-21G, and 6-31G(d) bass sets. The results showed possible formation of two types of complexes, one with dative N→B bond, and the other with intermolecular hydrogen bond NH … O. Their relative stability and conformations are determined by both mutual orientation of the components and basis set used.