Steric structure of phosphorus-containing heterocycles - Communication 4. Axial arrangement of the alkoxy group in 1,3, 2-dioxaphosphorinanes according to the data of the method of dipole moments

1. The dipole moment of 2-alkoxy- and 2-phenoxy-l, 3,2-dioxaphosphorinanes and their spiro analogs with a tricoordinated phosphorus atom were determined. 2. A graphical method was proposed for the analysis of the data of the method of dipole moments of cyclic compounds. 3. In all the compounds studied, a chair conformation with axial (or diaxial for the spiro compound) arrangement of the alkoxy group with a gauche-orientation of the methoxyl and ethoxyl radicals and a cisorientation of the phenoxy group is realized. © 1974 Consultants Bureau

Formation of isomeric diphenyl pentaerythrityl diphosphites in transesterification of triphenyl phosphite with pentaerythritol

Employing the method of thin-layer chromatography, it was shown that the transesterification of triphenyl phosphite with pentaerythritol gives a mixture of two isomeric diphenyl pentaerythrityl diphosphites, the structure of which was confirmed by synthesis. © 1973 Consultants Bureau

The steric structure of phosphorus-containing heterocycles - Communication 9. Dipole moments of 2-diethylamino-1,3,2-dioxaphosphorinanes

1. The dipole moments of 2-diethylamino-1,3,2-dioxaphosphorinane, 3,9-bis-(N-diethylamino)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane, stereoisomeric 2-diethylamino-4-methyl-1,3,2-dioxaphosphorinanes, and 2-diethylamino-5-nitro-5-methyl-1,3,2-dioxaphosphorinane were determined. 2. The dipole moments of the P-O and P-N bonds in these compounds were determined by a graphical method, and the preferential equatorial orientation of the diethylamino group was established. © 1975 Plenum Publishing Corporation

Steric structure of phosphorus-containing heterocycles - Comunication 11. Aryl pyrocatechinphosphites

1. Para-substituted phenyl pyrocatechinphosphites were synthesized and their dipole moments and Kerr constants were determined. 2. A nonplanar structure of the benzodioxaphospholene ring with a dihedral bend angle of 155° and an axial phenoxyl substituent, gauche-oriented relative to the unshared pair of the phosphorus atom, was established from the joint examination of dipole moment data for the three p-X-aryl pyrocatechinphosphites. 3. Using the Kerr effect a change in orientation of the benzene ring was established upon going from pyrocatechin phenylphosphite to the o,o,p-tritert-butylphenyl derivative. © 1976 Plenum Publishing Corporation

Geometrical structures of phosphorus-containing heterocyclic compounds - 17. 2-Chloro-1,3,2-dioxaphospholanes with a four-coordinated phosphorus atom

1. Dipole moments and Kerr constants have been determined for 2-chloro-2-oxo- and 2-chloro-2-thiono-1,3,2-dioxaphospholanes and their methyl analogs. 2. Comparison of experimental and calculated values has shown that the preferred ring form in these compounds is envelope conformation with the carbon atom projecting out from the plane of the four remaining ring atoms. 4,4,5,5-Tetramethyl-3,2-dioxaphospholane exists in half-chair conformation. © 1978 Plenum Publishing Corporation

Structure and conformations of stereoisomeric 1,5;2,3-bis-O-(N-diethylamidothionephosphatq)-β-D-ribofuranosides from1H,31P, and13C NMR spectral data

1. The preferred conformations of the ribofuranose and 1,3,5,2-trioxaphosphepane rings in stereoisomeric 1,5;2,3-bis-O-(N-diethylamidothionephosphato)-β-D-ribofuranosides are the twisted envelope1TO and the chair C5 CO 1 C 1 conformations, respectively. 2. The conformations of the dioxaphospholane ring in the indicated compounds correspond to the twisted envelope P2 TO 2 and O3TP 2 conformations, distinguished by the cis or trans orientations of the O2P2O3 fragment relative to the H2 and H3 atoms of the ribofuranose ring. © 1981 Plenum Publishing Corporation

Stereochemistry of organophosphorus compounds Communication 9. Study of the NMR-1H and32P method of the configuration and conformation of cyclic phosphites based on dimethyl esters of D- and mesotartaric acids

1. Trans- and cis-orientations of the carbomethoxyl substituents at the C4 and C5 atoms in 1,3,2-dioxaphospholanes, synthesized on the basis of esters of D- and mesotartaric acids, respectively, were confirmed. 2. Conformation lability of the five-membered heterocycle of the compounds studied was demonstrated in the interval from -80 to 28°; on the basis of the vicinal spin-spin interaction constants3JPOCH and3JHCCH and their temperature dependence, conclusions were drawn on the most probable conformations, among which the pseudoconversion chiefly occurs. 3. On the basis of the heteronuclear Overhauser effect1H-{31P} and the paramagnetic shifts induced by Eu(DPM)3 and the aromatic solvent, information was obtained in support of a pseudoaxial arrangement of the substituents at the phosphorus atom. © 1976 Plenum Publishing Corporation

Stereochemistry of organophosphorus compounds Communication 9. Study of the NMR-1H and32P method of the configuration and conformation of cyclic phosphites based on dimethyl esters of D- and mesotartaric acids

1. Trans- and cis-orientations of the carbomethoxyl substituents at the C4 and C5 atoms in 1,3,2-dioxaphospholanes, synthesized on the basis of esters of D- and mesotartaric acids, respectively, were confirmed. 2. Conformation lability of the five-membered heterocycle of the compounds studied was demonstrated in the interval from -80 to 28°; on the basis of the vicinal spin-spin interaction constants3JPOCH and3JHCCH and their temperature dependence, conclusions were drawn on the most probable conformations, among which the pseudoconversion chiefly occurs. 3. On the basis of the heteronuclear Overhauser effect1H-{31P} and the paramagnetic shifts induced by Eu(DPM)3 and the aromatic solvent, information was obtained in support of a pseudoaxial arrangement of the substituents at the phosphorus atom. © 1976 Plenum Publishing Corporation

Structure and conformations of stereoisomeric 1,5;2,3-bis-O-(N-diethylamidothionephosphatq)-β-D-ribofuranosides from1H,31P, and13C NMR spectral data

1. The preferred conformations of the ribofuranose and 1,3,5,2-trioxaphosphepane rings in stereoisomeric 1,5;2,3-bis-O-(N-diethylamidothionephosphato)-β-D-ribofuranosides are the twisted envelope1TO and the chair C5 CO 1 C 1 conformations, respectively. 2. The conformations of the dioxaphospholane ring in the indicated compounds correspond to the twisted envelope P2 TO 2 and O3TP 2 conformations, distinguished by the cis or trans orientations of the O2P2O3 fragment relative to the H2 and H3 atoms of the ribofuranose ring. © 1981 Plenum Publishing Corporation

The geometric structures of phosphorus-containing heterocycles - Communication 10. A conformational analysis of 2-phenyl-1,3,2-dioxaphosphorinanes

1. Bond polarity parameters have been determined for the phosphorus in 2-phenyl-5,5-dimethyl-1,3,2-dioxaphosphorinanes and their phosphoryl and thiophosphoryl derivatives. 2. It has been established that the chair conformation with axial arrangement of the phenyl group is the preferred conformation in the 2-phenyl-5,5-dimethyl-1,3,2-dioxaphosphorinanes. The phosphoryl and thiophosphoryl analogs of the phosphorinanes exist as equilibrium mixtures of two chair forms, with the point of equilibrium shifted toward the conformer with equatorial arrangement of the phenyl group. © 1980 Plenum Publishing Corporation