Host-guest chemistry. The structure and proton disorder of the three-component crystal formed by 3(5)-methyl-4-nitropyrazole, (R, R)-(?)-trans-4,5-bis (hydroxydiphenylmethyl)-2,2-dimethyl-1,3-dioxolane and toluene

Toda, Fumio; Tanaka, Kōichi; Foces‐Foces, C.; Infantes, Lourdes; Claramunt, Rosa M.; López, Concepcíon; Elguero, José

doi:10.1002/(sici)1099-1395(199609)9:9<611::aid-poc821>3.0.co;2-m

Cited by 5 publications

(1 citation statement)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…31 P NMR (202 MHz, CDCl 3 ): δ 21.3 ppm. GCMS (EI, 70 eV) m/z = 223.05 (13), 222.05 (100), 190.10 (14), 189.10 (86), 171.10 165.05(10),(12), 143.15(12), 142.15 (96), 141.15(18), 140.05(50), 134.10 (22), 133.10 (50), 131.10 (20), 109.10 (11), 108.10 (28), 107.10 (69), 105.15 (24), 103.10 (18), 91.10 (10), 83.05 (12), 81.05 (11). Anal.…”

mentioning

confidence: 99%

Resolution of P-Sterogenic 1-Phenylphosphin-2-en-4-one 1-Oxide into Two Enantiomers by (R,R)-TADDOL and Conformational Diversity of the Phosphinenone Ring and TADDOL in the Crystal State

et al. 2021

View full text Add to dashboard Cite

The resolution of racemic 1-phenylphosphin-2-en-4-one 1-oxide (2), was achieved through the fractional crystallization of its diastereomeric complexes with (4R,5R)-(−)-2,2-dimethyl -α,α,α′,α′-tetraphenyl-dioxolan-4,5-dimethanol (R,R-TADDOL) followed by the liberation of the individual enantiomers of 2 by flash chromatography on silica gel columns. The resolution process furnished the two enantiomers of 2 of 99.1 and 99.9% e.e. at isolated yields of 62 and 59% (counted for the single enantiomer), respectively. The absolute configurations of the two enantiomers were established by means of X-ray crystallography of their diastereomerically pure complexes, i.e., (R)-2•R,R)-TADDOL and (S)-2•(R,R)-TADDOL. The structural analysis revealed that in the (R)-2•(R,R)-TADDOL complex, the P-phenyl substituent occupied a pseudoequatorial position, whereas in (S)-2•(R,R)-TADDOL, it appeared in both the pseudoequatorial and the pseudoaxial positions in four symmetrically independent molecules. Concurrent conformational changes of the TADDOL molecules were best described by the observed changes of a pseudo-torsional CO...OC angle that could be considered as a possible measure of TADDOL conformation in its receptor–ligand complexes. The structural analysis of the (R,R)-TADDOL molecule revealed that efficiency of this compound for use as an effective resolving factor comes from its ability to flexibly fit its structure to both enantiomers of a ligand molecule, producing a rare case of resolution for both pure enantiomers with one chiral separating agent. The resolved (R)-2 was used to assign the absolute configuration of a recently described (−)-1-phenylphosphin-2-en-4-one 1-sulfide by chemical correlation. In addition, an attempted stereoretentive reduction of (R)-2 by PhSiH3 at 60 °C revealed an unexpectedly low barrier for P-inversion in 1-phenylphosphin-2-en-4-one.

show abstract

mentioning

confidence: 99%

Resolution of P-Sterogenic 1-Phenylphosphin-2-en-4-one 1-Oxide into Two Enantiomers by (R,R)-TADDOL and Conformational Diversity of the Phosphinenone Ring and TADDOL in the Crystal State

et al. 2021

View full text Add to dashboard Cite

show abstract

The Unusual Properties of 5‐Methyl‐4,5,6,7‐Tetrahydro‐1H‐Indazole in the Solid State

Foces‐Foces

Hager

Jagerovic

et al. 1997

Chemistry A European J

View full text Add to dashboard Cite

Abstract:The crystal structure of the title compound was determined by X-ray analysis at 200K. Three independent molecules form a trimer joined by strong and linear N-H . . . N hydrogen bonds. There is another centrosymmetrically related trimer in the unit cell. Both tautomers (1H and 2 H ) are present in each trimer. Disorder of the NHprotons involved in the N-H . . N hydrogen bonds has been observed. Solid-state 13C CPMAS NMR was used to establish the dynamic nature of the NH-proton disorder, the title compound being the first example of proton transfer in a tautomeric mixture of pyrazoles with an equilibrium constant other than 1.

show abstract

Solid‐State NMR Study of the Tautomerism of Acetylacetone Included in a Host Matrix

Claramunt

López

Lott

et al. 2005

Helvetica Chimica Acta

View full text Add to dashboard Cite

The tautomerism of the enol form of acetylacetone (=pentane‐2,4‐dione; 1) inside a host cavity has been studied by means of solid‐state 13C‐NMR spectroscopy (SSNMR) using the variable‐temperature CPMAS technique. It appears that the enol form, 4‐hydroxypent‐3‐en‐2‐one (1a), exists in an equilibrium with an identical tautomer (1c) trough OH ⋅⋅⋅O proton transfer. The experimental results (energy barrier and chemical shifts) were rationalized by means of MP2 and GIAO calculations.

show abstract

Host-guest chemistry. The structure and proton disorder of the three-component crystal formed by 3(5)-methyl-4-nitropyrazole, (R, R)-(?)-trans-4,5-bis (hydroxydiphenylmethyl)-2,2-dimethyl-1,3-dioxolane and toluene

Cited by 5 publications

References 14 publications

Resolution of P-Sterogenic 1-Phenylphosphin-2-en-4-one 1-Oxide into Two Enantiomers by (R,R)-TADDOL and Conformational Diversity of the Phosphinenone Ring and TADDOL in the Crystal State

Resolution of P-Sterogenic 1-Phenylphosphin-2-en-4-one 1-Oxide into Two Enantiomers by (R,R)-TADDOL and Conformational Diversity of the Phosphinenone Ring and TADDOL in the Crystal State

The Unusual Properties of 5‐Methyl‐4,5,6,7‐Tetrahydro‐1H‐Indazole in the Solid State

Solid‐State NMR Study of the Tautomerism of Acetylacetone Included in a Host Matrix

Contact Info

Product

Resources

About