Pyridyl Alcohols Research Articles

Pyridyl Phosphinites and Pyridyl Phosphites from Chiral Pyridyl Alcohols — A Modular Approach

AbstractChiral arylated pyridyl alcohols, pyridyl phosphinites and pyridyl phosphites were prepared by Suzuki arylation and/or O‐functionalization with a chlorodiarylphosphane or a chlorodiarylphosphite of chiral 2‐bromo‐6‐(1‐hydroxyalkyl)pyridines or 2‐(1‐hydroxyalkyl)pyridines, with the chirality originating from the chiral pool. The pyridyl alcohols were assessed as catalysts for the addition of diethylzinc to benzaldehyde and the P,N‐ligands were employed in the palladium‐catalysed substitutions of rac‐1,3‐diphenyl‐2‐propenyl acetate and rac‐2‐cyclohexenyl acetate with dimethyl malonate. Moderate enantioselectivities were observed in the catalytic reactions. We observed kinetic resolution of the racemic acetate when using one of the phosphite ligands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Readily Available New Pyridyl Alcohols Derived from D‐Glucose as Ligands for the Enantioselective Addition of Diethylzinc to Aldehydes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Readily available new pyridyl alcohols derived from d-glucose as ligands for the enantioselective addition of diethylzinc to aldehydes

A series of new chiral ligands derived from d-glucose has been synthesized and applied in the enantioselective addition of diethylzinc to aldehydes. Up to 94.1% e.e. was obtained in the ethylation reactions. In contrast to the ligands derived from d-fructose, ligands derived from d-glucose gave the opposite asymmetric induction.

Synthesis and Characterization of a Suite of Four Chiral Pyridyl Alcohols Derived from (‐)‐Menthol.

AbstractFor Abstract see ChemInform Abstract in Full Text.

1H NMR determination of absolute configuration of 1- or 2-aryl-substituted alcohols and amines by means of their diastereomers: novel separation technique of diastereomeric derivatives of pyridyl alcohols by extraction.

A convenient method to determine the absolute configuration of trans-2-aryl cyclohexanols, 1-aryl alcohols and amines was achieved. This method takes advantage of the 1H NMR spectroscopic observations of the remarkable high-field shift of C18-CH3 protons caused by the aromatic shielding effect. It is based on a discrimination of the difference of the environments in two diastereomers derived from 3 beta-acetoxy-5-etienic acid. Furthermore, it was observed that the corresponding diastereomeric derivatives of the pyridyl alcohols were simply separated by extraction based on the difference in their basicity.

Synthesis and characterisation of a suite of four chiral pyridyl alcohols derived from (−)-menthol

Reaction of menthylmagnesium chloride with pyridine-2-carbaldehyde gives a mixture of four isomeric chiral menthyl- and neomenthyl-substituted pyridylcarbinols which were fully characterised by a combination of spectroscopic and X-ray crystallographic methods. All of these alcohols catalyse the addition of diethylzinc to benzaldehyde, but with disappointing enantioselectivities.

Synthesis of new pryridyl alcohols and their use as catalysts in the asymmetric addition of diethylzinc to aldehydes.

Optically active new pyridyl alcohols 1-4, which can be easily synthesized by the reaction of (+)-camphor or (-)-menthone with lithiated pyridine derivatives, were applied as chiral ligands in the asymmetric addition of diethylzinc to aldehydes. Good yields with up to 94.0% enantiomeric excesses were observed in these reactions.

ChemInform Abstract: Studies on Olefin Epoxidation with t‐BuOOH Catalyzed by Dioxomolybdenum(VI) Complexes of a Novel Chiral Pyridyl Alcoholate Ligand.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Chiral bis(oxazoline) and pyridyl alcoholate dioxo-molybdenum(VI) complexes: synthesis, characterization and catalytic examinations

A group of chiral molybdenum(VI) complexes comprising MoO 2Cl 2L **, MoO 2Cl(THF)L * and MoO 2L 2 * [L **=chiral bis(oxazoline) and L *=chiral 2′-pyridyl alcoholate] have been prepared in good yields by reaction of the solvent substituted complex MoO 2Cl 2(THF) 2 with one or two equivalents of chiral ligand. Optically active aminoalcohols (L *) were obtained by reaction of the appropriate organolithium compound with (−)-menthone, (+)-8-phenylisomenthone, (−)-8-phenylmenthone, (+)-camphor and (−)-thujone. The molybdenum complexes were characterized by multinuclear NMR ( 1H, 13C, 17O, 95Mo) spectroscopy, IR spectroscopy and elemental analysis. 95Mo-NMR data reflected the donor capability of the organic ligands, whereas 1H-NMR and IR data were comparatively indifferent to the changes in the Lewis base ligand. The complexes were evaluated as catalysts for the asymmetric epoxidation of trans-β-methylstyrene by tert-butylhydroperoxide. The bis(oxazoline) complexes showed good catalytic activity but had low optical yields. Complexes of the type MoO 2Cl(THF)L * (L *=chiral 2′-pyridyl alcoholate) also exhibited high catalytic activity and enantiomeric excesses of up to 23%. The corresponding MoO 2L 2 * alcoholate complexes were considerably less active with comparable optical yields.

Studies on olefin epoxidation with t-BuOOH catalysed by dioxomolybdenum(VI) complexes of a novel chiral pyridyl alcoholate ligand

The chiral dioxomolybdenum(VI) complexes [MoCl{(1R,2S,5S)-8-trimethylsilyloxy-1-(2-pyridyl)mentholato}(O)2(THF)] and [Mo{(1R,2S,5S)-8-trimethylsilyloxy-1-(2-pyridyl)mentholato}2(O)2] have been prepared in good yields by reaction of the solvent substituted complex [MoCl2O2(THF)2] with one or two equivalents of chiral 2′-pyridyl alcohol. The optically active aminoalcohol was obtained by reaction of 2-pyridyllithium with (−)-(2S,5S)-8-trimethylsilyloxymenthone. The complexes are active catalysts in the homogeneous epoxidation of cyclic and linear olefins, dienes and terpenes by t-BuOOH. They present remarkable activity and excellent product selectivity in cyclooctene epoxidation (cyclooctene oxide was obtained in quantitative yield). In the case of limonene, regioselectivity is high in favour of the epoxidation of the internal cyclic double bond. Ring opening activity was also observed for α-pinene oxide, producing campholenic aldehyde and epoxy campholenic aldehyde.

Stereoselective synthesis of optically active pyridyl alcohols via asymmetric transfer hydrogenation of pyridyl ketones

A chiral Ru(II) complex, RuCl[( S,S)- N-( p-toluenesulfonyl)-1,2-diphenyl-ethylenediamine]( p-cymene), serves as an efficient catalyst for asymmetric transfer hydrogenation of 2-acetylpyridine with a substrate to catalyst molar ratio of 200–1000 with HCOOH as a hydrogen source to give ( S)-1-(2-pyridyl)ethanol in an almost quantitative yield and with 95% ee.

Synthesis of periphery-functionalized dendritic molecules using polylithiated dendrimers as starting material

A general method for the functionalization of Si-Cl terminated carbosilane dendritic molecules via organolithium or organomagnesium reagents is described. Quantitative exchange of the bromine atoms of 4-bromophenyl-functionalized dendrimers affords polylithiated species that are valuable starting materials for further functionalization, e.g., into pyridyl alcohols. The latter were successfully applied as catalyst precursors in a ruthenium-mediated ring-closure metathesis reaction.

Fructose derived pyridyl alcohol ligands: Synthesis and application in the asymmetric diethylzinc addition to aldehydes

AbstractEasily available chiral ketones were employed for the synthesis of optically active pyridyl alcohols, which were applied in the asymmetric diethylzinc addition to aldehydes, up to 89.4% e.e. was obtained using D‐fructose‐derived pyridyl alcohol.

ChemInform Abstract: Synthesis of Chiral Plane‐Extended Pyridyl Alcohols for the Enantioselective Addition of Diethylzinc to Aldehydes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis of chiral plane-extended pyridyl alcohols for the enantioselective addition of diethylzinc to aldehydes

Enantiomerically pure pyridyl alcohols, 1 and 2, were prepared from readily available racemic pyridyl alcohol 3 and applied to the enantioselective addition of diethylzinc to aldehydes resulting in moderately high enantiomeric excess (90%) in the case of benzaldehyde. In this study the first example of an alteration in the configuration of the product upon change of a non-chiral and non-coordinating part of the catalyst was observed.

First tungsten complexes with 2′-pyridyl alcoholate ligands: synthesis, structure, and application as novel epoxidation catalysts

First tungsten complexes with 2′-pyridyl alcoholate ligands: synthesis, structure, and application as novel epoxidation catalysts

ChemInform Abstract: Bioconversion of Optically Active Pyridyl Alcohols from the Corresponding Racemates with Plant Cell Cultures.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Bioconversion of Optically Active Pyridyl Alcohols from the Corresponding Racemates with Plant Cell Cultures.

A novel method for producing optically active pyridyl alcohols from the corresponding racemates was developed. When racemic pyridyl alcohol is incubated with Catharanthus roseus cell cultures, chiral alcohol is obtained in high yield with excellent enantiomeric excess (ee) (deracemization of racemate). Furthermore, the kinetic resolution of racemic pyridyl alcohol via oxidation gave the chiral compound with high ee.

ChemInform Abstract: Synthesis of Optically Active Pyridyl Alcohols from the Corresponding Racemates by Catharanthus roseus Cell Cultures.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The synthesis of optically active pyridyl alcohols from the corresponding racemates by Catharanthus roseus cell cultures

Abstract A novel method for producing optically active pyridyl alcohols 1a-f from the corresponding racemates was developed. When racemic 3-pyridylphenylmethanol 1b is reacted with Catharanthus roseus cell cultures, (−)-1b is obtained in 96% yield with 100 %ee.