Jan Omelańczuk

Chiral t-butylphenylphosphinothioic acid: A useful chiral solvating agent for direct determination of enantiomeric purity of alcohols, thiols, amines, diols, aminoalcohols and related compounds

Abstract Enantiomers of t -butylphenylphosphinothioic acid were found to be useful chiral solvating agents (CSAs) for 1 H-NMR determination of enantiomeric excess (ee) of many classes of chiral organic compounds, such as alcohols, diols, thiols, mercaptoalcohols, amines, aminoalcohols, hydroxyacids and related compounds.

New procedures for the resolution of chiral tert-butylphenylphosphine oxide and some of its reactions

Abstract Racemic t -butylphenylphosphine oxide was resolved via formation of diastereoisomeric complexes with (+)-( R )-1,1′-binaphthalene-2,2′-diol and (+)-( S )-mandelic acid. With the latter complexing agent, separation of the essentially enantiopure (−)-( S )-enantiomer was achieved in a single complexation process. Addition of paraformaldehyde to this enantiomer gave α-hydroxymethyl- t -butylphenylphosphine oxide with high stereoselectivity and retention of configuration at phosphorus while its reaction with methyl bromoacetate in methanol/sodium methoxide resulted in the formation of methyl t -butylphenylphosphinate with inversion at phosphorus.

LIPASE-PROMOTED KINETIC RESOLUTION OF RACEMIC, P-CHIRAL HYDROXYMETHYLPHOSPHONATES AND PHOSPHINATES

Abstract Lipase-mediated acetylation of racemic P-chiral hydroxymethylphosphonates and phosphinates, and hydrolysis of their O -acetyl derivatives have been conducted under kinetic resolution conditions to give the enantiomerically enriched title products with up to 92% ee. Their absolute configuration has been determined by means of chemical correlation and CD measurements.

A general synthesis of optically active phosphines, phosphinites and thiophosphinites from alkylthio(alkylseleno)phosphonium salts and tris(dimethylamino)phosphine as a thiophilic agent

Abstract Tris(dimethylamino)phosphine was found to be a suitable thiophilic reagent which converts optically active alkylthio(alkylseleno)phosphonium salts into chiral tertiary phosphines and phosphinites with a high stereoselectivity. The first synthesis of optically active thiophosphinites from bis(alkylthio)phosphonium salts and tris(dimethylamino)phosphine is also reported.

Chiral 1,8-bis(tert-butylphenylphosphino)naphthalene oxides and sulfides: resolution and structures

Abstract Chiral racemic 1,8-bis( tert -butylphenylphosphino)naphthalene oxide ( 2a ) was resolved into enantiomers by fractional crystallization of its diastereomeric adducts 3a with (+)-(2 S ,3 S )-di- O -benzoyl tartaric acid (DBTA), followed by neutralization. Racemic 1,8-bis( tert -butylphenylphosphino)naphthalene ( 1a ) was oxidized with sulfur to two isomers of 1,8-bis( tert -butylphenyl-phosphino)naphthalene monosulfide, rac - 4a and rac - 4a ′, or 1,8-bis( tert -butylphenylphosphino)naphthalene disulfide, rac - 5a . The compounds were characterized by NMR spectroscopy ( 1 H, 31 P, 13 C). Crystal structures were determined by the X-ray method for (−)- 3a, rac - 4a , rac - 4a ′ and rac - 5a ; this allowed the determination of the absolute configuration ( S , S ) for the more soluble adduct (−)- 3a . It was found that rac - 1a undergoes partial epimerization in boiling xylene to give the meso form.

Optically active trivalent phosphorus compounds—I: Diastereoisomeric o-menthyl ethylphenylphosphinites: synthesis, chirality at phosphorus and stereochemistry of nucleophilic displacement reaction

Abstract The reaction between racemic ethylphenylchlorophosphine and menthol has been found to give a mixture of diastereoisomeric O-menthyl ethylphenylphosphinites (4) in unequal ratio. The diastereoisomeric content depends mainly on the tertiary amine used for the condensation. The chirality at phosphorus in the diastereoisomeric esters (4a and 4b) has been assigned by means of chemical correlation (conversion into optically active methylethylphenylphosphine oxide) and proton NMR spectra. It has been demonstrated that nucleophilic substitution at phosphorus in 4 occurs with inversion of configuration.

Configuration of the optically active phosphorus thioacids—I : Chemical correlation of the configuration of O-alkyl alkyl-phosphonothioic acids

Abstract Chirality of the P atom in O-alkyl methylphosphonothioic acids, Me(RO)P(S)OH (RMe, Et, Prn,Bun), O-alkyl ethylphosphonothioic acids Et( acids Pri(RO)P(S)OH (RMe,Et) was correlated with that of (+)R-O-isopropyl methylphosphonothioic acid, Me(PriO)P(S)OH. The chemical correlation was based on the synthesis of optically active O,O-dialkyl alkylphosphonothionates, R(RO)(R′O)P(S), from suitably substituted phosphonothioic acids via the corresponding O-alkyl alkylphosphonochloridothionates, R(RO)P(S)Cl. It has been shown that all the dextrorotatory O-alkyl alkylphosphonothioic acids have the R configuration. Additionally it has been demonstrated that alkaline hydrolysis occurs with inversion of configuration at the P atom connected with the isopropyl group.

Stereochemistry of nucleophilic substitution reaction at a thiophosphoryl centre—IV: Chemical proof of Walden inversion☆

Abstract Optically active pyrophosphonothionates (II, III and IV) have been obtained in the reaction between optically active O-ethyl ethylphosphonothioic acid (I) and 2-chloro-2-oxo-5,5-dimethyl-1,3,2-dioxaphosphorinan, diethyl phosphorochloridate and O,O-diethyl phosphorochloridothionate respectively. It has been found that alkaline hydrolysis of these anhydrides occurs with full inversion of configuration at the thiophosphoryl centre. The reaction is discussed from the point of view of stereochemistry and the reaction mechanism.

The first stereoselective synthesis of chiral halogenophosphines: optically active tert-butyl(phenyl)chlorophosphine

The reaction of optically active tert-butyl(phenyl)(methylthio)chlorophosphonium trifluoromethanesulfonate 1 with tris(N,N-dimethylamino)phosphine at low temperature was found to give, stereoselectively, optically active tert-butyl(phenyl)chlorophosphine; when the salt 1 was treated with triphenylphosphine optically active tert-butyl(phenyl)chlorophosphine and methyl tert-butyl(phenyl)phosphinothioite were obtained as the result of the respective desulfurization and dehalogenation processes.

Stereochemistry of the reaction between phosphoryl compounds and phosphorus pentasulphide (P4S10.)

Abstract Phosphorus pentasulphide converts optically active phosphonothiolates into the corresponding phosphonodithioates with predominant retention of configuration at the phosphorus atom. Reaction of the optically active methylpropylphenylphosphine oxide was found to afford racemic methylpropylphenylphosphine sulphide.