K. Michał Pietrusiewicz

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.

Chiral β-aminophosphine oxides as ligands for ruthenium assisted enantioselective transfer hydrogenation of ketones

Abstract Enantiopure β-aminophosphine oxide ligands have been synthesized and used in asymmetric transfer hydrogenation of ketones. Optically active alcohols are obtained in high yields and with up to 84% enantiomeric excess.

The synthesis of homochiral inositol phosphates from myo-inositol

Abstract A new synthetic procedure for efficient conversion of myo -inositol into homochiral inositol phosphates is presented, and is illustrated with total synthesis of myo -inositol 1-phosphate, 2-deoxy- myo -inositol 1-phosphate, myo -inositol 3-phosphate, myo -inositol 4-phosphate, myo -inositol 1,4-bisphosphate, myo -inositol 1,4,5-trisphosphate, and myo -inositol 3,4,5,6-tetrakisphosphate. The syntheses start with selfresolving myo -inositol camphanylidene cis -monoacetals 2a and 2a′ , which are obtained in one step from the parent cyclitol and D- and L-camphor dimethyl acetal, respectively, and are harvested conveniently by means of a precipitation driven equilibration. The syntheses feature in the key steps the selective monophosphorylation, selective bissilylation and selective trisacylation of 2a and 2a′ , as well as the use of dibenzyl phosphorochloridate and 2-dimethylamino-5,6-benzo-1,3,2-dioxaphosphepane for effecting mono and polyphosphorylations, respectively. In support of stereochemical assignments an X-ray structure of one of the intermediate fully protected inositol derivatives is also presented.

Optically active phosphine oxides. 3. Conjugate addition to vynil phosphine oxides in aqueous medium.

Abstract Optically active phosphine oxides are prepared in aqueous medium via Zn(Cu) promoted addition of alkyl halides to (−)-(S)-methyl-phenylvinylphosphine oxide.

Nitrone cycloadditions to 2,3-dihydro-1-phenyl-1H-phosphole 1-oxide. Double asymmetric induction and kinetic resolution by a chiral nitrone

Abstract The cycloadditions of nitrones with 2,3-dihydro-1-phenyl-1H-phosphole 1-oxide give a single cycloadduct deriving from a highly diastereoselective approach of the nitrone anti to the phenyl ring of phospholene oxide. When the chiral gliceraldehyde derived nitrone is used, only two diastereoisomers are produced in 1.7:1 ratio. The structural assignment based on NMR data and X-ray analysis of the major isomer established a trans C3–C4 stereochemistry (derived from endo TS with respect to nitrone) and a C3–C4′ relative stereochemistry of threo type in the major isomer and erythro in the minor one. Therefore, each enantiomer of phospholene oxide 6 gives exclusively one cycloadduct with five contiguous stereogenic centres in an established and predictable absolute configuration. The difference of reactivity of the two enantiomers allowed a partial kinetic resolution of the racemic phospholene oxide, affording (+)-(S) enantiomer with 90% enantiomeric excess.

Optically active phosphine oxides. 5. P-chiral 2-aminoethyl phosphine oxides☆

Abstract Homochiral 2-aminoethyl phosphine oxides are expeditiously prepared by thermal addition of primary and secondary amines to (−)-(S)-methylphenylvinylphosphine oxide. Their transformation into optically active 2-aminoethyl phosphines and 2-aminoethyl phosphine sulphides is exemplified.

The classical Kagan's amides are still practical NMR chiral shift reagents: determination of enantiomeric purity of P-chirogenic phospholene oxides

Abstract Application of the (S)-(+)-N-(3,5-dinitrobenzoyl)-1-phenylethylamine 1 and (S)-(+)-N-(3,5-dinitrobenzoyl)-1-(1-naphthyl)ethylamine 2 as chiral NMR shift agents for a variety of phospholene derivatives is described. 1H and 31P NMR spectra recorded in the presence of Kagans amides 1 or 2 show well resolved signals of vinylic protons as well as 31P signals and allow effective measurement of the enantiomeric excesses. The experimental rule for determination of the absolute configuration at P is also proposed.

The regioselectivity of nitrone cycloadditions to vinyl phosphorus compounds

Abstract The 13-dipolar cycloadditions of nitrones 1-5 to diphenylvinylphosphine oxide (6) sulfide (7) and selenide (8) were carried out. The cycloadditions of the nitrone 3 as a model to substituted vinylphosphorus derivatives 28-36 were also carried out with satisfactory results with the exception of the sulfoxide 33. Nuclear Magnetic Resonance spectroscopy (31p 1H and 13C) allowed the complete unambiguous identification and assignment of the regiochemistry to all the products as well as their relative quantitative determination. The relative stereochemistry of isoxazolidine stereocenters was also assigned to compounds 9-23 and 37-46 on the basis of 1H and 13C NMR data.

Optically active Phosphine oxides : Synthesis and absolute configuration of (menthoxycarbonylmethyl) phenylvinyl phosphine oxide

Abstract The enantiomeric(-)(menthoxycarbonlymethyl)phenylvinylphosphine oxide 1b has been prepared and its absolute configuration rigorously established via chemical correlation. One-step decarbalkoxylation of (-)-ethyl(methoxycarbonylmethyl)phenyphosphine oxide 6 was effected with LiCl-H 2 O-DMSO and shown to proceed without concomitant racemization at phosphorus.

Reduction of functionalized tertiary phosphine oxides with BH3.

A direct stereoselective conversion of tertiary hydroxyalkylphosphine oxides to the corresponding tertiary hydroxyalkylphosphine-boranes involving facile reduction of the P═O bond by BH3 under mild conditions has been developed. The unprecedented facility of reduction of the strong P═O bond by BH3, a mild reducing agent, has been achieved through an intramolecular P═O···B complexation directed by proximal α- or β-hydroxy groups present in the phosphine oxide structures. As established by two chemical correlations, the developed transformation of hydroxyalkylphosphine oxides into hydroxyalkylphosphine-boranes takes place with complete inversion of configuration at P.