Chiral phosphorus derivatives

After the purification of the reaction mixture the cationic catenane 160 was obtained. After removal of the copper, the two diastereoisomers of the free catenane 160 were separated by preparative HPLC and fully characterized. 160 represents an unprecedented class of chiral phosphorus derivatives, that is, phos-phoms-containing chiral [2]catenanes, whose properties in coordination chemistry and catalysis should be investigated [145]. 

Chirality is an important part of today s chemistry and, in this respect, the pseudo-octahedral geometry of hexacoordinated phosphorus derivatives is interesting as it suffices to coordinate to the central atom three identical sym-... 

C-chiral hydroxy phosphorus derivatives, which have been described so far in the literature, are secondary alcohols. Thus, the syntheses of non-racemic compounds of this type comprise two main approaches (cf. C-chiral hydroxyalkyl sulfones. Section 2.2) asymmetric reduction of the corresponding keto derivatives and resolution of racemic hydroxyalkanephosphorus substrates. 

Earlier, the first chiral tetrathiophosphate derivative 311, in which one can recognize 1,3,2-dithiaphospholane subunits, was synthesized in good yield by reacting tetrabutylammonium camphoryl-D-sulfonate (310) with phosphorus pentasul-fide (Scheme 74) [111],... 

Hydrogenation of ct-dehydroamino acid derivatives has been a typical reaction to test the efficiency of new chiral phosphorus ligands. Indeed, a number of chiral phosphorus ligands with great structural diversity are found to be effective for the Rh-catalyzed hydrogenation of a-dehydroamino acid derivatives. Since (Z)-2-(acetamido)cinnamic... 

Amino ketones and their hydrochloride salts can be effectively hydrogenated with chiral rhodium catalysts (Table 33.5). The rhodium precatalysts, when combined with chiral phosphorus ligands such as BPPFOH 4 [20b], hydroxyproline derivatives ligands [20-24], Cy,Cy-oxo-ProNOP 15, Cp,Cp-oxoProNOP 16, and... 

There is a short account on the preparation of chiral LSRs5 although most chiral LSRs derived from (natural) (l/ )-camphor are commercially available. LSRs should be stored over phosphorus pentoxide. 

Chiral Phosphorus Compounds Koizumi et al. 251 have prepared a series of chiral organophosphorus compounds (256) in which the phosphorus atom is the asymmetric center, whereby amino acid derivatives were used as chiral auxiliary reagents. 

The modification of the CpFe(L)2+ fragment in 39 with chiral phosphorus donor ligands based on chiral 1,2-dioles was investigated by Kxindig and coworkers and tested in the reaction of acrolein derivatives (Scheme 9.28) [72-74],... 

Intermolecular aza-Wittig reaction has been described for the one-step synthesis of pyrazolofl, 5-a Ipyrimidinc and imidazo[l,2-fc]pyrazole derivatives.37 The asymmetric synthesis of ft-quaternary azacycles has been accomplished by aza-Wittig reaction mediated by chiral phosphorus(ni) reagents.38... 

Another important source of chiral auxiliaries for the synthesis of optically active phosphorus derivates are the C2 symmetric diamines such as 1,2-diaminocyclohex-anes. In 1994, Hanessian and co-workers described the use of A,/V -dimethyl-(R,R)-1,2-diaminocyclohexane 93 as a chiral auxiliary in the synthesis of optically pure or enantiomerically enriched a-alkyl a-amino phosphonic acids [49], Starting from easily accessible optically pure diamine 93, they synthesized in good yield (75 %) enantiomerically pure (R,R)-ethylphosphonamide 94 by condensation with ethyl phosphonic dichloride in benzene in the presence of triethylamine (Scheme 43). 

On the other hand, enantioselective conjugate addition to 2-cyclohexenone with lithium dibutylcuprates (having a noncova-lently bound chiral phosphorus ligand derived from ephedrine) affords 3-butylcyclohexanone with up to 76% ee (eq 14). ... 

The first highly diastereoselective hydrophosphonylation of heterocyclic imines, 3-thiazolines (330) by a chiral phosphorus reagent BINOL, has been performed. The relative configuration of BINOL and the newly formed stereogenic centre in the a-amino phosphonic acid derivatives (331) have been elucidated by X-ray analysis. 

Studies of the asymmetric synthesis of chiral phosphorus compounds, (100) via the destructive-selective oxidation of (99) with various camphor derived oxaziridines has been described (91CB1627). The des were mostly modest, for example 8-48%. 

P-heterocycles and phosphorus derivatives of heterocycles as new chiral ligands for enantioselective hydrogenation 03CRV3029. 

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