P chiral

Synthesis of a-Chiral and Homologated Aldehydes, Acids, and P-Chiral Alcohols. 

The conversion of chiral boronic esters iato optically pure B-aIkyl-9-BBN derivatives followed by reaction with a-bromoketones, a-bromoesters, or a-bromonitriles leads to the homologated P-chiral ketones, esters, and nitriles, respectively (526). 

Aversa M. C., Barattucci A., Bonaccorsi P. and Giannetto P. Chiral Sulfinile-1,3-dienes-Synthesis and Use in Asymmetric Reactions Tetrahedron Asymmetry 1997 9 1339-1367... 

Mikolajczyk, M. Drabowicz, J. Kielbasihski, P. Chiral Sulfur Reagents, CRC Press, Boca Raton, 1997. 

Guga P, Okruszek A, Stec WJ (2002) Recent Advances in Stereocontrolled Synthesis of P-Chiral Analogues of Biophosphates. 220 169-200... 

The rearrangement has also been extended to P-chiral S-phenyl phos-phinothiolate 79 and 0-phenyl phosphinothioate 80 (Scheme 21). With these asymmetric compounds, the C-P bond formation was found to occur stereose-lectively and with retention of configuration at phosphorus [51]. 

P-chiral dibenzophosphole oxide (52a) (Scheme 14) shows liquid crystalline behaviour [52], a property that is of interest in the area of electro-optical displays [53]. Chiral resolution of (52a) was achieved by column chromatographic separation of the diastereoisomers obtained following coordination of the o -benzophosphole (52b) to chiral cyclometallated palladium(II) complexes [52]. Notably, the presence of a stereogenic P-centre is sufficient to generate a chiral cholesteric phase. 

Recent Advances in StereocontroUed Synthesis of P-Chiral Analogues of Biophosphates... 

Guga P, Okruszek A, Stec WJ (2002) Recent Advances in StereocontroUed Synthesis of P-Chiral Analogues of Biophosphates. 220 169 -200 Hackmann-Schhchter N,see Krause W (2000) 210 261 -308 Hadjiaraoglou LP,see de Meijere A (2000) 207 149-227... 

Resolution of various racemic P-chiral phosphorylacetates 70 involved the same approach as was shown for sulfinylcarboxylates (Scheme 2). However, unlike the case of sulfinyl compounds, only PEE proved efficient for their P(0) analogues. 

The first P-chiral hydroxy phosphoryl compounds that were enzymatically resolved into enantiomers were o-hydroxyaryl phosphines and their oxides 75. The resolution was achieved via enzyme-assisted hydrolysis of their O-acetyl derivatives 74, the most effective enzymes being CE and Upase from C. rugosa (CRL) (Equation 35). The highest enanfioselectivity was observed in the case of naphthyl derivatives (Equation 36), having a P=0 moiety. ... 

Vespalec, R. and Bocek, P., Chiral separations by capillary electrophoresis present state of the art, Electrophoresis, 15, 755, 1994. 

Similar additions also occurred on vinylphosphine oxides. When the optically active vinylphosphine oxide was used, P-chiral alkylphosphine oxide was obtained with retention of the configuration (Eq. 10.27)60... 

The reaction of A-Boc protected amino acids alanine (184) and valine (185) with phenyldichlorophosphine in the presence of NEt3 was reported to lead to the clean formation of essentially one compound in each case, the P-chiral, tricoordi-nated, 1,3,2-oxazaphospholidinones 186 and 187 respectively (Scheme 52) [83],... 

The chiral l,3,5-triazepane-2,6-dione 149 and its ring fused analogue 150 have been shown to form H-bonded helical molecular tapes with P chirality on self assembly in the solid state. With 149, this self assembly proceeds through aromatic-aromatic ring interactions resulting in hollow tubular structures <06CC4069>. 

A few examples will illustrate the case. The parent trans-diene derivatives 31a and 3235 have nearly planar chromophores, but the Cotton effects are quite strong and opposite in sign (+15 and —27.9, respectively). This can be attributed mainly to the allylic axial C—CH3 bonds, which provide a positive contribution for compounds 31 and a negative for 32. Furthermore, the As values of P-chiral s-trans-31 are strongly dependent on the polarizability of the allylic C—X bond. 

Two reports have been made of the preparation of P-chiral phosphine oxides through reaction of chiral f-butylphenylphosphine oxide treated with LDA and electrophiles. The electrophiles included aldehydes,355 ketones,355 and benzylic-type halides.356 Optically active a-hydroxyphosphonate products have also been generated from aldehydes and dialkyl phosphites using an asymmetric induction approach with LiAl-BINOL.357... 

Haynes, R.K., Lam, W.W.-L., and Yeung, L.-L., Stereoselective preparation of functionalized tertiary P-chiral phosphine oxides by nucleophilic addition of lithiated tert-butylphenylphosphine oxide to carbonyl compounds, Tetrahedron Lett., 37, 4729, 1996. 

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