P-Stereoselectivity

Espelt, L., Parella, T., Bujons, J., Solans, C., Joglar, J., Delgado, A. and, Clapes, P., Stereoselective aldol additions catalyzed hy dihydroxyacetone phosphate-dependent aldolases in emulsion systems preparation and structural characterization of linear and cyclic iminopolyols from aminoaldehydes. Chem. Eur. J., 2003, 9, 4887. 

Sapountzis, I. Dohle, W. Knochel, P. Stereoselective preparation of highly functionalized (Z)-3-magnesiated enoates by an I-Mg exchange reaction. Chem. Commun. 2001, 2068-2069. 

Boudier, A. Darcel, C. Flachsmann, F. Micouin, L. Oestreich, M. Knochel, P. Stereoselective preparation and reactions of configurationally defined dialkylzinc compounds. Chem. Eur.J. 2000, 6, 2748-2761. 

While high stereoselection has been achieved in radical reactions which occur in a-position146 to a center substituted with a chiral auxiliary, diastereofacial control in the addition of achiral radicals to the P carbon is, in general, difficult to achieve.147 In connection with this, Toru et al. reported extremely high P-stereoselection in the addition of tertiary, secondary, and even primary alkyl radicals to chiral a-sulfinyl cyclopentanones in 1993.148 The effectiveness of the diastereoselective addition of achiral radicals has been shown to depend on the size of the substituent at the sulfmyl sulfur. Bulky chiral arylsulfmyl groups show excellent diastereoselectivi-ties (> 98 < 2). 

Bernard A, Arosio D, Manzoni L, Micheli F, Pasqnarello A, Seneci P. Stereoselective synthesis of conformationally constrained cyclohexanediols a set of molecnlar scaffolds for the synthesis of glycomimetics. J. Org. Chem. 2001 66 6209-6216. Arosio D, Vrasidas I, Valentin P, Liskamp RM, Pieters RJ, Bemardi A. Synthesis and cholera toxin binding properties of mnltivalent GMl mimics. Org. Biomol. Chem. 2004 2 2113-2124. 

Legros, J., Meyer, F., Coliboeuf, M., Crousse, B., Bonnet-Delpon, D., Begue, J.-P. Stereoselective Barbier-Type Allylation Reaction of Trifluoromethyl Aldimines. J. Org. Chem. 2003, 68, 6444-6446. 

Cao, X.-P. Stereoselective synthesis of substituted all-trans 1,3,5,7-octatetraenes by a modified Ramberg-Backlund reaction. Tetrahedron 2002, 58, 1301-1307. 

The Mitsunobu procedure was reported to be efficient in the case of fluoroalkyl alcohols [42], Unlike nonfluorinated alcohols, the acidic fluoro-alcohols [43] are efficiently deprotonated by the PPh3-DEAD adduct. This facilitates the displacement of the oxyphosphonium leaving group by an alkoxide. With the use of this reaction, a range of ethers 9 were prepared from fluoro-alcohols in good (from primary alcohols) to moderate yields (secondary alcohols) with high P-stereoselectivity (see Scheme 6.3 and Table 6.1). 

Dubois, N. Lapicque, R Magdalou, T Ablteboul, M. Netter, P. Stereoselective Binding of tire Glucuronide of Ketoprofen Enantiomers to Human Serum Albumin, Biochem. Pharmacol. 48, 1693-1699 (1994). 

McCarthy, J.R., Matthews, D.P, and Paolini, J.P, Stereoselective synthesis of 2,2-disubstituted 1-fluoroalkenes. ( )- [Fluoro(2-phenylcyclohexylidene)methyl]sulfonyl benzene and (Z)-[2-(fluoro-methylene)cyclohexyl]benzene, Org. Synth., 72, 216, 1993. 

Nicotra, F., Panza, L., Russo, G., Senaldi, A., Burlini, N., and Tortora, P., Stereoselective synthesis of the isosteric bisphosphono analogue of P-D-lfuctose-2,6-bisphosphate, J. Chem. Soc., Chem. Commun., 1396, 1990. 

Lavallee, J.-R, Spino. C.. Ruel. R.. Hogan. K.T., and Deslongchamps, P, Stereoselective synthesis of cw-decalins via Diels-Alder and double Michael addition of substituted Nazarov reagents. Can. J. Chem., 70, 1406. 1992. 

We speculated that the stereoselectivity in these reactions varied with the basicity of the anion moiety of the ionic liquids. The H-NMR spectra of C mim[OTf] and C mim[NTf2] in dilute acetone-imidazolium ring in the two compounds are shown in Fig. 3.3. The protons of C mim[OTf], which gave the higher P-stereoselectivity, appeared at a much lower field than those of C mim[NTf2]. 

We referred to Avent et al. s work [27] to interpret these spectra. We assumed that both of the ionic liquids were solvated to free ions in acetone, while the cation and the anion interacted somehow under solventless conditions, with the chemical shifts indicating the relative basicity of these anions. In fact, as can be seen in Table 3.2, the P"stereoselectivity of the glycosylation reactions with glucosyl fluoride was... 

Suedee, R. Srichana, T. Chotivatesin, R. Martin, G.P. Stereoselective release behaviors of imprinted bead matrices. Drug Dev. Ind. Pharm. 2002, 28 S), 545-554. 

Kristensen, K. Blemmer, T. Angelo, H.R. Christrup, L.L. Drenck, N.E. Rasmussen, S.N. Sjogren, P. Stereoselective pharmacokinetics of methadone in chronic pain patients. Ther. Drug Monit. 1996, 18, 111-221. 

Dickinson, R. White, I. Lieb, W.R. Franks, N.P. Stereoselective loss of righting reflex in rats by isoflurane. Anesthesiology 2000, 93, 837-843. 

Muller, N. Lapicque, F. Monot, C. Payan, E. Dropsy, R. Netter, P. Stereoselective binding of etodolae to human serum albumin. Chirality 1992, 4, 240-246. 

Bonnabry P, Desmeules J, Rudaz S, Leemann T, Veudiey J-L, Dayer P. Stereoselective interaction between piroxicam and acenocoumarol. BrJ Clin Pharmacol (1996) 41, 525-30. 

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