Polymer-supported oxazolidinones

Enantiomerically pure oxazolines and oxazolidinones have found widespread application in organic synthesis as chiral auxiliaries. They have been mainly used for the synthesis of enantiomerically pure amino acids but also as chiral auxiliaries to produce non-racemic enolates as pioneered by Evans.The reaction types proceeding with high stereocontrol include enolate alkylation, enolate oxidation, enolate halogenation, enolate amination, enolate acylation, aldol reaction and Diels-Alder reactions. 

Following the same procedure, Burgess et al reported the synthesis of chiral primary alcohols. Enantiomeric excesses of the products cleaved by reduction with LiBH4 ranged from 71-90 %. 

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Scheme 61 Polymer-supported synthesis of antimicrobial oxazolidinones...

In medicinal chemistry nitriles are very useful because they can be transformed into biologically important structures such as tetrazoles, triazoles, oxazoles, thia-zoles, oxazolidinones. .. A variety of aryl nitriles has been prepared in excellent yields by Pd-catalyzed coupling of aryl halides with Zn(CN)2 using polymer-supported triphenylphosphine as the ligand and DMF as the solvent under micro-wave irradiation conditions (Scheme 10.34) [76], Products were obtained in high yields and excellent purity without the need for purification. 

Narasaka reported that TADDOL-TiCl2 was able to catalyze asymmetric DA reaction of cyclopentadiene with oxazolidinone derivatives of acrylates in the presence of 4A MS [148]. A remarkable solvent effect on the enantioselectivity was observed, and high enantioselectivity was attained using mesitylene as the solvent. Cycloadditions to oxazolidinone derivatives of acrylates were also efficiently catalyzed by dendritic or polymer-supported TADDOL-Ti catalysts [149]. From the structural determination of the 3-(( )-3-cinnamoyl)-l,3-oxazolidin-2-one adduct, it can be deduced that the transition state involves binding of the dienophile to the titanium catalyst via the N-acyl-oxazolidinone [19a] (Scheme 14.59). The diastereo-and enantioselectivity of this type of catalyst are thus probably owing to both electronic and steric effects from TADDOL ligand. 

Watile RA, Bagal DB, Deshmukh KM, Dhake KP, Bhanage BM (2011) Polymer supported diol functionalized ionic liquids an efficient, heterogeneous and recyclable catalyst for 5-aryl-2-oxazolidinones synthesis from CO2 and aziridines under mild and solvent free conditions. J Mol Catal A 351 196-203... 

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