1.3- Oxazolidine-4-carboxylic acid methyl ester

The Sonogashira coupling can be considered a special case of catalytic alkyne activation. Interestingly, it is also possible to conduct alkyne activation under oxidative conditions in the presence of Pd catalysts without oxidative dimerization. Here, Costa and coworkers [139] have developed a Pd-catalyzed sequential carboxylation-alkoxycarbonylation of acetylenic amines in the presence of oxygen to give mixtures of Z- and -configurcd 2-oxo-oxazolidin-5-ylidene]-acetic acid methyl ester 193 and 194 in good to excellent yields (Scheme 75). 

Synonyms Dichlozolinate Ethyl 3-(3,5-dichlorophenyl)-5-methyl-2,4-dioxo-1,3-oxazolidine-5-carboxylate Ethyl 3-(3,5-dichlorophenyl)-5-methyl-2,4-dioxo-5-oxazolidine carboxylate Ethyl (RS) 3-(3,5-dichlorophenyl)-5-methyl-2,4-dioxo-1,3-oxazolidine-5-carboxylate Oxazolidine-5-carboxylic acid, 3-(3,5-dichlorophenyl)-2,4-dioxo-5-methyl-, ethyl ester Empirical C13H11CI2NO5... 

Oxazolidine A. See Dimethyl oxazolidine Oxazolidine-5-carboxylic acid, 3-(3,5-dichlorophenyl)-2,4-dioxo-5-methyl-, ethyl ester. See Chlozolinate Oxazolidinone CAS 70-07-5... 

Recently, Dominguez de Maria and co-workers [45] have studied experimentally the influence of the organocatalyst on the outcome of the aldol reaction reaction between acetone and isobutyraldehyde. Qrganocatalysts able to form bicyclic oxazolidine intermediates (proUne and prolinol) led predominantly to aldol adducts, while organocatalysts unable to form these oxazolidines (pyrrolidine, O-methyl prolinol and proline tcrt-butyl ester) afforded preferently (>2.5 1) the condensation product. In summary, most of the experimental evidence points toward a distinct catalytic role of oxazoUdinone intermediates in proline-catalyzed reactions. It should be pointed out, however, that DPT studies of the proline-catalyzed self-aldol reaction of propanal, in which the enamine carboxylic acid and the oxazoUdinone pathways were compared, concluded that the Seebach model was inadequate for rationalizing... 

Use of acetyl chloride in dichloromethane in the presence of 2,4,6-collidine or some other bulky base allowed selective esterification at primary sites the 5-(9-acetate 11, for example, was obtained in 91% yield from the 3,5-diol 10. Bis(2-oxo-oxazolidin-3-yl)phosphinic chloride (BOP-Cl), a new reagent for condensing alcohols and acids, has been employed in the preparation of primary esters 12. Treatment of unprotected methyl a-D-glucopyranoside, 2-acetamido-2-deoxy-D-glucose, and maltose with triphenylphosphine, DEAD, and an equimolar amount of a carboxylic acid (e.g.benzoic, methacrylic or adamantoic acid) allowed regioselective 6-0-esterifrcation (0-6 for... 

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