3-Acetyl-2-oxazolidone

Further support for this explanation is the fact that the chiral acetate enolates derived from A -acetyl-2-oxazolidone (46). in which the developing Rj <-> CH3 interaction leading to diastereomer A is absent, exhibit only poor diastereofacial selection. 

Acyl-l,3-oxazolidine-2-thiones, chiral (1). Nagao and co-workers1 have prepared the chiral 3-acetyl-l,3-oxazolidine-2-thiones (la and lb) and used them to effect diastereoselective aldol reactions. The two chiral auxiliaries show, as expected, opposite diastereoselectivities, but contrast with the diastereoselectivities observed with chiral 4-alkyl-2-oxazolidones (11, 379-381). This aldol reaction has been used to prepare the chiral azetidinone 4 (equation I) and (-I- )-Prelog-Djerassi lactone. 

A-Benzoylcycloprotobuxoline-C (180) displayed spectral properties which closely resembled those of the A-benzoylcycloprotobuxoline-D with the exception that the PMR spectrum of the former showed the presence of an A-dimethylamino group. Acetylation of A-benzoyl-cycloprotobuxoline-C led to an 0-acetate (188). Hydrolysis of 179 led to the debenzoylated compound 184 and benzoic acid. Similarly, hydrolysis of 180 furnished cycloprotobuxoline-C (185). It was postulated that the ease of hydrolysis of A-benzoylcycloprotobuxolines might be attributable to the effect of a neighboring hydroxy group. To verify this assumption 185 was treated with phosgene, whereupon the oxazolidone... 

The synthesis of (-)-A -acetyl-O-methylacosamine, " an amino sugar, is an interesting application of the process of cis-hydroxyamination catalyzed by palladium complexes of olefins developed by Trost and Sudhakar. Enantiomerically pure aldehyde 263 was first transformed to vinyl epoxide 264. The latter reacted smoothly with p-toluene sulfonyliso-cyanate in the presence of 1-3 mol% of palladium and 6-18 mol% of tiiisopropyl phosphite in THF at room temperature. As thermal reaction favored 0-aIkylation, these conditions led exclusively to A-p-toluenesulfonyl-2-oxazolidone 265 as shown in Scheme 60. 

A mixture of l,2,4,6-tetra-0-acetyl-3-carbobenzoxyamino-3-deoxy-j -D-gluco-pyranose and AlClg in chloroform shaken 40 min. at room temp. 2,4,6-tri-O - acetyl -1- - chloro -3- carbobenzoxyamino -1,3 - dideoxy - D - glucopyranose. Y 92.7%. F. e., also 2-oxazolidone ring formation (cf. Synth. Meth. 7, 361) s. Umezawa, S. Koto, and Y. Ito, Bull. Chem. Soc. Japan 36, 183 (1963). 

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