Oxazolidones hydroxy— from

A mixture of 24.1 g (0.10 mol) of 3-o-methoxyphenoxy-2-hydroxy-1 -propyl carbamate and 6.0 g (0.10 mol) of urea was heated rapidly to the temperature range of 180°C to 200°C, and maintained there for five hours. The reaction melt was poured into 50% ethyl alcohol, from which the product crystallized as a white solid. The crude yield was 18.3 g (82%) melting point 131.5°C to 137 t. Crystallization from water and 95% alcohol gave 9.0 g (40.3%) of pure 5-o-methoxyphenoxymethyl-2-oxazolidone melting point 141°Cto 143. This melting point was not depressed when the material was mixed with an authentic sample. In additional runs acetone was used Instead of ethyl alcohol with equivalent results. 

Telomers 422 (n = 2) and other 4-halogeno-l,3-dioxolan-2-ones were shown288 to react readily with ammonia or primary aliphatic amines, with formation of 4-hydroxy-2-oxazolidones (460). The latter, for which the trans arrangement of the hydrogen atoms of the oxazoli-done ring was deduced from H-n.m.r. data, readily underwent replacement of the hydroxyl group by a phenyl group on reaction with... 

Scheme 189 Preparation of new UV

Evans et al. utilized the chiral oxazolidones to prepare optically pure 3-hydroxy-a-amino acids, - important constituents of peptides and 3-lactams. As shown in Scheme 31, an asymmetric aldol reaction using the boron enolate derived from the V-(a-haloacyl)oxazolidone (68) provides the jyn-3-hydroxy-ot-halocarbonyl derivative (69), which is converted to the ann-3-hydroxy-a-azidocarbonyl derivative (70)... 

Syntheses of isocyanates from carboxylic acids/ and by the thermolysis of N-substituted 4-hydroxy-2-oxazolidones have recently appeared. In the latter method, the oxazolidones are prepared from amines and the overall reaction thus represents a conversion of amines to isocyanates without the use of phosgene. 

---