Oxazolidine-4,5-dione, methylation

Dichloro-4-nitroaniline -124 3-(3,5-Dichlorophenyl)-5-ethenyl-5-methyl-2,4-oxazolidine-dione-161,177... 

Irradiation of a benzene solution of 5-phenyl Af-benzoylformyl-A-p-tolylthiocar-bamate 48a (Scheme 23) gave 5-phenyl-5-phenylthio-3-p-tolyloxazolidine-2,4-dione 49a in 61% yield accompanied by oxazolidine-2,4-dione dimer (15%), p-tolyl isocyanate (22%), and diphenyl disulfide [29]. Photolysis of 48a in the solid state gave oxazolidine-2,4-dione 49a in 96% yield. For the N-methyl derivative, 48b, compared to the solution photochemistry in which only 8% of oxazolidinedi-one 49b was obtained with a complex mixture, radical cyclization proceeds selectively to give oxazolidinedione in 75% yield in the solid state. Whereas N-p-tolyl and A-methyl derivatives, 48a and 48b, formed achiral crystals, the N-benzyl derivative 48c crystallized in chiral space group P2. Photolysis of the chiral... 

The iV-substituted carbamoyl chloride is considered to be the intermediate of this reaction [626]. W-methyl-2-amino acids [1152] and N-benzyloxy-2-amino acids [22] react simiiarly to give the corresponding oxazolidine-2,5-diones. Phosgene has been used as a reagent for the enantiomeric resolution of iV-methyl-2-amino acids by gas chromatography [1152],... 

Figure 4. Conversion of methyl benzylpenicillinate to an oxazolidine-4,5-dione...

Vinclozoline (36), 3-(3,5-dichlorophenyl)-5-methyl-5-vinyI-1,3-oxazolidin 2,4-dione, is not toxic to mammals, fish or earthworms. 

Cyclization of dimethyl ( S)-malate (2) with methyl or ethyl isocyanate affords oxazolidin-2,4-diones (174) in 60 or 62% yield, respectively. This heterocyclic system provides the basic... 

This sequence has been used for the synthesis of 6-methoxymurrayanine (232) (Scheme 55) [214]. Reaction of butane-2,3-dione (226) with 4-methoxyphenyl isocyanate (227) to 4,5-dimethylene-3-(4-methoxyphenyl)-l,3-oxazolidin-2-one (228) followed by regioselective boron trifluoride-catalyzed Diels-Alder reaction with acrolein afforded the oxazolone 229. Only minor amounts of the undesired regioisomer were formed. Aromatization using 2,3-dichloro-5,6-dicyano-l,4-benzoquinone (DDQ) afforded the benzoxazol-2-one 230. Saponification of the cyclic carbamate and subsequent O-methylation led to the diarylamine 231. Finally, oxidative cyclization using stoichiometric amounts of palladium(ll) acetate provided 6-methoxymurrayanine (232). 

N-(3,4-Dichlorophenyl)-N -methyl-N -methoxyurea. See Linuron 3-(3,5-Dichlorophenyl)-5-methyl-5-vinyl-1,3-oxazolidine-2,4-dione 3-(3,5-Dichlorophenyl)-5-methyl-5-vinyl-2,4-oxazolidinedione. See Vinclozolin... 

Dichlorophenyl)-5-vinyl-5-methyl-1,3-oxazolidine-2,4-dione. See Vinclozolin... 

Amino-2-phenyl-propionic acid and 2-amino-2-ethylbutyric acid, 1172, react with benzyl chloroformate in aqueous alkali and then with thionyl chloride to give 4-methyl-4-phenyl-oxazolidin-2,5-dione [854] and 4,4-diethyl-oxazolidine-2,5-dione 1174 [855],... 

Treatment of 2-Cbz-amino-4-methyl-2-trifluoromethyl-pentanoic acid with SOCI2 at 80 °C gave 4-isobutyl-4-trifluoromethyl-oxazolidine-2,5-dione 1179 in 82% yield [857]. 

Similarly, 4-(4-benzyloxybenzyl)-4-methyl-oxazolidine-2,5-dione 1185 was formed by reacting the corresponding protected amino acid 1184 with PBrs in diethyl ether [860],... 

Acetylsulfanyl-4-methyl-oxazolidine-2,5-dione 1189 was prepared with PCI5 in diethyl ether [863]. 

D-Arabino-tetramethoxybutyl-l,3-oxazolidine-2,5-dione was obtained in 95% yield by treating 2-amino-2-deoxy-3,4,5,6-tetra-0-methyl-D-gluconic acid hydrochloride with diphosgene and active charcoal in THF at 55 °C [891]. 

A large-scale cyclization reaction of carbamates with functionalized butenoates, starting from carbamates prepared without phosgene, for the efEdent preparation of 3-(substituted phenyl)-5-isopropylidene-l,3-oxazolidine-2,4-dione derivatives (azaladones) having potent herbicidal adivity, has been described in a patent application [240]. By reacting an N-(substituted phenyl)carbamate 312 with a 2-hydroxy-3-alkenoic acid ester (for example, ethyl 2-hydroxy-3-methyl-3-butenoate) or a 3-alkoxy-2-hydroxyalkanoic add ester, at 210 °C for 15 h, azaladone 313 was formed in 71.5% yield. 

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