5-Methyl-l,3-oxazolidine

General procedure. (4R)-N-Benzyloxycarbonyl-4-cyano-2,2-dimethyl- l,3-oxazolidine and (4R,5R)-N-Benz lox carbonyi-4-cyano-2,2-dimethyl-5-methyl-l,3-oxazolidine 1478 [1120] A solution of the amide 1477 (36 mmol), p-tosyl chloride (10.29 g, 54 mmol), and pyridine (70 mL) was purged with Ar and stirred at 80 °C for 1 h. The cmde mixture was then concentrated under reduced pressure and diluted with EtOAc (200 mL). The organic phase was washed with 2 n Hd (3 x 50 mL), water (3 x 50 mL), and saturated NaHCOs solution (3 x 50 mL), dried (Na2S04), concentrated, and purified by flash chromatography (dichloromethane/hexane, 1 1) yield 70-88% of 1478. 

Table 33 Minimum inhibition concentrations (MIC) of 3,3 -methylenebis (5-methyl-l,3-oxazolidine) (Source SCHUELKE MAYR)...

Richardson et al. [117] have applied gas chromatography with a chemiluminescence detection system to the determination of microgram levels of nitrosamines (N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosomorpholine and N-nitrosodiethanolamine, N-nitrosopyrrolid-ine, N-nitrosopiperidine and N-nitroso-5-methyl-l,3-oxazolidine) in potable water supplies. Nitrosamines may be removed from aqueous media by solvent extraction and subsequently concentrated by evaporation of the solvent, in order to detect levels as low as O.Olpg L... 

Benzaldehyde dimethylacetal (200 pi, 1.33 mmol) and a catalytic amount of p-toluenesulfonic acid (37 mg) are added to methyl (2R,3S)-3-(4-nitrobenzenesulfonamido)-3-phenyl-2-hydroxypropionate (315 mg, 0.83 mmol) in toluene 5 ml. The mixture is heated at 100°C under reduced pressure (15 mm mercury) with no condenser. After 1 h the crude reaction mixture is diluted with ethyl acetate and washed with water (2 times). After drying the organic layer over magnesium sulfate the crude material is purified by column chormatography (silica gel eluting with ethyl acetate/cyclohexane, 35/65) to give the (2S,4S,5R)-2,4-diphenyl-3-(4-nitrobenzenesulfonamido)-5-methoxycarbonyl-l,3-oxazolidine, melting point 118°-120°C. 

Chemical Name (/LS )-3-(3,5-dichlorophcnyl)-5-vinyl-l,3-oxazolidine-2,4-dione 3-(3,5-dichlorophenyl)-5-ethenyl-5-methyl-2,4-oxazolidinedione CAS Registry No 50471-44-8... 

Related Reagents. (2S,4S)-3-Benzoyl-2-r-butyl-4-methyl-l,3-oxazolidin-5-one t-Butyl 2-t-Butyl-3-methyl-4-oxo-l-imi-dazolidinecarboxylate (/ )-2-t-Butyl-6-methyl-4//-l,3-dioxin-4-one (/ ,/ )-2-t-Buty 1-5-methyl-l,3-dioxolan-4-one Diethyl Acetamidomalonate A/-(Diphenylmethylene)aminoacetonitrile Ethyl A/-(Diphenylmethylene)glycinate Ethyl Isocyanoacetate Methyl A/-Benzylidenealaninate (/ )-Methyl 2-t-Butyl-3(2iiO-oxazolecarboxylate. 

Dimethyl-2-methoxycarbonyl-l-[4-methyl-3-(4-methyl-benzenesul-fonyl)- 5-phenyl-l, 3-oxazolidin-2-yll- 1774... 

S)-3-tert.-Butyloxycarbonyl-2,2-dime thyl-1,3-oxazolidin-4-ylcarbonyl]- 302 2-[(4S/5R)-3-tert.-Butyloxycarbonyl-2,2,5-tri-methyl-l,3-oxazolidin-4-carbonyl]- 302 4-tcrt.-Butyl-2-phcnyl- 187 2-Butylthio- 294 2-Butylthio-5-cyan- 217 2-Carbonylmetallo- 150 Carboxy- 302, 304... 

Poly(y-benzyl-i.-glutamate) macromonomers were synthesized starting with the polymerization of benzyl (S)-3-(2,5-dioxo-l,3-oxazolidin-4-yl) propionate (or y-benzyl-L- glutamate-N-carboxyanhydride [189]) with the primary amino group of the N-methyl-N-(4-vinylphenethyl) ethylene diamine (1) [190] (Scheme 58). 

A mixture of A-Boc-protected amino acid (5 mmol), 195 mg paraformaldehyde (6.5 mmol), and 43 mg /7-toluensulfonic acid (0.25 mmol) in 50 mL benzene was refluxed with the aid of a Dean-Stark trap, and heating was continued until no starting material was detected by TLC (1-3 h). The reaction mixture was cooled to room temperature, washed with 5% KHCO3 (2 X 30 mL) and brine (30 mL), dried, and concentrated. The crude product was purified by column chromatography or by crystallization from suitable solvents. For (45)-A-t rt-butyloxycarbonyl-4-methyl-l,3-oxazolidin-5-one from A-Boc-analine, 825 mg was obtained by crystallization from CH2Cl2-hexane as white needles, in a yield of 82%, m.p. 66-6TC. 

Related Reagents, S or /5 4-Ethyl-l,3-thiazolidine-2 thlone S or 7 4 Methoxycarbonyl-l,3-thiazolidine-2-thlone (. 4 Methoxycarbonyl-l,3-thiazolidine-2-selenone (. 4 MethoxycarbonyTl,3 oxazolidine-2-thione (, -4-Iso-propyTl,3 oxazolIdlne-2 thlone S or 75 4-Ethyl-l,3-oxa-zolldlne 2 thlone (7 4 methyl-(5)-5-Phenyl-l,3-oxazolidine-2 thlone (, -4-(phenylmethyl) l,3-thiazolidine-2-thione, ... 

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. 

In 2007, Frauenrath and Flock described the double bond isomerisation of 5-methyl-4//-l,3-dioxin performed upon catalysis with [Nil2(i ,i )-Me-DU-PHOS], which afforded the corresponding chiral dioxins in excellent enantioselectivities of up to 95% ee, along with good yields (Scheme 10.18). These products were further aziridinated and then ring-opened to lead to chiral 4-methyl-l,3-oxazolidine-4-carbaldehydes with 73% de. 

The 2,2-bis(tnfluoromethyl)-4-methyl-2f/-5-oxazolone, readily available from 2,2-bis(trifluoromethyl)-l,3-oxazolidin-5-one, is a synthetic equivalent of activated pyruvate [90] (equation 16). 

An entry to. yyrt-2-methoxy-3-hydroxycarboxylic acids is also opened using similar methodology. Thus the norephedrine derived (4/ ,5S)-3-(2-methoxy-l-oxoethyl)-4-methyl-5-phenyl-1,3-oxazolidine-2-one 23105a, as well as the phenylalanine derived (4S)-4-benzyl-3-(2-methoxy-l-oxoethyl)-l,3-oxazolidin-2-one 25105b, can be added to aldehydes via the boron enolates to give, after oxidative workup, the adducts in a stereoselective manner (d.r. 96 4, main product/sum of all others). Subsequent methanolysis affords the methyl esters. 

Cyclische 0,N-Acetale vom Typ der 1,3-Oxazolidine und 2,5-Dihydro-l,3-oxazole werden durch Lithiumalanat7 und Natriumboranat8,9 zu 2-Amino-alkoholen reduziert. Aus 3-Methyl-2-phenyl-l,3-oxazolidin wird z.B. mit Natriumboranat 2-(N-Methyl-N-benzyl-amino)-athanol (74% d.Th) erhalten8 ... 

Oxazolidine konnen reduktiv zu 3-Amino-alkanolen gespalten werden, wie die Re-duktion von 2-Methyl-3-phenyl-5-(trimethylsilyl-methyl)- und 2-Phenyl-3-propyl-5-(tri-methylsilyl-methyl)-l, 2-oxazolidin zu 2-Hydroxy-4-metkylamino-4-phenyl-l-trimethylsi-lyl-butan bzw. 4-Anilmo-2-hydroxy-l-trimethylsilyl-heptan zeigt die so erhaltenen Amino-... 

S)-3-(2-Hydroxyethyl)-5-(2-oxo-l,3-oxazolidin-4-ylmethyl)-l-H-indol-2-carboxylicacid methyl ester... 

---