4,4-Dimethyl-2-oxazolidinone

The similar compounds 4,4-dimethyl-2-oxazolidinone 9 and 4,4,5,5-tetramethyl-2-oxazolidmone 10 have been prepared by cydocarbonylation of the corresponding amino alcohols with either diethyl carbonate [8] or GDI [8, 9] as carbonylation reagents (see also Section 4.3.2.4). 

SCHEME 7.16 Cycloaddition reactions of benzonitrile oxide with 3-aciyloyl-4,4-dimethyl-2-oxazolidinone in the presence of PyBOX-Ph-Yb(OTf)3. 

Oxazolidinones. 3-Chloro-4,4-dimethyl-2-oxa2ohdinone [58629-01-9] (10) has been extensively evaluated as a disiafectant (157). It is prepared by phosgenation of (CH2)2CH(NH2)CH20H followed by chlorination ia the presence of caustic. It is a white crystalline soHd with a theoretical av CI2 of... 

C3NO 0 — N — — 2,2 -p-Phenylenebis(5-phenyloxazole) 2-(4-pyridyl)oxazole 2,4-dimethyl-5-(p-nitrophenyl)oxazole 2-oxazolidinone ... 

The desilylacetylated qrcloadducts, produced from the reactions of trimethylsilyl-diazomethane with 3-crotonoyl-2-oxazolidinone or 3-crotonoyl-4,4-dimethyl-2-oxa-zolidinone, were transformed to methyl traws-l-acetyl-4-methyl-l-pyrazoline-5-car-boxylate through the reactions with dimethoxymagnesium at -20 °C. When the optical rotations and chiral HPLC data were compared between these two esters, it was found that these two products had opposite absolute stereochemistry (Scheme 7.39). The absolute configuration was identified on the basis of the X-ray-determined structure of the major diastereomer of cycloadduct derived from the reaction of trimethylsilyldiazomethane to (S)-3-crotonoyl-4-methyl-2-oxazolidi-none. 

Several other oxazolidinones have been developed for use as chiral auxiliaries. The 4-isopropyl-5,5-dimethyl derivative gives excellent enantioselectivity.91 5,5-Diaryl derivatives are also quite promising.92... 

Ring D inversion seems to be a crucial step in biogenetic transformations of protoberberines to related alkaloids such as rhoeadine, retroprotoberberine, spirobenzylisoquinoline, and indenobenzazepine alkaloids. 8,14-Cyclober-bin-13-ol 478 derived from berberine (15) was successively treated with ethyl chloroformate, silver nitrate, and pyridinium dichromate (PDC) in dimethyl-formamide to give the keto oxazolidinone 479 (Scheme 98). Heating of 479 with 10% aqueous sodium hydroxide in ethanol effected hydrolysis, retro-aldol reaction, cyclization, and dehydration to provide successfully the... 

B. (4R,5S)-3-(1-Methoxyethyl)-4,5-diphenyl-2-oxazolidinone. A 2-L, threenecked, round-bottomed flask equipped with a magnetic stirrer, thermometer, and a reflux condenser is charged with (4R,5S)-4,5-diphenyl-2-oxazolidinone (20.0 g, 84 mmol), ( )-10-camphorsulfonic acid (9.7 g, 42 mmol) (Note 7), and acetaldehyde dimethyl acetal (700 mL) (Note 8). The mixture is heated at gentle reflux in an oil bath (bath temperature 80°C) for 5 hr (Note 9). The mixture is allowed to cool to ambient temperature, then concentrated under reduced pressure on a rotary evaporator (Note 10). Ethyl acetate (100 mL) is added to the residue, and the ethyl acetate solution is transferred to a beaker. The solution is neutralized with saturated sodium bicarbonate solution (100 mL) (Note 11), and transferred into a separatory funnel. The two layers are separated, and the lower aqueous layer is extracted with ethyl acetate (100 mL). 

Verma and Ghosh [72] desymmetrized a a-symmetric 3-dimethyl(phe-nyl)silyl substituted glutaric anhydride (127) with Evans oxazolidinone 128 (Scheme 32) as one of the key steps in their synthesis of (+)-preussin. 

Tamariz et al. reported the synthesis of mukonine (11) based on a regioselective Diels-Alder reaction of N-phenyl-4,5-dimethylidene-2-oxazolidinone (634) with methyl propiolate (635). The diene 634 was prepared in moderate yield from the condensation reaction of 2,3-butanedione (632) with phenyl isocyanate (633). In an optimized reaction procedure using drastic basic hydrolytic conditions (KOH/ MeOH), followed by methylation with dimethyl sulfate, the adduct 636, was... 

Cycloaddition to 3-acryloyl-2,2-dialkyloxazolidines (35) proceeded in a highly stereoselective manner (Scheme 6.38) (191), but poorly so when 4-benzyl-5,5-dimethyl-2-oxazolidinone (36) was used as a chiral auxiliary (Scheme 6.39). 

A camphor-based 3-acyl-2-oxazolidinone has also been used for diastereoselective alkylations66. The A-acylated auxiliary 18 is prepared in three steps from 7,7-dimethyl-2-oxobicy-clo[2.2.1]heptane-l-carboxylic acid (ketopinic acid, 17)67. Deprotonation by lithium diiso-propylamide in tetrahydrofuran at — 78 °C and subsequent alkylation with activated halides [(bromo- or (iodomethyl)benzene, 3-bromo- or 3-iodopropene] furnished moderate to good yields of alkylation products in high diastereomeric ratios (>97 3 by H NMR). With added hexamethylphosphoric triamide the alkylation yields are increased and bromoalkanes also give satisfactory yields. The diastereomeric ratios are, however, much lower (d.r. 70 30 to 85 15)67. 

PC propylene carbonate NMO 3-methyl-2-oxazolidinone TBAI tetrabutylammonium iodide AN acetonitrile PN propionitrile GN glutaronitrile MAN methoxyacetonitrile MPN 3-methoxypropionitrile TBP tert-butylpyridine HMIml l-hexyl-3-methylimidazolium iodide DMPIml 1,2- dimethyl-3-propy-limidazolium iodide SOC Sumitomo Osaka Cement Co. Ltd. 

S)-Phenyl-2-oxazolidinone.6 A one-pot route to this chiral auxiliary involves reduction of L-phenylglycine and BF3 etherate in DME with borane-dimethyl sulfide complex at a temperature maintained at 82°. The resulting phenylglycinol is then treated with trichloromethyl chloroformate (or the more expensive triphosgene). 

As an abundant, nontoxic, non-flammable, easily available, and renewable carbon resource, C02 is very attractive as an environmentally friendly feedstock for making commodity chemicals, fuels, and materials [1-7]. In this respect, PEGs-functionalized catalysts have been developed for efficient transformation of C02 into value-added chemicals or fuels such as cyclic carbonates, dimethyl carbonate (DMC), oxazolidinones, organic carbamates and urea derivatives. 

FIGURE 7. DFT calculated structures and population of l,5-dimethyl-2-oxazolidinone lithium enolate431,432... 

BF3-OEt2-mediated condensation of Cbz-pro-tected D-alanine with benzaidehyde dimethyl acetal provides the oxazolidinone 13. Stereoselective alkylation of 13 with bromomethyl ben-... 

However, when a thiocarbonimidate prepared from an acyclic allylic alcohol underwent cyclization, no significant relative 1,2-asymmetric induction was observed [d.r. (cis/trans) 58 42], Structural assignment of the diastereomeric mixture was made by removal of the tcrf-butyl group with trifluoroacetic acid to give 6, followed by cleavage of the C —Br bond with tributyltin hydride, since the stereochemistry of both cis- and rr[Pg.840]

Related Reagents. (5)-4-Benzyl-5,5-dimethyl-2-oxazoli-dinone (5)-5,5-dimethyl-4-ij o-propyl-2-oxazolidinone (5)-5,5-dimethyl-4-methyl-2-oxazolidinone (5 )-5,5-diphenyl-4-ij o-pro pyl-2-oxazolidinone (f )-4-benzyl-5,5-dimethyl-2-oxazolidi-none. 

Related Reagents. The synthesis of chiral diazenedicarboxylates as potential chiral electrophilic aminating agents has received little attention. A series of chiral bomyl, isobomyl and menthyl diazenedicarboxylates has been reported and their reaction with achiral enolates of esters and N,N-dimethyl amides afforded a-hydrazino acid derivatives with little or no selectivity. Incorporation of a chiral azodicarboxamide unit into a chiral bridging binaphthyl moiety afforded a-hydrazino acid derivatives with high stereoselectivity in reactions with achiral oxazolidinone anions. ... 

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