4- methylene oxazolidinone

Propargyl alcohol (332) and (328) react readily with isocyanates in the presence of a basic catalyst to give 4-methylene-2-oxazolidinones (334) and 4-methylene-2-imidazolinones (336), respectively (63JOC991). In the absence of sodium methoxide the intermediate methanes (333) and ureas (335) were obtained and on treatment with sodium methoxide underwent ring closure. Moderate to excellent yields were obtained. 

Dehydration of 4-hydroxy-4,5,5-trimethyl-2-oxazolidinone 301 with a catalytic amount of p-toluenesulfonic acid affords the isomeric dimers 303 and 304 in a ratio of 1 2. The former type of dimer, that is, 303 likely results from coupling of the isomeric 2(5//)-oxazolone 302A with 4-methylene-2-oxazolidinone 302B, which are the initially formed dehydration products. On prolonged heating in CH2CI2, the 2(5//)-oxazolone dimer 303, completely isomerizes to the 4-methylene-2-oxazoh-dinone dimer 304 (Fig. 5.77). " ... 

Methyl-1,3-diisopropylpseudourea, 170 Methylene compounds, nitrosation of, 395 4-Methylene-2-imidazolidinones, 140 4-Methylene-2-oxazolidinones, 140 2-Methyl-5-ethylpyridine, 96... 

Ionic liquids have also been found to be efficient reaction media for the activation of CO2 [82-84]. Diurea derivatives are easily obtained from amines and carbon dioxide with a CsOH/ionic liquid catalyst system [83]. N-Substituted 4-methylene-2-oxazolidinones are also efficiently synthesized in IL media by reaction of carbon dioxide with propargylic alcohol and different amines [82]. Other examples include the cycloaddition of CO2 to epoxides to produce cyclic carbonates [85] and synthesis of cyclic urethanes [86,87]. 

Q. Zhang, F. Shi, Y. Gu, J. Yang, Y. Deng, Efficient and eco-friendly process for the synthesis of N-substituted 4-methylene-2-oxazolidinones in ionic liquids. Tetrahedron Lett. 46 (2005) 5907-5910. 

SCHEME 3 7 Synthesis of N-substituted 4-methylene-2-oxazolidinones using [BMIM] [BFJ. 

Hydroxyoxazolidin-2-ones 55 result from the action of aryl isocyanates on the hydroxy ketones 54 (94JPR509). N-acetyl-alanine, valine or leucine and dimethylformamido/ phosphorus oxychloride yield the (formyl-methylene )oxazolidinones 56 (R = Me, i-Pr or... 

Chemical Name 3-[ [(5-nitro-2-furanyl)methylene] -amino] -2-oxazolidinone Common Name —... 

Nonbranched amino acids substituted by a fluoroalkyl chain on a carbon distant at least one methylene from the amino acid function have been prepared as racemates by various methods." Under nonracemic form, co-perfluoroalkyl norvaline and norleucine (Rf = C2F5 or more) have been prepared by bromination of an anion of a fluorinated chiral oxazolidinone (derived from RfCH2CH2C02H). Substitution of the bromine atom by an azide and subsequent reduction yield the desired amino acids (Figure 5.10)." ... 

Yamamoto and co-workers (135,135-137) recently reported a new method for stereocontrol in nitrile oxide cycloadditions. Metal ion-catalyzed diastereoselective asymmetric reactions using chiral electron-deficient dipolarophiles have remained unreported except for reactions using a-methylene-p-hydroxy esters, which were described in Section 11.2.2.6. Although synthetically very useful and, hence, attractive as an entry to the asymmetric synthesis of 2-isoxazohnes, the application of Lewis acid catalysis to nitrile oxide cycloadditions with 4-chiral 3-(2-aIkenoyl)-2-oxazolidinones has been unsuccessful, even when > 1 equiv of Lewis acids are employed. However, as shown in the Scheme 11.37, diastereoselectivities in favor of the ffc-cycloadducts are improved (diastereomer ratio = 96 4) when the reactions are performed in dichloromethane in the presence of 1 equiv of MgBr2 at higher than normal concentrations (0.25 vs 0.083 M) (140). The Lewis acid... 

We added the acetylene to aldehyde 12 now because this step is not compatible with a protected guanidine. Treatment of 43 with EtMgBr to form the acetylide and addition of aldehyde 12 afforded 54% of 45 and 32% of 44. Under the basic conditions, the secondary amine adds to the carbamate to form the oxazolidinone ring. The decrease in the geminal coupling constant of the methylene hydrogens adjacent to the nitrogen from 11 Hz in 43 to 8 Hz in oxazolidinone 45 is characteristic of the... 

Die Methylprotonen der 2-Methyl-4-aralkyliden-A2-oxazolinone-(5) kon-nen gegen Elektrophile ausgetauscht werden. Als reaktive Zwischen-stufen diirften dabei die 2-Methylen-4-aralkyliden-A2-oxazolidinone-(5) (109) eine Rolle spielen. 

Diels-Alder reactions of (Z)-A -substituted-4-methylene-5-propylidene-2-oxazoli-dinone dienes with methyl vinyl ketone, methyl propiolate, and captodative alkenes yield the highest regio- and stereo-selectivities in mixtures of H20 and MeOH or under BF3.Et20 catalysis.198 The asymmetric Diels-Alder reaction of cyclopentadiene and 3-acryloyl-2-oxazolidinone is catalysed by a new Cu(II) catalyst containing a chiral sterically congested roofed (2-diphenylphosphino)phenylthiazoline ligand (169).199... 

The circular dichroism of cis- and trans- 2-oxazolidinones (59 R = H or Me) has been measured (79T2009). Geometrical isomerism round the exocyclic double bond in 4-(aryl-methylene)-5-(4//)-oxazolones (60), the unsaturated azlactones, is a well-studied phenomenon (75S749). It has been shown by X-ray crystallography (74T351) that the stable form of 4-benzylidene-2-phenyl-5(4//)-oxazolone has the (Z) configuration (61). It isomer-izes to the labile (E) form (62) in polyphosphoric acid and the change is reversed in pyridine. 

NITRO-2-FURANYL)METHYLENE)AMINO)-2-OXAZOLIDINONE see NGG500 2((5-NITRO-2-... 

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