L,3-Dimethyl-2-imidazolidinone

Recently, use of LiCl/DMAc and LiCl/l,3-dimethyl-2-imidazolidinone as solvent systems for acetylation of cellulose by acetic anhydride/pyridine has been compared. A DS of 1.4 was obtained the substituent distribution in the products synthesized in both solvents was found to be the same, with reactivity order Ce > C2 > C3. Therefore, the latter solvent system does not appear to be better than the much less expensive LiCl/DMAc, at least for this reaction. It appears, however, to be especially efficient for etherification reactions [178]. It is possible, however, that the effect of cellulose aggregation is more important for its reaction with the (less reactive) halides than with acid anhydrides this being the reason for the better performance of the latter solvent system in ether formation, since it is more efficient in cellulose dissolution. 

The amount of molecular sieves 4 A largely influences the product s ee[11]. Usually 100 mg (for the CMHP oxidation) or 1 g (for the TBHP oxidation) of MS 4A for 1 mmol of substrate is enough however, in the case where chemical yield and/or optical yield are not high, use of excess MS 4A often improves them. The addition of achiral ligands such as tributylphosphine oxide, tri-o-tolyl- and tri-/)-tolylphosphine oxides, hexamethylphosphoric triamide, triphenylpho-sphate, lutidine N-oxide, and l,3-dimethyl-2-imidazolidinone were found to be less effective than that of triphenylphosphine oxide in the epoxidation of chalcone. 

The electrochemical process developed using Pb electrodes in aqueous sulphuric acid yields a practical procedure for m-hydroxv-benzyl alcohol (14). Yields up to 88% of (16) were achieved using l,3-dimethyl-2-imidazolidinone... 

Not only a zinc-copper couple, but also a zinc-lead couple forms a gem-dimetal species from diiodomethane, according to the 1975 Nysted patent5. He also insisted that treatment of dibromethane with a zinc-lead couple in THF at 80 °C forms a characteristic gem-dizinc species 1 (equation 3). However, there was no further evidence concerning the structure except H NMR data, which was not enough for the complete structural determination. The obtained compound was definitely a gem-dizinc species, but the written structure 1 was not fully characterized. The white solid 1 is obtained as a dispersion in THF, and does not dissolve in DMF and DMI (l,3-dimethyl-2-imidazolidinone). This THF dispersion is commercially available from Aldrich Co. as Nysted reagent. Nysted also showed that this dizinc compound is effective for the methylenation of a-hydroxy ketone moiety in steroid derivatives5. 

Homoallylic alcohols. Allyl iodide reacts wth SnF2 to form in situ allyltin difluoroiodidc, which reacts with aldehydes to form homoallylic alcohols in yields of 80-90%. The reaction with ketones proceeds in lower yield. l,3-Dimethyl-2-imidazolidinone is the most satisfactory solvent. SnCl2 and SnBr2 can be used, but yields are somewhat lower. 

Nucleophilic bis-O-demethylation of dimethoxybenzenes in one flask is often difficult. It can, however, be achieved by use of sodium TMS thiolate in l,3-dimethyl-2-imidazolidinone (DMEU) at high temperature in a sealed tube101. The same reagent system converts nitriles into primary thioamides at or slightly above room temperature in varying yields102. 

Aryl nitriles with (Me3Si)2S in the presence of MeONa/l,3-dimethyl-2-imidazolidinone results in the conversion to primary thioamides, while amides and lactams yields the thio derivative using (Me3Si)2S and an oxophilic promoter such as POCI3, triphosgene or oxalyl chloride. Thus the intermediate [CIRC=NR R"]+C1 reacts with the silthiane to give the thioamide (equation 24)44. 

Homoallylic alcohols.2 SnF2 and allyl iodide form an allyltin difluoroiodide, which reacts with carbonyl compounds in l,3-dimethyl-2-imidazolidinone to form homoallylic alcohols (equation 1). 

Oku A, Tomari K, Kamada T, et al. 1995. Destruction of PCCDs and PCDFs. A convenient method using alkali-metal hydroxide in l,3,-dimethyl-2-imidazolidinone (DMI). Chemosphere 31(8) 3873-3878. 

The reaction of pentachloropyridine (348) with an excess of benzenethiolate ions in l,3-dimethyl-2-imidazolidinone as solvent leads to complete halogen replacement pen-takis(phenylthio)pyridine (349) and l,3,4-tris(phenylthio)[l]benzothieno[3,2-c]pyridine (350) were thus formed (equation 204)345. 

Alkynylsilanes can be converted into alkynylcoppers by treatment with Cu salts in an aprotic polar solvent such as l,3-dimethyl-2-imidazolidinone (DMI).62 The Cu-promoted coupling reactions via the Si-Cu transmetallation of alkynylsilanes are valuable for the syntheses of alkynyl ketones, 1,3-diynes, 1,3-enynes, and 1-aryl-l-alkynes from acid chlorides,62 alkynyl chlorides,63 alkenyl iodides,64 and aryl iodides,64 respectively (Equation (12)). In addition, symmetric 1,3-diynes can be prepared by the CuCl-mediated homocoupling of alkynylsilanes.65 653... 

The selenadiazoline 16 is thermally stable up to 105 °C, its melting point in the dark. Thermolysis of 16 without a solvent at 115-130°C or in refluxing l,3-dimethyl-2-imidazolidinone (DMI) gave the desired cyclohexene 67 in 43% and 7% yield, respectively, as colorless crystals (Scheme 1) <2002HAC351>. 

All chemieals were of reagent grade. Catalytic experiments were carried out in a 50 mL hastelloy autoclave. Typically, a l,3-Dimethyl-2-imidazolidinone (DMI) solution (10 mL) of Ru3(CO)i2 (0.067 mmol), Co2(CO)g (0.200 mmol) and Lil (5.0 mmol) was placed in the autoclave, into which CO2 (20 atm) and H2 (100 atm) were introduced with stirring at room temperature. The reactor was then heated at 180 °C for 15 h. After the reaction, the reactor was cooled to room temperature and depressurized. The products were quantitatively analyzed by gas chromatography. 

The nature of the solvent used to prepare the solution (e.g., water, dimethylformamide, dimethylacetamide, l,3-dimethyl-2-imidazolidinone (DM1)), equilibration temperature, the ratio between the gas phase and the liquid phase and the possible need to promote a sdting out effect by adding mineral salts are the parameters, amongst others, which should be investigated and optimized to improve the sensitivity (LOD, LCXJ) of the method. " ... 

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