L-methyl-2-pyrrolidone

As reported by Padwa and coworkers, exposing a suitable nitrofuran precursor to microwave irradiation in l-methyl-2-pyrrolidone (NMP) in the presence of 2,6-luti-dine catalyst provided l,4-dihydro-2H-benzo[4,5]furo[2,3-c]pyridin-3-one as the major product in 36% yield (Scheme 6.236) [419]. In contrast, under thermal conditions, removal of the tert-butyl group was observed as the major reaction pathway. 

For example, many microwave-assisted solid-phase coupling reactions utilize l-methyl-2-pyrrolidone (NMP) or 1,2-dichlorobenzene (DCB) as the reaction solvent. The main reason for this is the high thermal stabilities of these solvents and their... 

As far as polymer supports for microwave-assisted SPOS are concerned, the use of cross-linked macroporous or microporous polystyrene (PS) resins has been most prevalent. In contrast to common belief, which states that the use of polystyrene resins limits reaction conditions to temperatures below 130 °C [14], it has been shown that these resins can withstand microwave irradiation for short periods of time, such as 20-30 min, even at 200 °C in solvents such as l-methyl-2-pyrrolidone or 1,2-dichlorobenzene [15]. Standard polystyrene Merrifield resin shows thermal stability up to 220 °C without any degradation of the macromolecular structure of the polymer backbone, which allows reactions to be performed even at significantly elevated temperatures. 

In a more recent study using dedicated multimode microwave reactors for chemical synthesis, which enable temperature and power control, it was demonstrated that microwave irradiation could be effectively employed to couple aromatic carboxylic acids to polystyrene Wang resin [25], if the symmetrical anhydride procedure was used, and not the three-component O-acylisourea activation method [19]. Almost quantitative loading was achieved in l-methyl-2-pyrrolidone (NMP) at 200 °C within 10 min under... 

H.M. Solomon, B.A. Burgess, G.L. Kennedy, R.E. Staples, l-Methyl-2-Pyrrolidone (NMP) reproductive and developmental toxcicity study by inhalation in the rat, Drug and Chemical Toxicology, 18 (1995) 271-293. 

The technically most important polysulfide is poly thiophenylene or poly(p-phe-nylene sulfide), PPS. It is obtained by reacting sodium sulfide and p-dichlo-robenzene in a polar solvent, for example, l-methyl-2-pyrrolidone at about 280 °C under pressure. The mechanism of the reaction is very complex and cannot be described by a simple aromatic substitution. This synthesis requires special autoclaves and is therefore not suitable for a laboratory course (for an experimental procedure see Table 2.3). 

Sometimes, mixture of solvents with water have been employed, probably with the aim of improving the phase transfer. These mixtures include ethanol/watcr,107 acetic acid/water.42-108 dioxane/water,109 diethyl ether/water, 10111 and tetrahydrofuran/water.46 Other solvent mixtures, e.g, ethanol/ dioxane,112 ethanol/diethyl ether, 3 diethyl ether. hexane,113 and dimethyl sulfoxidc/l-methyl-2-pyrrolidone,102 have been used in selected cases, with no given reason. 

The reaction of 1-methyl-2-(methylmercapto)-2-pyrroline (282) with DMAD is known to give a dihydroazepine derivative (283) (Eq. (38)].167 The recent report of the reaction of l-methyl-2-pyrrolidone dimethyl-acetal (284) with DMAD to give products like 286, 287, 288, and 289 may be interpreted as essentially the reaction of the enamine system (285) (Scheme 45).161 Other examples of the reaction of enamines include the reaction of the pyrrolidinopentenone (290) to give the phthalate (293)... 

Fig. 3. Solvent effect on the yield of 2-phenylpyrrole [89KGS29I] I, DMSO 2, HMPA 3, l-methyl-2-pyrrolidone 4, sulfolane 5, PEG 6. tetramethyl urea. Catalyst KOH (0.5 mol/L), for other reaction conditions see Fig. 1.

Figure 3 presents kinetic curves for the formation of 2-phenylpyrrole (Scheme 2) at 96°C and atmospheric C2H2 pressure in various solvents such as DMSO, HMPA, l-methyl-2-pyrrolidone, sulfolane, polyethyleneglycol (PEG) with Mm = 1000, and tetramethylurea [89KGS770]. DMSO is confirmed to possess a specific catalytic effect in this reaction, which is much superior to that of HMPA, l-methyl-2-pyrrolidone, and tetramethylurea. According to their capability to catalyze the formation of 2-phenylpyrrole from acetophenone oxime and acetylene, the solvents under consideration are arranged in the following order DMSO > HMPA l-methyl-2-pyrrolidone > sulfolane > PEG > tetra-... 

The homopolymerization of DADMAC is possible in several organic solvents such as acetone, l-methyl-2-pyrrolidone, tetramethylurea, or dimethylform-amide. Various initiation methods including radical, ionic, or x-ray induced polymerization have been employed [19]. Since the monomer solubility is limited in these solvents, and the resulting homopolymer is soluble only in water, methanol and acidic acid, the polymerization in aqueous solutions are preferred. Polymerization in both homogeneous and heterogeneous systems have been studied and the kinetics and mechanisms were investigated in aqueous solution and in inverse-emulsion [6-16,52,53]. 

Paint remover Acetone, l-methoxy-2-propanol, 8 2-(2-methoxyethoxy)-ethanol, l-methyl-2-pyrrolidone, C2-C6-benzenes... 

Others 1,4-dioxane, 1,3,5-trioxane, terahydrofuran, 2-butyl tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, epsilon-caprolactam, benzothiazole, biphenyl, pyrazine, 2-butanone oxime, l-methyl-2-pyrrolidone, N,N-dimethyl-aniline, N,N-dimethyl-p-toluidine, l-methyl-7-isopropyl phenanthrene, dibenzyl-amine, hexamethylenetetramine, squalene, 2-ethylanthraquinone... 

Dendrobium Alkaloids.—A third synthesis of shihunine, the principal base of several Dendrobium spp., has been reported. It involves allowing the dilithio-anion (12) to react with l-methyl-2-pyrrolidone (13), to yield ( )-shihunine (14) in 23% yield.11 Full experimental details pertaining to a synthesis of ( )-dendrobine, reported briefly earlier, have been described.12... 

Auch cyclische Carbonsaure-amide sind der beschriebenen Reaktion [phosphorige Sau-re/Phosphor(III)-chlorid]zuganglich4 aus l-Methyl-2-pyrrolidon erhalt man in 41%iger Ausbeute l-Methyl-pyrrolidin-2,2-diphosphonsaure (Schmp. 207°). 

As in benzenoid chemistry, some nucleophilic displacement reactions can be copper catalyzed. Illustrative of these reactions is the displacement of bromide from 3-bromothiophene-2-carboxylic acid and 3-bromothiophene-4-carboxylic acid by active methylene compounds (e.g., AcCH2C02Et) in the presence of copper and sodium ethoxide (Scheme 136). Analogously, 2-methoxythiophene can be prepared in 83% yield by refluxing 2-bromothiophene in methanol containing excess sodium methoxide, along with copper(I) bromide as catalyst. For the analogous preparation of 3-methoxythiophene, addition of a polar cosolvent (e.g., l-methyl-2-pyrrolidone) is beneficial. In the case of halothiophenes, an SrnI mechanism is involved. 

H-ZSM-5 impregnated with Cr catalyzes syntheses of five- and six-membered heterocycles. For example, T butyrolactone and methylamine are converted to l-methyl-2-pyrrolidone with 98.2% yield [80]. 

Special solvent. Newman - recommends N-methyl-2-pyrrolidone as solvent for the reaction of an aryl halide with cuprous cyanide to produce the corresponding nitrile. Dimethylformamide (b.p. 153°) has been suggested as a better solvent than originally used pyridine (b.p. 115°), but l-methyl-2-pyrrolidone has an even higher boiling point and seems still more satisfactory. An example is the synthesis of... 

Henbesf found l-methyl-2-pyrrolidone superior to other aprotic solvents tried for nucleophilic displacement of the tosylate group. In the conversion of the tosylate (1) of cholestane-3/8-ol into 3a-cyanocholestane (2) the best yield was obtained in... 

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