Pyrrolidones, formation

The 4-azidobutyrate ester is introduced via the acid chloride. Gleavage occurs by pyrrolidone formation after the azide is reduced by hydrogenation, H2S or Ph3P. ... 

Reports of five-membered ring formation involving this mechanism remain unauthenticated. Formation of an oxazolidinone product from Ritter reaction of cyclohexanone and cyclohexanone cyanohydrin has been shown by Ducker to result from an alternative pathway. Although 4-methyl-3-pentenonitrile did undergo intramolecular cyclization, this did not involve pyrrolidone formation. Rather a novel dimeric process took place, leading to formation of a monocyclic (74) and a bi-cyclic (75) product. The latter was readily ring opened to (74) using silver oxide and water (Scheme 37). 

In peptides with glutamine as the N-terminal residue spontaneous pyrrolidone formation takes place the reaction is catalyzed by weak acids ... 

Ring closure resulting from attack of a heteroatom on a carboxyl group or its equivalent is merely a case of intramolecular esterification or amide formation. The y-butyrolactones or pyrrolidones obtained from such reactions are usually regarded as the province of aliphatic chemistry, so only a few examples are offered by way of illustration in Scheme 15. 

Most ring syntheses of this type are of modern origin. The cobalt or rhodium carbonyl catalyzed hydrocarboxylation of unsaturated alcohols, amines or amides provides access to tetrahydrofuranones, pyrrolidones or succinimides, although appreciable amounts of the corresponding six-membered heterocycle may also be formed (Scheme 55a) (73JOM(47)28l). Hydrocarboxylation of 4-pentyn-2-ol with nickel carbonyl yields 3-methylenetetrahy-drofuranone (Scheme 55b). Carbonylation of Schiff bases yields 2-arylphthalimidines (Scheme 55c). The hydroformylation of o-nitrostyrene, subsequent reduction of the nitro group and cyclization leads to the formation of skatole (Scheme 55d) (81CC82). 

Bonnett et alJ observed the formation of the pyrrolidone hydrox-amic acid (66) as a by-product in the alkaline hydrolysis of a 2-cyano-nitrone (69). This displacement of cyanide by hydroxyl seems to be quite general. 

During a study of azonitrones (70), Forrester and Thomson showed that reaction with toluene-p-sulfinic acid resulted in nitrogen evolution and formation of the hydroxamic acid (66) together with the pyrrolidone (71) and the amidine (72). These workers suggested the following reaction course. Although the yield of hydroxamic acid was high, the method is not likely to be of preparative value. 

In the photoaddition of 2-pyrrolidone the 5-alkyl isomer (69) always predominates, usually in a ratio of 2 1. The formation of anti-Markovnikov 1 1 adducts, telomers, and dehydrodimers of structure (71) supports a free radical mechanism. Similarly, formamide undergoes olefin addition under... 

Acrylic acid diallylamide is transformed by palladium chloride into A3-pyrrolinone derivatives but the synthetic utility of this type of cyclization is limited because of the formation of a complex product mixture containing pyrrolidones (Scheme 37).65... 

Kitano S, Kataoka K, Koyama Y et al (1991) Glucose-responsive complex formation between poly (vinyl alcohol) and poly(lV-vinyl-2-pyrrolidone) with pendent phenylboronic acid moieties. Makromol Chem Rapid Commun 12 227-233... 

The change of the spectral characteristics, as well as the fact of the dissolution of fullerene C in water with PVP itself, confirms the formation of interaction between the fullerene and PVP, most probably of a donor-acceptor type. According to the NMR 13C data in D20 the electronic state of carbon atoms C(1) and C(4) of pyrrolidone cycle and C(5) of monomer unit of PVP, nearest to nitrogen atom, cardinally changes in the complex (Vinogradova et al., 1998). 

Photolysis or thermolysis of heteroatom-substituted chromium carbene complexes can lead to the formation of ketene-like intermediates (cf. Sections 2.2.3 and 2.2.5). The reaction of these intermediates with tertiary amines can yield ammonium ylides, which can undergo Stevens rearrangement [294,365,366] (see also Entry 6, Table 2.14 and Experimental Procedure 2.2.1). This reaction sequence has been used to prepare pyrrolidones and other nitrogen-containing heterocycles. Examples of such reactions are given in Figure 2.31 and Table 2.21. 

Nitrosamine formation is not the only conceivable fragmentation mechanism for compounds of structure I. By analogy to the nitrosative dealkylation reactions discussed above, one might predict that such compounds could also undergo cis elimination of nitroxyl in amide-forming reactions. Such a transformation has possibly been observed (14). During an attempt to synthesize the nitrosamino aldehyde VIII from immonium ion IX, Hecht coworkers were able to isolate only 5-10% of the desired product. The major product proved to be N-methyl-2-pyrrolidone, as shown in Fig. 10. We interpret this as evidence that an intermediate such as li can fragment not only by the Fig. 1... 

Because of acid-catalyzed hydrolysis of N-vinylpyrrolidone in water, polymerization was carried out in organic solvent - DMF. Three types of samples of poly(methacrylic acid) were used syndiotactic - obtained by radiation polymerization, atactic - obtained by radical polymerization, and isotactic - obtained by hydrolysis of isotactic poly(methyl methacrylate). It was found that in all cases the rate enhancement appeared in comparison with the blank polymerization (without template). The rate enhancement became more pronounced with increasing chain length and syndiotacticity of the template. According to the authors, the rate enhancement is connected with the stronger complex formation between poly(vinyl pyrrolidone) and syndiotactic poly(methacrylic acid) then with isotactic template. This conclusion was supported by turbimetric titration in DMF/DMSO system and by model considerations. It is worth noting, however, that... 

A similar procedure was described by Eboatu and Ferguson. An object of analysis was the complex obtained by template polymerization of acrylic acid in the presence of poly(vinyl pyrrolidone). The polycomplex was dispersed in dry benzene and treated with diazomethane. The insoluble portion was filtered. The filtrate containing poly(methyl acrylate) was concentrated and finally dried. The insoluble fraction was scrubbed with methanol to extract polyCvinyl pyrrolidone). The residue was further washed with methanol and then dried. These three portions were characterized by IR spectroscopy. It was found that only about 70% separation of the complex is achieved. The occurrence of inseparable portion is attributed to a graft copolymer formation. For the separated... 

Formation of the enolate from 1-methyl-2-pyrrolidone (a y-lactam) is accomplished by treatment with lithium diethylamide in hexamethylphosphoric triamide/benzene at — 20 °C. Addition of bromomethane or (chloromethyl)benzene then results in good yield of the a-alkylation product15. 

In conclusion, the order of reduction of metal ions is controlled by their redox potential. This is also true in other pairs of precious metals such as Pd/Pt, Au/Pd, etc. (53). In addition, poly(jV-vinyl-2-pyrrolidone) (PVP) plays an important role for the formation of the core/shell structure. In the case of the Au/Pt system, the aggregation starts from Au but not Pt. This is probably due to the coordinating ability of metals to PVP. The Pt atoms or microclusters coordinating to PVP are more stable than the Au atoms or microclusters, since Au cannot coordinate to PVP. Thus, Au atoms or microcluster aggregate at first after the reduction, and then Pt atoms or microclusters deposit on the Au nuclei. In summary, the core/shell structure is controlled by (1) the redox potential of metal ions, and (2) the coordination ability of metals to PVP, stabilizing polymer. 

As a t rpical example. Scheme 3 shows the possible formation of five-membered ring systems with two heteroatoms in the aceto-in-ammonium sulfide model system (Barone, R., Universite d Aix-Marseille III, unpublished results, 1986). Similar predictions can be made for the formation of substituted pyrrolidones and for additional five- and six-membered rings. 

Interpolymer complexation between water-soluble polymers by hydrogen bonding was a frontier subject in the 1970s. Polyfcarboxylic acids), mainly po-lyfacryhc acid) (PAA) and poly( methacryflc acid) (PMAA), served as the most common proton-donating components. As for the proton-accepting polymers, poly(ethylene oxide ) (PEO or PEG) and poly(M-vinyl-2-pyrrolidone) (PVPo) were often used. The important results on the formation of complex aggregates and its dependence on the structur prameters have been reviewed [2,3,8]. In this section we select a few representative topics to look at recent advances in interpolymer complexes in aqueous media, with the emphasis on fluorescence probe studies. 

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