1- pyrrolidine-2,5-dione oxidant

At the beginning of the oxidation, l-pentyl-2,5-pyrrolidine dione was found only at trace levels, but after 1,200 h, its relative peak area had increased drastically, making it the most abundant degradation product. The increase was the same for both virgin and recycled materials. Substantially more 1-pentyl-2,5-pyrrolidine dione was formed from the recycled materials than from the virgin material. 

Figure 2.3 Loss of tensile strength versus the formation of l-pentyl-2, 5-pyrrolidine dione during 1,200 h of thermo-oxidation of (a) virgin and (b) once recycled PA 6,6 at 100 °C. Reproduced with permission from M. Grdning and M. Hakkarainen,/oMrn t/ of Applied Science, 2002, 86 13, 3396 2002, Wiley...

A variety of mono- and bi-cyclic /3-lactams have also been prepared by oxidative ring contraction of pyrrolidine-2,3-diones (180) (75JOC2356), and by the photolysis of pyrazolidin-3-ones (181) (78T1731, 75JOC3510, 75JOC3502, 75CC725). 

IV-acetyl pyrrolidines and -piperidines to the corresponding diones or ketones were similarly effected [405, 406], as were conversions of diacetyl and dibenzyl piperazines to diketo componnds by the same system (Table 5.1) [407]. Methylene groups adjacent to the N atom in tertiary polycyclic amines were oxidised by RuO /aq. NaCIO j/CCl (Fig. 5.5) [408]. A large-scale oxidation of l,4-bis(2-phenylethyl) piperazine to the dione was made by RnO /aq. Na(10 )/Et0Ac [409], and RuO /aq. Na(IO )/CCl converted dialkyl or diaryl A A -dimethyladenosines to the corresponding monoamido derivatives (Fig. 5.4) [410]. 

Formation of an enamine radical cation 45 was proposed as the chain initiation step in the autooxidation of enamines and SchifFs bases of a,/ -unsaturated ketones to give unsaturated 1,4-diones37. Pyrrolidine enamine of 10-methyl-A1(9)-octal-2-one (44) reacts with oxygen at room temperature to produce, after acid hydrolysis, 10-methyl-A1 (9)-octalin-2,8-dione (47) in 20% yield. Addition of a catalytic amount of FeCl3, Cu(OAc)2 or CuCl2 causes a pronounced enhancement in the oxidation rate and increases the yield to 80-85% after 1 h. 

Allyl cyanide 445 have been oxidized to yield the corresponding amide derivative 446 in 82% yield, which then afforded the 3-benzylidene-pyrrolidine-2,5-dione 447 in 78% yield upon treatment with sodium hydride (Scheme 4.138). ... 

Lewis acid, In(0CF3S02)3, catalysed allylic C—H oxidation of aryl cycloalkenes by l-(propyl thio)pyrrolidine-2,5-dione in the presence of CH2CI2 and various nucleophiles (ROH, RCO2H, RSO2NH2) resulted in the formation of allylic ethers, esters, and sulfonamides in 52-83% yields electron-rich substrates were the most reactive. Other aryl cycloalkenes such as 1-naphthyl, l-(3-thiophenyl)-cyclohexene, 1-phenylcycloheptene, and 1-phenylcyclopentene were suitable substrates. Mechanistic studies showed that the sulfenamide played an important role in converting the allyl sulfide intermediate into the products. ... 

Tetramic acids with a pyrrolidine-2,4-dione ring system 90 represent an interesting class of azaheterocycles, which are present as a core structural unit in many natural products endowed with promising biological activihes. A nontoxic and mild I(III) oxidant, PhI(OPiv)2, was successfully utilized for the intramolecular sp C-H aminations of 1-acetyl N-aryl carboxamides 89 to furnish a series of tetramic acid derivatives (Scheme 17) [33]. 

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