A -Acetylpyrrolidine

Chemoselective anodic methoxylation at a distinct carbon atom in the a-position to an amino group in a polypeptide was achieved by prior introduction of a silyl group as an electroauxiliary at this carbon atom [156]. Amide oxidation in A-acetylpyrrolidines substituted with electron-rich phenyl rings led to either methoxylation a to the nitrogen atom or in the benzylic position. Mechanistic studies indicate that both the amide and the phenyl oxidation compete, but intramolecular electron transfer leads to... 

In addition to carbon-based radicals, other radicals such as sulfur-based radicals, generated from an RSH-type precursor (R = alkyl, acyl) with AIBN also smoothly added to allylglycine.4 Optimal results were obtained when both the unsaturated amino acids and RSH dissolved completely in the reaction medium (dioxane-water or methanol-water were found to be superior solvents). Radical additions of thiophenol to carbon-carbon multiple bonds and radical cyclisation of A-allyl-2-iodoalkanamide in aqueous media proceeded smoothly to the A-acetylpyrrolidine derivative in 96% yield. Under similar... 

Pyrrolidine Acetyl chloride A/-Acetylpyrrolidine (79%) Pyrrolidine hydrochloride... 

A stereoselective total synthesis of dendrobatide toxin 251 D was developed by Overman et al.237) involving an epoxidation of the (S)-proline derivative (237) to furnish the oxirane (238) as major product. In their approach towards the total synthesis of the same natural product Thomas et al.238) investigated the stereoselectivity of the epoxide formation from (S)-5-acetylpyrrolidin-2-one and dimethyloxosulfonium methylide. A diastereoselectivity of d.s. 50-60% was achieved 238. ... 

Stock solutions of 1-acetylpyrrolidine, and an internal standard (1-propionylpyrrolidine or 1-methylnaphthalene) in dioxane at a concentration of 10 mg ml-1 are prepared. A mixture of 1ml each of the 1-acetylpyrrolidine and internal standard solutions is used to establish the GC response factor. The calibration is made by injecting a 2-/A aliquot of the mixture into the gas chromatograph and measuring the peak areas. 

The acetylated lignin, dissolved in 1.0 ml of dioxane containing 5 mg of an internal standard, is treated with 1.0ml of a dioxane-pyrrolidine (1 1, v/v) solution which initiates the aminolysis reaction. The rate of the 1-acetylpyrrolidine formation is followed by periodically injecting 1-2/d of the reaction mixture into the gas chromatograph. The initial rapid phase is generally complete within 20 min, but a total of 60min is required to complete the deacetylation process. 

Fig. 7.2.1A,B. Rate of formation of 1-acetylpyrrolidine on A aminolysis of acetylated wood meal Norway spruce and of methanol on B periodate oxidation of wood meal. (Lai et al. 1990)...

The rate of 1-acetylpyrrolidine formation is followed as in the case of acetylated lignin, but the overall process is much slower and a 6-7-h reaction period may be required as illustrated in Fig. 7.2.1A for Norway spruce wood meal. 

A comparison was made between the mechanisms of action of the PVC costabiliser N-phenyl-3-acetylpyrrolidin-2,4-dione and existing costabilisers. The results obtained demonstrated that the performance of short-term costabilisers in calcium/zinc formulations was linked to their ability to complex zinc stearate prior to the initiation of degradation and that this prevented the early formation of prodegradant zinc chloride. 6 refs. 

An interesting variation in the stereochemistry of addition of dimethyloxosulphonium methylide to 5-acetylpyrrolidin-2-one is produced by the addition of anhydrous ZnCl282. In the absence of the salt a 78 22 mixture of epoxides (47 a-Me) and (47 -Me) results, whereas, with added ZnCl2, this ratio changes to 23 77-... 

When a benzene solution of complex 8 (0.1 mol%) containing pyrrolidine and ethyl acetate was refluxed under an argon atmosphere, quantitative conversion of pyrrolidine was observed by GC after 28 h, and N-acetylpyrrolidine was isolated in 98% yield (Table 1.10, entry 1). The same results were obtained when the reaction was carried out in refluxing toluene. The scope of the ester amidation reaction was explored with various esters and amines, and the results are summarized in Table 1.10. 

Af-Allylacetamide as a substrate directs the hydroformylation in the P-position of the amide group, which is explained by coordination ofthe amide unitto rhodium (Scheme 4.38) [32]. The preferred formation of an intermediate six-membered metaiiacycie (A) forces the production of the branched aldehyde. Noteworthy, the terminal aldehyde that is formed via the seven-membered ring B after formation of a hemi-aminal and dehydration may undergo a second hydroformylation step to eventually produce l-acetylpyrrolidine-2-carbaldehyde [82]. 

Acetylpyrrolidines may be prepared from 5-methyl-5-vinyloxazolidines via a reaction which involves a directed sigmatropic rearrangement as shown in Scheme 73. The procedure allows a ready synthesis of l-azaspiro[4,5]decanes." ... 

In intramolecular additions, enolates often tend to act as 0-nucleophiles. In intermolecular reactions, however, it is rather C-C bond formation that prevails. The reaction between of iodobenzene and phenyllithium in the presence of the lithium enolates of /ert-butyl acetate or JV-acetylpyrrolidine represents a typical case. The liberated dehydrobenzene and the enolate combine to afford a C-acylated aryllithium that is converted intoderivative 295 by iodine transfer from iodobenzene. (Scheme 1-232). ... 

---