2- pyrrolidine- 1-carboxylate alkene

The addition of alkyl radicals to less reactive alkenes becomes more efficient if the addition is conducted intramolecularly. The Kolbe electrolysis of A 7- and A -unsaturated carboxylates produces five-and six-membered rings in a 5- or 6-cj o-rng-cyclization. ° Such a cyclization was first observed by Weedon and later studied in more detail." By intramolecular addition of appropriate precursors, 3-substituted tetrahydrofurans (Scheme 10 40, 41%), pyrrolidines (41, 53%), and cyclopentanes (42, 74%), and (43, 75%) are obtained. In the reactions leading to cyclopentanes the extent of cyclization... 

HeterocycUzation. Captodative radicals are generated from a-heterosubstituted a-chloroacetic esters by treatment with CuCl bipy. Such a radical can be trapped in-tramolecularly by an alkene (e.g., a 3-butenyl group) attached to the a-heteroatom. Formation of five-membered ring heterocycles is a favorable process. Thus methyl 3-chloromethyltetrahydrofuran-2-carboxylate has been obtained in 75% yield as a mixture of cis and trans isomers (ratio 64 36). The glycine analog gives both pyrrolidine and piperidine derivatives. ... 

For the examples reported so lar, usually in the presence of die alkene the azomethine ylide is generated in situ by photochemical disrotatory ring-opening of the aziridine (254 nm) in dioxane yielding pyrrolidines. (Obviously, thermal conrotatoiy ring-opening of aziridines demands conditions, which oppose an efficient stereocontrol of the subsequent cycloaddition with a,P-unsaturated carboxylic ester derivatives.)... 

Reactions of chiral azomethine ylides usually derived from imines of a-amino acids have been achieved with electron-deficient alkenes and a, 3-unsaturated carboxylic acid derivatives furnishing pyrrolidines. 

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