Synthesis of spiropyrrolidines and spiropyrrolizidines by 1,3-dipolar cycloadditions of azomethine ylides to substituted α-methylene-γ-lactones
作者:Jakub Častulı́k、Jaromı́r Marek、Ctibor Mazal
DOI:10.1016/s0040-4020(01)00807-9
日期:2001.9
1,3-Dipolar cycloadditions of (E)- and (Z)-substituted α-methylene-γ-lactones with azomethine ylides derived from N-methyl glycine and l-proline gave the corresponding spiropyrrolidine and spiropyrrolizidine cycloadducts in good to moderate yields with various extent of stereoselectivity and regioselectivity. Cycloadditions of the azomethine ylide derived from l-proline exhibited endo selectivity especially
Stereoselective synthesis of α-alkylidene- and substituted alkylidene-γ-lactones
作者:Jakub Častulı́k、Ctibor Mazal
DOI:10.1016/s0040-4039(00)00252-5
日期:2000.4
Cross-coupling reactions of (E)- and (Z)-tosylates of α-hydroxymethylene-γ-butyrolactone with aryl, heteroaryl, alkyl, and alkynylzinc chlorides under Pd(PPh3)4 catalysis were found to be a suitable synthetic method for stereoselective preparation of α-alkylidene- and substituted alkylidene-γ-lactones. The reactions, conducted under mild conditions, proceed with high stereoselectivity and moderate yields.