A method is described for carrying out indium-mediatedallylation reactions of phenacyl bromides in aqueous solution that form homoallylic bromohydrins. By employing subsequent base treatment, the homoallylic bromohydrins were converted to allylic epoxides. Finally, the process has been used as a key step in a concise sequence for the synthesis of 3-allylbenzofuran.
Simple Synthetic Method of Allyl- and Vinyl-Epoxides by Allylation of Carbonyl Groups with Allylic Tins Catalyzed by PbI<sub>2</sub>-HMPA
作者:Ikuya Shibata、Shoji Fukuoka、Akio Baba
DOI:10.1246/cl.1998.533
日期:1998.6
the chemoseletive allylation at the carbonyl groups of α-bromo ketones with allylic tin, where PbI2-HMPA effected as a chemoselective catalyst. Moreover, vinyl epoxides were obtained in one pot procedure by the PbI2-HMPA catalyzed reaction of γ-chloroallyltri-n-butyltin with aldehydes. Because of the mildness of the catalyst, the formed epoxide functionalities were not decomposed.
The cyclization reaction of diallyldibutyltin and α- or γ-halo ketones, especially chloro-substituted ketones, effectively proceeds in the presence of a catalytic amount of tetraethylammonium chloride, producing the corresponding 2-allyloxiranes or 2-allyltetrahydrofurans in high yield, respectively. β-Chloro ketones give the corresponding allyl alcohols.