Reductive (3 + 2) Annulation of Benzils with Pyrylium Salts: Stereoselective Access to Furyl Analogues of <i>cis</i>-Chalcones
作者:Pengwei Tan、Sunewang R. Wang
DOI:10.1021/acs.orglett.9b02182
日期:2019.8.2
An unprecedented reductive (3 + 2) annulation of both symmetrical and unsymmetrical benzils with pyryliumsalts mediated by P(NMe2)3 is described, leading to facile and stereoselective access to the challenging cis-chalcones decorated by various substituted furyl rings under mild conditions. Rather than the extensively studied C1 synthons, the Kukhtin–Ramirez adducts derived from benzils serve as the
2,2′,6,6′-tetraaryl 4,4′-bipyrannylidenes with eight flexible chains are synthesized by electrochemical reduction of the corresponding 2,6-diarylpyrylium salts.