Cascade Palladium-Catalyzed Direct Intramolecular Arylation/Alkene Isomerization Sequences: Synthesis of Indoles and Benzofurans
作者:Myriam Yagoubi、Ana C. F. Cruz、Paula L. Nichols、Richard L. Elliott、Michael C. Willis
DOI:10.1002/anie.201004097
日期:2010.10.18
One route, two cycles: A palladium‐catalyzed intramoleculardirectarylation reaction combined with an isomerization step provided a straightforward synthetic route to both indoles and benzofurans (see scheme). Isolation and functionalization of intermediate alkene isomers allowed the formation of variants having substituents remote from the core.
An efficient and facile method for the synthesis of a broad series of benzofurans and naphthofurans is described. The direct intramolecular cyclodehydration of aryloxyketones in the presence of titaniumtetrachloride affords the corresponding benzofurans and naphthofurans with good regioselectivity and yields.
Reported here is the direct synthesis of naphthofurans and benzofurans from readily available phenols and α-haloketones promoted by titanium tetrachloride which combines Friedel–Crafts-like alkylation and intramolecular cyclodehydration into one step. This simple protocol allows for the formation of a variety of high value naphthofurans and benzofurans within which a series of cyclic and acyclic groups