Asymmetric cyclization via oxygen cation radical: Enantioselective synthesis of cis-4b,9b-dihydrobenzofuro[3,2-b]benzofurans
Aerobic oxidative cyclization of 2,2′-dihydroxystilbenes via oxygen cation radical to give cis-4b,9b-dihydrobenzofuro[3,2-b]benzofurans was carried out in an enantioselective manner (up to 89% ee) by using (nitrosyl)Ru(salen) 10 as the catalyst under phot