REGIOSPECIFIC SYNTHESIS OF POLYSUBSTITUTED FURANS FROM SILYLATED FURANS - EXPEDIENT SYNTHESES OF ROSEFURAN

By utilizing a sequence of regiospecific lithiation-alkylation, ipso-i odination, boroxine formation, Sonogashira cross-coupling, nickel-cata lyzed cross-coupling and Suzuki cross-coupling reactions, several meth ods have been developed for the syntheses of 2,3-disubstituted furans, 2,4-disubstituted furans, 2,3,4-trisubstituted furans and 2,3,5-trisu bstituted furans. Our approach uses as the key theme trimethylsilyl gr oups as both blocking groups as well as ipso-directing groups. The adv antage of this program is aptly illustrated by two expedient syntheses of rosefuran (9c). (C) 1997 Elsevier Science Ltd.