SYNTHESIS OF A DIMERIC PYRANONAPHTHOQUINONE VIA A NOVEL DOUBLE FUROFURAN ANNULATION STRATEGY

The first synthesis of a dimeric pyranonaphthoquinone 16 which is rela ted to the naturally occurring dimeric pyranonaphthoquinones, e.g. act inorhodin 1 and crisamycin 3, is described. The key biaryl 8 is prepar ed by means of a Suzuki coupling reaction, utilizing the Miyaura reage nt to generate the organoboron coupling partner. The first example of a double annulation of a bisquinone with 2-trimethylsilyloxyfuran to a fford a bisfuronaphthofuran and subsequent double oxidative rearrangem ent to a dimeric pyranonaphthoquinone is described. (C) 1998 Elsevier Science Ltd. All rights reserved.