SYNTHETIC STUDIES TOWARDS PANACENE (1)
2-Trimethylsilyloxyfuran (l}) and 2-acetyl-1 ,4-benzoquinone
(6) were prepared according to published methods. The uncatalysed addition of 2-trfmethylsilyloxyfuran (23) to
the quinone (6) gave cis-3a,8b-dihydro-8-acetyl-7-hydroxyfuro [3,2-b]benzofuran-2-(3H)-one (24) in 50% yield. The reaction of other 1,4-benzoquinones was investigated, establishing the necessity of an activating substituent at C-2 of the quinone. Attempts to reduce the acetyl group of cis-3a,8b-dihydro-8-
-acetyl-7-hydroxyfuro[3,2-b]benzofuran-2-(3H)-one (24) to the ethyl group present in Panacene (l) were unsuccessful, although reduction of the ketone with sodium borohydride gave
cis-3a,8b-dihydro-8-(1 '-hydroxyethyl)-7-hydroxyfuro[3,2-b] benzofuran-2-(3H)-one (51).
The conversion of cis-3a,8b-dihydro-8-acetyl-7-hydroxyfuro [3,2-b]henzofuran-2-(3H)-one (24) to cis-3,3a,9b-trihydro- 5-hydroxy-5-methylfuro[3,2-c]benzopyran-2,6,9-(5H)-trione (58) was carried out using cerie ammonium nitrate.