ADDITION OF SILYLOXYDIENES TO 2-SUBSTITUTED 1,4-BENZOQUINONES AND 1,4-NAPHTHOQUINONES

Addition of 1-trimethylsilyloxybuta-1,3-diene 2 to the quinones 4,5,6, 17,18,19,20 bearing formyl, acetyl, methoxycarbonyl or carboxamide sub stituents at C-2, afforded the Diels-Alder adducts 11,12,13,25,26,27,2 8 whereas addition of 2-trimethylsilyloxyfuran 3 afforded the fragment ation products 29,30,31,35,36,37,38. Quinones 7,21 bearing a carboxyl group at C-2 afforded 1,4-naphthoquinone and 9,10-anthracenedione with 2 and no adducts were isolated from reaction with 3. Benzoquinone-sul fide 8 afforded Diels-Alder adduct 14 and fragmentation product 32 wit h 2 and 3 respectively whereby reaction occurred on the less substitut ed double bond. No adducts were isolated upon treatment of naphthoquin one-sulfide 22 with either 2 or 3. The Diels-Alder adducts of benzoqui none-sulfoxide 9 and naphthoquinone-sulfoxide 23 with 2 underwent faci le aromatisation to 1,4-naphthoquinone and 9,10-anthracenedione with 2 . Addition of 3 to 9 afforded fragmentation product 33 whereas analogo us reaction with 23 was unsuccessful. Addition of dienes 2,3 to benzoq uinone-sulfone 10 afforded fragmentation products 16,34 respectively, whereas naphthoquinone-sulfone 24 afforded 9,10-anthracendione with 2 and no products with 3. (C) 1997 Elsevier Science Ltd.