1,4-Dipole-metalated quinone strategy to (.+-.)-4-demethoxydaunomycinone and (.+-.)-daunomycinone. Annelation of benzocyclobutenedione monoketals with lithioquinone bisketals
1,4-Dipole-metalated quinone strategy to (.+-.)-4-demethoxydaunomycinone and (.+-.)-daunomycinone. Annelation of benzocyclobutenedione monoketals with lithioquinone bisketals