Toward understanding the scope of Baylis–Hillman reaction: synthesis of 3-(2- hydroxyphenyl)indolin-2-ones and polycyclic fused furans

A facile one-pot synthesis of 3-(2-hydroxyphenyl)indolin-2-ones has been developed via the TiCl4-mediated Baylis–Hillman (B–H) reaction of N-substituted isatins and cyclohex-2-enone, followed by treatment of the in situ generated B–H alcohols with aq HBr. Baylis–Hillman reaction of aromatic cyclic 1,2-diones with cycloalk-2-enones under the influence of TiCl4 has been successfully performed and the resulting Baylis–Hillman adducts have been conveniently transformed into pentacyclic and hexacyclic fused furan derivatives.