GR ID=jo701850un00001><IMG SRC="/isubscribe/journals/joceah/73/i02/figures/jo701850un00001.gif" ALIGN="left" HSPACE=5> |
2,2-Bis-(4-hydroxyphenyl)-cyclopentanone (
3a) was unexpectedly obtained in 76% yield from a reductive couplin
greaction of 4,4'-dihydroxybenzophenone (
1a) and cyclobutanone with TiCl
4 and Zn. Further opt
imization showed thatcatechol as an external li
gand and a hydroxy
group onbenzophenone facilitated the
generation of a quinonemethide(intermediate II) that is involved in the pinacol-type rearran
gement of intermediate I to
give the rearran
ged product.