Nm. Kablaoui et al., TITANOCENE-CATALYZED CYCLOCARBONYLATION OF O-ALLYL ARYL KETONES TO GAMMA-BUTYROLACTONES, Journal of the American Chemical Society, 119(19), 1997, pp. 4424-4431
A method for the transformation of o-allyl aryl ketones to gamma-butyr
olactones using a catalytic amount of Cp2Ti(PMe3)(2) or Cp2Ti(CO)(2) i
s described. This catalytic ''hetero Pauson-Khand''-type process proce
eds via the carbonylation of an oxatitanacycle followed by thermally-i
nduced reductive elimination to form a gamma-butyrolactone and to rege
nerate the catalyst. We have investigated the scope and limitations of
this catalytic methodology. Our results are consistent with the view
that the key step in this catalytic cycle is formation of a charge tra
nsfer complex or involves reversible electron transfer between the cat
alyst and the substrate.