A method for the transformation of o-allyl aryl ketones to γ-butyrolactones using a catalytic amount of Cp2Ti (PMe3) 2 or Cp2Ti (CO) 2 is described. This catalytic “hetero Pauson- Khand”-type process proceeds via the carbonylation of an oxatitanacycle followed by thermally-induced reductive elimination to form a γ-butyrolactone and to regenerate the catalyst. We have investigated the scope and limitations of this catalytic methodology. Our ...