Abstract
The metal-η 3 -2-methoxycarbonylpentadienyl complexes (C 5 R 5 )M(CO) 2 (syn-Ti 3 -2-COOMe-C 6 H 5 )(R=H, M=W; R=H, Me, M= Mo) undergo a novel acid-catalysed cotrimerization with a- and (3-unsaturated ketones to afford two products with diastereoisomeric six-membered rings which have been structurally characterized by X-ray diffraction.