Friedel-Crafts acylation of W(CO)5-complexes of azaferrocenes

Blocking of the lone pair of electrons on the nitrogen atom in azaferrocene by coordination to the W(CO)5 moiety (as in complexes 1a-b) enables Friedel-Crafts acylation of this metallocene. The reaction occurs selectively at the cyclopentadienyl ligand in 10-50% yield. The X-ray structure of 2a was determined.