IRON CARBONYL PROMOTED CONVERSION OF ALPHA,OMEGA-DIYNES TO (CYCLOPENTADIENONE)IRON COMPLEXES

An efficient high-yielding procedure is described for the intramolecular carbonylative coupling of alpha,omega-diynes to give cyclopentadienone-Fe(CO)3 complexes. Exchanging one CO ligand with PPh3 affords control over the manipulation of alpha,alpha'-trimethylsilyl-substituted cyclopentadienone complexes. The preparation of alpha,omega-diynes with a hydroxy group adjacent to one alkyne unit leads to modest stereocontrol upon cyclization forming the Fe(CO)3 complex. The hydroxy-substituted complex was oxidized to ketone. Borohydride reduction and Grignard addition to the ketone proceed anti to the Fe(CO)3 moiety. The X-ray crystal structure of C40H31FeO3P shows that it crystallizes in the monoclinic space group P2(1)/n in a unit cell of dimensions a = 12.0595 (24), b = 13.3926 (30), c = 19.0682 (38) angstrom, beta = 93.98 (2)-degrees, with Z = 4.