Directed synthesis of phosphorus-substituted cyclopentadienones and cyclobutadienes via metal carbonyl promoted coupling of acetylenes held proximate to a metal

Article abstract of DOI:10.1021/om00088a023

A strategy for the synthesis of heteroatom-substituted cyclobutadienes and cyclopentadienones via metal carbonyl promoted coupling of acetylenes held proximate via cis coordination to square-planar Pt(II) is outlined. Reaction of cis-Cl₂Pt(Ph₂PC≡C-t-Bu)₂ with Fe₂(CO)₉ gives good yields of the η⁴-cyclobutadiene complex Cl₂Pt[(Ph₂P)₂C₄-t-Bu ₂]Fe(CO)₃ (II) which has been characterized by X-ray diffraction. Treatment of cis-X₂Pt(Ph₂PC≡CR)₂ (I, X = Cl, Br, I, Ph, 2-Me-C₆H₄, CF₃, C₆F₅; 2X = 1,2-C₆H₄O₂; R = Ph, Cy, SiMe₃) with Fe₂(CO)₉ generates cyclopentadienone derivatives IV (e.g., Cl₂Pt-[(Ph₂P)₂C₄Ph ₂CO]Fe(CO)₃) and/or V (e.g., (C₆F₅)₂Pt-[(Ph₂P)₂C ₄Ph₂CO]), examples of which have been characterized by X-ray analysis.