Transition Metal Cation Salts in Organic Synthesis

Reaction of lithium diisopropylamide (LDA) with (η⁴‐1,3‐cyclohexadiene)Fe(CO)₃ complexes bearing functionalized side chains at C‐5, under an atmosphere of carbon monoxide, gives bridged bicyclo[3,2,1]octene and bicyclo[3,3,1]nonene systems after electrophilic quenching. Under the same reaction conditions, intramolecular cyclization of acyclic (η⁴‐ 1,3‐butadiene)Fe(CO)₃ complexes with functionalized side chains at the terminal position of the diene ligands furnishes fused bicyclo[3.3,0]octanone and bicyclo[4.3.0]nonanone derivatives after acid quenching. The addition of a variety of the highly functionalized zinc‐copper reagents RCu(CN)ZnI to the (η⁷‐cycloheptatrienyl)Cr(CO) gives (η⁶‐cyclohepta‐1,3,5‐triene)Cr(CO)₃ complexes with a functionalized side‐chain at the C‐7 position of the ring. Intramolecular cyclization of ester‐subsbtuted adducts using lithium diisopropylamide generates fused bicyclo[5.3.0]decane and bicyclo[5.4.0]undecane derivatives. The addition of a variety of the highly functionalized zinc‐copper reagents RCu(CN)Znl to the (η⁴‐cyclohexa‐1,3‐diene)Mo(CO)₂(Cp) at the terminus of the coordinated diene ligand gives [Mo(π‐allyl)(CO)₂(Cp)](Cp = cyclopentadienyl) complexes with the functionalized side‐chain at the C‐4 position of the ring. Intramolecular cyclization of the (π‐allyl)molybdenum complex containing a pendant propanoic acid unit generates the δ‐lactone derivative.