Oxidative addition/decarbonylation of α,ω-alkanedioyl dichlorides. Metallacycle formation via intramolecular reductive cyclization of a pendant acid chloride with samarium(II) iodide

Controlled oxidative addition and decarbonylation at one end of {alpha},{omega}-alkanedioyl dichlorides is reported with (Ph{sub 3}P){sub 2}Ir(N{sub 2})Cl, giving Ir(III) alkyl complexes bearing a pendant acid chloride functionality. The use of the dinitrogen complex enables suppression of competitive intramolecular lactonization processes. Use of 2 equiv of samarium(II) diiodide uniquely promotes intramolecular reductive cyclometalation of one of these complexes, forming a cyclic acyl complex. This cyclization is highly sensitive to both electronic factors in the substrate and the nature and stoichiometry of the reducing agent.