Radical Coupling of Iodocarbonyl Compounds with Butenylindium Generated by Transmetalation between Cyclopropylmethylstannane and Indium Halides

The reaction of cyclopropylmethylstannane 1 with α-iodocarbonyl compounds 2 in the presence of either InBr3 or InCl3 gave the C−C coupling products 3. Various types of iodocarbonyl compounds such as esters, amides, and ketones were applied to this system to afford the corresponding cyclopropylethyl-substituted carbonyls 3. Transmetalation between cyclopropylmethylstannane and indium halides afforded butenylindium dihalide and dibutenylindium halide, as confirmed by NMR spectroscopy. The reactivity of dibutenylindium halide was greater than that of monobutenyl species. The active species, dibutenylindium halide, was stabilized by complexation using DPPE, and its structure was analyzed using X-ray crystallography. The solid state of the complex shows a linear structure with a core (−Cl−In−Cl–In–P−C−C−P−In−)n with five-coordinated indium centers. The reaction between 1 and 2, mediated by indium halides, proceeded in a radical manner. The in situ-generated alkylindium species and a small amount of oxygen, which can be supplied by atmospheric air, initiated the radical reaction.