Effective Acceleration of Atom Transfer Carbonylation of Alkyl Iodides by Metal Complexes. Application to the Synthesis of the Hinokinin Precursor and Dihydrocapsaicin
[reaction: see text] Atom transfer carbonylation (ATC) of alkyl iodides leading to carboxylic acid esters is effectively accelerated by Pd(PPh(3))(4) and Mn(2)(CO)(10) under photoirradiation conditions. In the presence of amines, Pd(0) complexes affected double carbonylations leading to alpha-keto amides, whereas Mn(2)(CO)(10) accelerated only a single carbonylation reaction leading to the corresponding
[GRAPHICS]Five- to seven-membered lactones were prepared from omega-hydroxyalkyl iodides and CO by atom transfer carbonylation without the need for transition metal catalysts, The reaction proceeds via a hybrid radical/ionic mechanism in which the intramolecular alcoholysis of an omega-hydroxyacyl iodide, arising from atom transfer carbonylation, leads to the lactone.