Reactivity of organic tin compounds

The kinetics of the R3SnCH2CO2 Et (R=Me, Et, Bu, Ph) reactions with iodine in the presence of KI and R31SnI (R1=Me, Ph) in DMFA is studied. It has been found that at R1=Me the reaction has the first order with respect to organic tin compound and the first order with respect to iodine (R=Et, Bu) or zero order with respect to iodine (R=Ph). The reaction rate in these cases depends on Me3SnI concentration. At R1=Ph the reaction has a total second order, first for each reagent, and its rate is independent of Ph3SnI concentration. It has been found that an exchange between R3SnCH2CO2Et and Me2SnI in DMFA with formation of Me3SnCH2CO2Et and R3SnI occurs and its rate is measured at R=Ph. It is assumed that the reaction occurs with participation of reactive O-tautomer of stannylated ester produced from the R3SnCH2CO2EtxR31SnI complex At R1=Me in the reaction active Me3SnOH2CO2Et is obtained which results in its acceleration