Iron complexes, allenyl cycloaddition reactions

Other variations of the [3 + 2] cycloaddition chemistry involving either SO2 or a S2O equivalent have been explored (Scheme 47). Iron allenyl complexes undergo reaction with SO2 to give either vinyl iron (105) or (106), depending on the substitution pattern. A propargylic iron complex reacts in a similar manner to give (107), but reacts with a cyclic thiosulfinate ester to give (108). 

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