Radical-chain reactions of sulfonyl azides and of ethyl azidoformate with allylstannanes: Homolytic allylation at nitrogen

4-Methylbenzenesulfonyl azide reacts with allyltriphenylstannane (ATPS) in refluxing benzene, in the presence of 2,2'-azobis(2-methylpropionitrile) as initiator, to give N-allyl-4-methylbenzenesulfonamide in good yield after hydrolytic work-up. Small amounts of allyl 4-methylphenyl sulfone were also formed. The reaction follows a free-radical chain mechanism which involves competitive addition of Ph(3)Sn(.) to Na and to N-c of the azido group in (ArSO2NNNc)-N-a-N-b. Addition to N-a followed by loss of nitrogen gives ArSO(2)NSnPh(3), the precursor of the N-allylarenesulfonamide, while addition to N-c leads to the formation of ArSO2 and thence to the allyl aryl sulfone. Allyltrimethylstannane behaves in a similar way to ATPS, but allyltributylstannane gives only a low yield of N-allylarenesulfonamide and the major product is the unsubstituted sulfonamide MeC(6)H(4)SO(2)NH(2), which results because the radical ArSO(2)SnBu(3) undergoes intramolecular 1,5-hydrogen-atom transfer in preference to adding to the allylstannane. 2-Methylallyltriphenylstannane reacts in an analogous way to ATPS, but allylstannanes containing nonterminal double bonds do not react successfully. The arenesulfonyl azides 4-XC(6)H(4)SO(2)N(3) (X = H, MeO, F) react in a similar way to tosyl azide, but the reaction is very sluggish when X = NO2. With 1-octanesulfonyl azide, reaction with Ph(3)Sn is much less selective and products arising from attack at N-a and N-c are formed in comparable yields. Ethyl azidoformate reacts with allylstannanes in a similar manner to, although more slowly than, tosyl azide and gives good yields of the corresponding allylic carbamates.