Iodoimide, atom transfer addition

Fhal and Renaud have examined the alkylation of a radical generated from the a-iodoimide 333 with a variety of Lewis acids, as shown in Sch. 42 [70]. The stereogenic step in this process would be hydrogen atom transfer from tin to a Lewis acid-com-plexed radical generated from 333. Initial screening was performed for the reaction of allyltributylstannane and imide 333, which was conducted by precomplexation of the imide with the Lewis acid and then addition of the stannane in the presence of AIBN under irradiation at 10 °C. The Lewis acid prepared from BINOL was ineffective whereas that prepared from the bis-sulfonamide 337 was slightly superior to that from the TADDOL ligand 339. 

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