Masaru Maekawa

Tin-free radical addition of acyloxymethyl to imines.

Acyloxymethyl radicals were generated from the corresponding iodomethyl esters and successfully underwent addition to the CN bond of N-Ts, N-PMP, and N-Dpp imines by the action of dimethylzinc or triethylborane. Ethyl acetate, toluene, and benzene as well as dichloromethane were suitable solvents. The utility of acyloxymethyl radicals as a hydroxymethyl anion equivalent was highlighted by the facile hydrolysis of the acyloxy moiety of the adducts to give the corresponding amino alcohol derivatives in good to high yield.

Chemoselective conjugate addition of dimethylzinc-mediated ether and acetal radicals to alkylidenemalonates and asymmetric reactions.

Cyclic and acyclic ether or acetal radicals were generated directly from ethers or acetals by the action of dimethylzinc-air, and their subsequent conjugate addition reaction with alkylidenemalonates afforded the corresponding conjugate adducts in reasonably high yields. The reaction with benzylidenemalonates bearing formyl and imino groups gave chemoselectively the conjugate addition products. The asymmetric reaction of bis(8-phenylmenthyl) benzylidenemalonate proceeded diastereoselectively to provide the adduct with 93:7 dr.