Radical cyclization in heterocycle synthesis. 6. A new entry to cyclic amino alcohols via stannyl radical cyclization of oxime ethers connected with aldehydes or ketones

Grime ethers connected by a tether to aldehydes or ketones efficiently cyclize via stannyl radical addition-cyclization to provide a new entry to cyclic amino alcohols. Upon treatment with tributyltin hydride in the presence of AIBN, oxime ethers connected with either an aldehyde or a ketone via a nitrogen atom smoothly underwent stannyl radical addition-cyclization to give five- to seven-membered cis- and trans-heterocyclic amino alcohols of which the trans-isomers were major products. The newly found radical cyclization provides a novel method for preparing not only bifunctionalized heterocyclic compounds but also adjacently functionalized amino alcohols carrying two quaternary carbons.