A new route to the rigidified cyclic β-amino acids such as cispentacin has been developed by sulfanyl radical addition-cyclization of the alkenyl-tethered-oxime ethers and hydrazones.
Radical cyclization in heterocycle synthesis. Part 13: Sulfanyl radical addition–cyclization of oxime ethers and hydrazones connected with alkenes for synthesis of cyclic β-amino acids
combination of sulfanyl radical addition–cyclization of the oximeethers and hydrazones connected with alkenes and subsequent conversion of a phenylsulfanylmethyl group to a carboxyl group provides a novel method for the construction of the cyclic β-amino acids. Upon treatment with thiophenol in the presence of AIBN, the oximeethers and hydrazones smoothly underwent sulfanyl radical addition-cyclization