[1,3]-Claisen Rearrangement via Removable Functional Group Mediated Radical Stabilization

A thermal O-to-C [1,3]-rearrangement
of α-hydroxy acid derived
enol ethers was achieved under mild conditions. The 2-aminothiophenol
protection of carboxylic acids facilitates formation of the [1,3]
precursor and its thermal rearrangement via stabilization of a radical
intermediate. Experimental and theoretical evidence for dissociative
radical pair formation, its captodative stability via aminothiophenol,
and a unique solvent effect are presented. The aminothiophenol was
deprotected from rearrangement products as well as after derivatization
to useful synthons.