Thioureas as Highly Active Catalysts for Biomimetic Bromocyclization of Geranyl Derivatives.

Thioureas bearing electron-deficient aryl groups show high catalytic activity in the biomimetic bromocyclization of geranyl derivatives. The reaction of geranyl derivatives with N-bromosuccinimide (NBS) proceeds rapidly in CHCl to give the corresponding bromocyclization products in high yields as a ca. 1:1 mixture of endo- and exo-isomers.