An unusual pathway to cyclobutane formation via desulfurative intramolecular photocycloaddition of an enone benzothiazoline pair.
Irradiation of the enone benzothiazoline 3 leads to the formation of cyclobutane 5. Preliminary mechanistic studies establish the intermediacy of an enecarbamate 14 in this photochemical transformation, which could be the result of sulfur extrusion from an episulfide intermediate. Photocycloaddition of the enecarbamate intermediate 14 leads to the formation of "crossed" photoadducts, i.e., 5, in excellent yield, with high levels of regio- and stereochemical control.
Jo
Hyunil
H
Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Fitzgerald
Mark E
ME
Winkler
Jeffrey D
JD