Rhodium-catalysed asymmetric ring opening reactions with carboxylate nucleophiles

We have developed an asymmetric ring opening reaction of oxabenzonorbornadiene with carboxylate nucleophiles to generate enantiomerically enriched hydronaphthalene products containing an allylic carboxylate moiety. These reactions occur in good yield and excellent enantioselectivity (>90% ee). The allylic carboxylate functionality was found to be stable towards reaction with the rhodium catalyst under the reaction conditions. In order to obtain these results, two advancements were required. First, the use of protic additives was necessary for good reactivity. Second, the exchange of the halide Ligand on the catalyst from chloride to iodide was required to obtain high ee. (C) 2001 Elsevier Science Ltd. All rights reserved.