Cobalt-Catalyzed Enantioselective and Chemodivergent Addition of Cyclopropanols to Oxabicyclic Alkenes

We
report herein cobalt-catalyzed enantioselective and chemodivergent
reactions between a cyclopropanol and an oxabicyclic alkene via a
cobalt homoenolate, which afford either an alkylative ring-opening
product or a hydroalkylation product, with the counterion of the cobalt
catalyst being a major chemoselectivity-controlling factor. A catalyst
generated from cobalt­(II) chloride and a chiral diphosphine promotes
alkylative ring opening to afford 1,2-dihydronaphthalen-1-ol derivatives
in good yields with high enantioselectivity. By contrast, a catalyst
generated from cobalt­(II) acetate and the same diphosphine ligand,
with the assistance of methanol, selectively affords hydroalkylation
products with retention of the bicyclic structure at a comparable
level of enantioselectivity.