Fluorous Dimethyl Sulfide:  A Convenient, Odorless, Recyclable Borane Carrier

Borane gas and 2-(perfluorooctyl)ethyl methyl sulfide form a solid comprised of an approximately 1:1 mixture (fluorous BMS) of sulfide and the corresponding sulfide-borane. Fluorous BMS permits hydroboration of alkenes in a dichloromethane/perfluorinated hydrocarbon mixture with subsequent recycling of the fluorous sulfide by fluorous extraction. The use of fluorous BMS in the asymmetric reduction of ketones catalyzed by a chiral oxaborolidine catalyst, and in the reduction of other functional groups, is also reported.