In a preliminary screening for reactivity, we chose 1-alkynyltriisopropylboronates as the alkynylating agents. These compounds are readily available from the corresponding terminal alkynes, 7 and they have rarely been used in an asymmetric addition to activated alkenes. 8 A number of rhodium sources, solvents and phosphorus-containing chiral ligands were evaluated as catalysts in the reaction. While THF, dichloromethane and toluene proved to be ineffective solvents, the ...
