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Free keywords:
alkynes; hydroboration; pinacolboronates; ruthenium; trans addition
Abstract:
Violate the rule: The reigning stereochemical principle of hydroboration is the suprafacial delivery of hydrogen and boron to the same π-face of a given starting material. This fundamental rule of cis addition is now easily broken for internal alkynes with the help of [Cp*Ru(MeCN)3]PF6 (Cp*=η5-C5Me5) as the catalyst. The resulting trans-selective hydroboration opens a practical new entry into E-configured alkenylboron derivatives.