Browsing by Author "Liu, Xiaocui"

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    Regio- and Stereoselective Synthesis of 1,1-Diborylalkenes via Bronsted Base-Catalyzed Mixed Diboration of Alkynyl Esters and Amides with BpinBdan
    Liu, Xiaocui; Ming, Wenbo; Luo, Xiaoling; Friedrich, Alexandra; Maier, Jan; Radius, Udo; Santos, Webster L.; Marder, Todd B. (2020-04)
    The NaOtBu-catalyzed mixed 1,1-diboration of terminal alkynes using the unsymmetrical diboron reagent BpinBdan (pin = pinacolato; dan = 1,8-diaminonaphthalene) proceeds in a regio- and stereoselective fashion affording moderate to high yields of 1,1-diborylalkenes bearing orthogonal boron protecting groups. It is applicable to gram-scale synthesis without loss of yield or selectivity. The mixed 1,1-diborylalkene products can be utilized in Suzuki-Miyaura cross-coupling reactions which take place selectivly at the C-B site. DFT calculations suggest the NaOtBu-catalyzed mixed 1,1-diboration of alkynes occurs through deprotonation of the terminal alkyne, stepwise addition of BpinBdan to the terminal carbon followed by protonation with tBuOH. Experimentally observed selective formation of (Z)-diborylalkenes is supported by our theoretical studies.