precaution to avoid the presence of air. Bis(pinacolato)diboron was used to afford β-hydroborated products in the presence of methanol. Adding instead another electrophile allowed the formation of tetrasubstituted vinylboronate species. Finally, the α-products were obtained using pinacolborane as the boron source. All compounds were obtained in high yield with excellent regioselectivity at low catalyst loading
提出了第一种“在空气中”
铜催化的方法,用于选择性合成三和四取代的
乙烯基硼酸酯衍
生物。使用单个催化剂描述了内部
炔烃的
硼化的三种不同变体(α-氢
硼化,β-氢
硼化和碳
硼化):[Cu(Cl)(IMes)](IMes = N,N′-双-[2,4,6-(三甲基)苯基]
咪唑-2-亚烷基)无需采取任何预防措施避免空气的存在。在
甲醇存在下,使用双(
频哪醇)二
硼来提供β-
硼氢化产物。相反,添加另一种亲电试剂可以形成四取代的
乙烯基硼酸酯物质。最后,使用频哪
硼烷作为
硼源获得α产物。所有化合物均以高产率获得,在低催化剂负载量(0.04–2 mol%)下具有出色的区域选择性。该协议构成了访问这些高价值分子的非常便捷的途径。