Four Ru(II)-NC complexes were tested as catalysts for semihydrogenation of internal alkynes to (E)-alkenes with ethanol, and the complex {(C₅H₄N)(C₆H₄)}RuCl(CO)(PPh₃)₂ (1a) showed the highest activity. The reactions proceeded well with 1 mol % catalyst loading and 0.1 equiv of t-BuONa at 110 °C for 1 h, and 32 alkenes were synthesized with excellent E:Z selectivity. This is the first ruthenium-catalyzed semihydrogenation of internal alkynes to (E)-alkenes using ethanol as the hydrogen donor.

中文翻译：

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双齿Ru（II）-NC配合物，用乙醇将炔烃半氢化为（E）-烯烃的催化剂

测试了四种Ru（II）-NC配合物作为催化剂，用乙醇将内部炔烃半氢化为（E）-烯烃，以及配合物{（C ₅ H ₄ N）（C ₆ H ₄）} RuCl（CO）（PPh ₃）₂（1a）显示最高活性。反应在110℃下以1 mol％的催化剂负载量和0.1当量的t- BuONa进行了1小时，反应良好，合成了32种烯烃，具有出色的E：Z选择性。这是第一次使用乙醇作为氢供体的钌催化的内部炔烃半氢化为（E）-烯烃。