Exclusive Selectivity in the One-Pot Formation of C–C and C–Se Bonds Involving Ni-Catalyzed Alkyne Hydroselenation: Optimization of the Synthetic Procedure and a Mechanistic Study

A unique
Ni-catalyzed transformation is reported for the one-pot
highly selective synthesis of previously unknown monoseleno-substituted
1,3-dienes starting from easily available terminal alkynes and benzeneselenol.
The combination of a readily available catalyst precursor, Ni­(acac)2, and an appropriately tuned phosphine ligand, PPh2Cy, resulted in the exclusive assembly of the s-gauche diene skeleton via the selective formation of C–C and C–Se
bonds. The unusual diene products were stable under regular experimental
conditions, and the products maintained the s-gauche geometry both in the solid state and in solution, as confirmed by
X-ray analysis and NMR spectroscopy. Thorough mechanistic studies
using ESI-MS revealed the key Ni-containing species involved in the
reaction.

本研究报道了一种独特的镍催化转化策略，可由易得的端炔与苯硒酚出发，通过一锅法高选择性合成此前尚未见报道的单硒取代1,3-二烯烃。该体系采用商业化易得的催化剂前体乙酰丙酮合镍(II) (Ni(acac)₂) 与经适当调优的膦配体苯基二环己基膦 (PPh₂Cy) 组合，可通过选择性构建C–C与C–Se键，专一地得到顺扭（s-gauche）型二烯烃骨架。该类非常规二烯烃产物在常规实验条件下稳定性良好，经X射线分析与核磁共振波谱表征证实，其在固态与溶液中均维持了s-gauche构象。本研究通过电喷雾电离质谱（ESI-MS）开展了详尽的机理研究，阐明了反应过程中关键的含镍活性物种。