| 研究実績の概要 |
The initial synthetic plan was the construction of the cage structure by sequential silyl protection, Ullmann coupling, and phosphination. However, the experimental result suggested direct silyl protection of 2-iodophenol was a challenge. Hence, MOMCl was used to protect iodophenol, Ullmann coupling between the protected product and methyl amine delivered the aniline in 37% yield. However, the reaction with PCl3 resulted in a complex mixture, which was thought to be due to in situ deprotection of MOM and the sluggish reactivity with PCl3.
On the other hand, I previously developed a Ni-catalyzed defluorophosphonylation reaction between aryl fluorides and H-phosphonates to produce the corresponding aryl phosphonates . A wide range of aryl fluorides, including electron-rich and electron-neutral ones, were functionalized without the requirement of pre-activation. However, the mechanistic insight, especially the role of phosphorus reagents, was remained unresolved. The target of this project was to reveal the unknown behaviors of phosphorus reagents in catalysis by using computational methods. Mechanistic studies based on both experimental and computational investigations suggested in situ generated KOP(OR)2 could reduce Ni(II) complex to Ni(0) species. Next, dissociation of KOP(OR)2 and association of aryl fluorides generate catalytic species, in which the phosphite forms a strong electron-donating dimeric ligand system for performing C-F oxidative addition in a low energy barrier.
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