Dong Ming, Tong Xiaofeng
School of Materials Science and Engineering, Changzhou University, Changzhou, Jiangsu, 213164, China.
School of Pharmaceutical and Chemical Engineering, Taizhou University, Taizhou, Zhejiang, 318000, China.
Chemistry. 2024 May 2;30(25):e202400236. doi: 10.1002/chem.202400236. Epub 2024 Mar 13.
The insertion of carbonyl into C(sp)-Pd(II) σ-bond (Grignard-type addition) was not established until the 1990s. While this elemental reaction has been well explored since then, its application in Pd(0) asymmetric catalysis remain elusive. Herein, we report the Pd(0)-catalyzed asymmetric intramolecular Grignard-type reaction of vinyl iodide-carbonyl in the presence of HCOH additive, affording cyclic allylic alcohol with good to excellent enantioselectivity and diastereoselectivity. Mechanistic studies suggested that besides serving as an efficient reductant, HCOH is also capable of facilitating protonation of the involved secondary alkoxyl-Pd(II), thus completely suppressing the β-H elimination. Moreover, no KIE was found in the competing reaction between vinyl iodide-aldehyde and 1-deuterated one, demonstrating the facile step of aldehyde insertion.
直到20世纪90年代，羰基插入C(sp)-Pd(II) σ键（格氏型加成）才得以确立。自那时起，虽然这一基本反应已得到充分探索，但其在Pd(0)不对称催化中的应用仍然难以捉摸。在此，我们报道了在HCOH添加剂存在下，Pd(0)催化的乙烯基碘-羰基的不对称分子内格氏型反应，得到具有良好至优异对映选择性和非对映选择性的环状烯丙醇。机理研究表明，HCOH除了作为一种有效的还原剂外，还能够促进相关仲烷氧基-Pd(II)的质子化，从而完全抑制β-H消除。此外，在乙烯基碘-醛与1-氘代乙烯基碘-醛的竞争反应中未发现动力学同位素效应，这表明醛插入步骤较为容易。
