Ren Shi-Chao, Zhang Feng-Lian, Xu Ai-Qing, Yang Yinuo, Zheng Min, Zhou Xiaoguo, Fu Yao, Wang Yi-Feng
Hefei National Laboratory for Physical Sciences at the Microscale, Center for Excellence in Molecular Synthesis of CAS, Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China.
Department of Chemical Physics, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China.
Nat Commun. 2019 Apr 29;10(1):1934. doi: 10.1038/s41467-019-09825-3.
Organoboron compounds are highly valuable in synthetic chemistry. In particular, α-borylcarbonyl compounds have shown versatile synthetic applications, owing to fruitful chemistries of both the boryl and carbonyl moieties. However, the synthesis of these molecules still remains tedious and time-consuming. Here we report a straightforward and practical route to synthesize α-borylcarbonyl molecules based on a regioselective radical α-borylation of α,β-unsaturated carbonyl compounds. The reaction features unusual α-regioselectivity and high functional-group compatibility. Further synthetic applications of new α-borylated products were also demonstrated. DFT and kinetic studies implicated that the α-regioselectivity of β-aryl-α,β-unsaturated carbonyl compounds was determined by the thermodynamically more favorable radical α-addition step, whereas the formation of α-addition products from β-alkyl-α,β-unsaturated carbonyl compounds was driven by an energetically favored hydrogen atom transfer step. Given that α,β-unsaturated carbonyl compounds can be easily obtained in abundance and variety, this method enjoys great advantages in diverse and economical synthesis of valuable α-borylcarbonyl molecules.
有机硼化合物在合成化学中具有很高的价值。特别是，α-硼羰基化合物由于硼基和羰基部分丰富的化学反应，已显示出广泛的合成应用。然而，这些分子的合成仍然繁琐且耗时。在此，我们报道了一种基于α,β-不饱和羰基化合物的区域选择性自由基α-硼化反应来合成α-硼羰基分子的直接且实用的方法。该反应具有不寻常的α-区域选择性和高官能团兼容性。还展示了新的α-硼化产物的进一步合成应用。密度泛函理论（DFT）和动力学研究表明，β-芳基-α,β-不饱和羰基化合物的α-区域选择性由热力学上更有利的自由基α-加成步骤决定，而β-烷基-α,β-不饱和羰基化合物的α-加成产物的形成则由能量上有利的氢原子转移步骤驱动。鉴于α,β-不饱和羰基化合物可以很容易地大量且多样地获得，这种方法在有价值的α-硼羰基分子的多样化和经济合成中具有很大优势。
