Zhuo Qingde, Yang Jimin, Zhou Xiaoxi, Shima Takanori, Luo Yi, Hou Zhaomin
Organometallic Chemistry Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako 351-0198, Saitama, Japan.
State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China.
J Am Chem Soc. 2023 Oct 18;145(41):22803-22813. doi: 10.1021/jacs.3c08715. Epub 2023 Oct 5.
The direct use of dinitrogen (N) as a building block for the synthesis of NN-containing organic compounds is of fundamental interest and practical importance but has remained a formidable challenge to date. Here, we report an unprecedented 1,4-conjugate (aza-Michael) addition of N to α,β-unsaturated carbonyl compounds in a dititanium framework. The resulting hydrazinopropenolate products could be easily converted to diverse NN-containing organic compounds such as β-hydrazine-functionalized esters and amides, pyrazolidinones, and pyrazolines depending on the types of Michael acceptors through protonation with MeOH. Further transformations of a hydrazinopropenolate titanium complex through C-C and N-C bond formations with electrophiles such as CO and benzaldehyde have also been achieved. The mechanistic details of the N addition reaction have been elucidated by computational studies, revealing the importance of redox-active metal centers in this event. This work showcases the potential of using N as a building block for the synthesis of NN-containing organic compounds through activation and functionalization in a molecular metal framework.
将二氮（N）直接用作合成含氮有机化合物的原料具有重要的基础研究意义和实际应用价值，但迄今为止仍是一项艰巨的挑战。在此，我们报道了在双钛框架中，氮对α,β-不饱和羰基化合物进行前所未有的1,4-共轭（氮杂迈克尔）加成反应。根据迈克尔受体的类型，通过用甲醇质子化，所得的肼基丙烯酸酯产物可轻松转化为多种含氮有机化合物，如β-肼基官能化的酯和酰胺、吡唑烷酮和吡唑啉。通过与亲电试剂如一氧化碳和苯甲醛形成碳-碳键和氮-碳键，还实现了肼基丙烯酸酯钛配合物的进一步转化。计算研究阐明了氮加成反应的机理细节，揭示了氧化还原活性金属中心在此过程中的重要性。这项工作展示了通过分子金属框架中的活化和官能化，利用氮作为合成含氮有机化合物原料的潜力。
