用配体调控策略, 通过钯催化发展了乙烯基环状碳酰胺和异氰酸酯之间的两类差异性转化, 选择性地合成了多取代的共轭二烯脲类化合物和四氢嘧啶酮衍生物. 当反应以Pd₂(dba)₃•CHCl₃ (dba: dibenzylideneacetone)为催化剂前体、以单齿配位的N,N-二甲基亚磷酰胺(MonoPhos)为配体时, 可以高选择性地得到一系列线性的共轭二烯脲类衍生物; 将配体改为双齿配位的1,3-双(二苯基膦)丙烷(DPPP)时, 利用相同的原料则能够合成一系列环状的四氢嘧啶酮类化合物. 这一研究通过简便的配体调控策略, 为含氮化合物的多样性合成提供了新方法.

Synthesis of urea compounds is highly significant for pharmaceutical chemistry, agricultural chemistry, matterials science and organic synthesis. By ultilizing ligands to switch the chemoselectivity, two transformations of vinyl cyclic carbamates and isocyanates were developed to afford linear and cyclic ureas in a controlled manner. When phosphoramidite was used as the monodentate P-ligand, a wide range of (E)-1,3-diene-substituted linear ureas were produced in high yields and selectivity (21 examples, 51%~95% yields). While, using bidentate biphosphine ligand to replace the phosphoramidite ligand, a variety of highly functionalized vinyl-substitued cyclic ureas, tetrahydro-2-pyrimidinones, were delivered instead starting from the same chemical feedstocks (8 examples, 72%~94% yields). To illusrate the switched chemoselectivity, two possible reaction mechanisms were proposed based on the experiment results and proceeding literatures. The keys of these two reactions, dienylation and annulation, are the β-hydride elimination and the N-allylic alkylation of ally-Pd species, respectively. It is supposed that the basicity of the ligand will affect the reactivity of π-ally-Pd intermediates toward electrophilic ring closing. It is believed that this research not only enriches the application of vinyl carbamate reagents in organic synthesis, but also provides a new protocol to access significant nitrogen-containing molecules.