Development of Methods for Novel Construction of Ring Compounds by Environmentally Benign Transition Metal Catalysts

创造新型的过渡金属配合物，表现出高的催化性能是非常重要的发展高度原子经济和环境友好的合成方法。在本研究中，我们首次成功地通过选择性取代Ru（η^6- 1，3，5-环辛三烯）（η^2-富马酸二甲酯）_2（1）中的1，3，5-环辛三烯（cot）或富马酸二甲酯（dmfm）配体，制备了含芳烃、对苯醌、吡啶基三齿配体和马来酰亚胺的新型Ru（0）配合物。与之形成鲜明对比的是，类似的Ru（0）络合物Ru（η^4- 1，5-环辛二烯）（η^6- 1，3，5-环辛三烯）（2）与顺丁烯二酰亚胺反应，通过cot配体与顺丁烯二酰亚胺在钌催化剂上的氧化环化反应，顺利地合成了新型的二价双烯并环戊烷配合物（3），这可能实现新型过渡金属催化的[6+2]共环化反应的发展。基于上述化学计量反应，本研究开发了使用环境友好的钌和铑催化剂构建各种环化合物的新方法。代表性实例包括1）异氰酸酯、炔和一氧化碳的第一次铑催化的[2+2+1]共环化能够快速合成多取代的马来酰亚胺，2）通过控制异氰酸酯和炔的摩尔比，铑催化的异氰酸酯和炔的环共三聚导致选择性形成2-吡啶酮和嘧啶-2，4-二酮，3）铑催化的由环丁烯酮和缺电子烯烃通过C-C键断裂/脱氢直接合成取代苯酚，和4）不同烯烃的选择性共二聚和共三聚，以及乙烯的选择性三聚，通过双烯环中间体。所有反应都以高原子效率进行，并在不形成副产物的情况下得到官能单体。

The creation of novel transition metal complexes which show high catalytic performance is essential for development of highly atom-economical and environmentally benign synthetic methods. In this study, we first succeeded in preparation of novel Ru (0) complexes bearing arenes, p-quinones, tridentate pyridyl ligands, and maleimides via selective displacement of either1,3,5-cyclooctatriene (cot) or dimethyl fumarate (dmfm) ligands in Ru (η^6-1,3,5-cyclooctatriene) (η^2-dimethyl fumarate)_2 (1). In sharp contrast, a similar Ru (0) complex, Ru (η^4-1,5-cyclooctadiene) (η^6-1,3,5-cyclooctatriene) (2) smoothly reacted with maleimides to give novel divalent ruthenacyclopentane complexes (3) via oxidative cyclization of a cot ligand and maleimides on the ruthenium, which may realize the development of novel transition-metal catalyzed [6+2] cocyclization reaction.Based on the above described stoichiometric reactions, novel methods for construction of various ring compounds using environmentally benign ruthenium and rhodium catalysts have been developed in this study. Representative examples include 1) first ruthenium-catalyzed [2+2+1] cocyclization of isocyanates, alkynes, and carbon monoxide enables the rapid synthesis of polysubstituted maleimides, 2) rhodium-catalyzed cyclocotrimerization of isocyanates and alkynes leading to the selective formation of 2-pyridones and pyrimicline-2,4-diones by controlling the molar ratio of isocyanates and alkynes, 3) rhodium-catalyzed direct synthesis of substituted phenols from cyclobutenones and electron-deficient alkenes via C-C bond cleavage/dehydrogenation, and 4) selective codimerization and cotrimerization of different alkenes, as well as selective trimerization of ethylene, via ruthenacyclic intermediates. All reactions proceed with high atom-efficiency and give functional monomers without the formation of byproducts.