Transition‐Metal‐Catalyzed Carbonylative Domino Reactions

Abstract

‘‘Sustainable development’’ has become one of the hottest terms in the twenty-first century. Of particular relevance in organic chemistry are the reaction efficiency and the avoidance of waste generation. With regard to sustainability, methodologies based on domino reactions, including multicomponent reactions, are a highly efficient strategy to synthesize complicated organic compounds. Domino reactions are defined as processes of two or more bond-forming reactions under identical conditions, in which the subsequent transformations take place at the functionalities that are obtained in the previous bond-forming transformations. Using domino reactions, complicated compounds can be relatively easily prepared from simple substrates. No tedious preparation of intermediates and purification processes are needed, which are the most energy-consuming and waste-generating steps in organic synthesis [1]. One prominent example is the domino Knoevenagel/hetero-Diels–Alder reaction, in which dihydropyrans could be straightforwardly synthesized from readily available starting materials [2]. Transition-metal catalysts play an ever-increasing and important role in modern chemistry [3]. Numerous transition-metal-catalyzed coupling reactions have been developed and applied in the total synthesis of natural products, such as the Suzuki reaction, theNegishi reaction, theHeck reaction, andmany others [4]. Interestingly, the power of transition-metal catalysts is even more visible in the area of domino reactions, where terms such as palladium walking show the value of transition metals in bond formations. Carbonylation reactions are interesting and important with regard to both industrial and academic research [5]. In these reactions, carbonmonoxide (CO) can be used as one of the cheapest C1 sources. By introducing one or even more CO units into the parent molecules, carbonyl-containing products are easily prepared, which can be further modified to yield important chemicals for organic synthesis. Following the definition of domino reactions, we realized to our surprise that all the carbonylative coupling reactions belong to domino reactions, in which at least two C–C bonds were formed under the same reaction conditions.