Why Does Rh Prefer [4 + 1] while Pd Prefer [4 + 4 + 1] Mode in Carbocyclization of Vinylallene with CO? Unveiling Nickel’s Potential for Expanding the Scope Beyond Pd
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引用次数: 0
Abstract
Rhodium(I) promotes a [4 + 1] assembly mode with a vinylallene substrate and CO, leading to the formation of a five-membered ring structure. In striking contrast, palladium(0) catalyzes a more complex [4 + 4 + 1] mode leading to a nine-membered cyclic ketone. The underlying mechanisms that govern this contrast in assembly modes remain unclear, even in today’s date, presenting a major challenge to the further development of efficient reactions. Our computational study reveals that Rh adopts a square pyramidal geometry with CO. This is in contrast to Pd, which prefers a trigonal planar geometry. A stronger metal–CO interaction is detected in Rh than in a Pd intermediate, making the [4 + 1] mode more preferable in Rh than in Pd. The transition state for C–C coupling between two vinylallene has a significantly distorted tetrahedral core in the case of Rh, while Pd retains a stable trigonal planar structure, making the [4 + 4 + 1] reaction less favorable in Rh than in Pd. By conceptualizing and transferring the critical features of Pd to Ni systems, we have rationally designed a Ni-catalyzed [4 + 4 + 1] version that combines the desirable reactivity of Pd with the cost-effectiveness and abundance of Ni, aligning with the growing demand for more sustainable and atom-efficient strategies in synthetic organic chemistry.
期刊介绍:
Journal of Organic Chemistry welcomes original contributions of fundamental research in all branches of the theory and practice of organic chemistry. In selecting manuscripts for publication, the editors place emphasis on the quality and novelty of the work, as well as the breadth of interest to the organic chemistry community.