Metalla‐Claisen Rearrangement in Gold‐Catalyzed [4+2] Reaction: A New Elementary Reaction Suggested for Future Reaction Design

We report the first computational evidence for the involvement of metalla-Claisen Rearrangement (MCR) in the gold-catalyzed [4+2] reaction of yne-dienes, together with detailed analysis of different pathways and their competition. Such a MCR does not take place when the reaction is run under rhodium catalysis. The reasons behind this are given.

Abstract

We report here computational evidence for a metalla-Claisen rearrangement (MCR) in the case of gold-catalyzed [4+2] cycloaddition reaction of yne-dienes. The [4+2] reaction starts from exo cyclopropanation, followed by MCR and reductive elimination. The cyclopropane moiety formed in the first step is crucial for a low barrier of the MCR step. In addition, the importance of an appropriate combination of the tether group and the terminal substituent on alkyne in the yne-diene substrates was studied. The mechanism of rhodium-catalyzed [4+2] reaction of yne-dienes was also investigated to see whether an MCR mechanism is involved or not. The findings and new understanding hereby reported represent an important advance in the catalysis field.

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