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Updated: Jun 6, 2025
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Published on: June 21, 2017
Tandem Rh(ii)-catalyzed 1,3-acyloxy migration/intermolecular [2 + 2] cycloaddition of electron-deficient propargylic
Zurong Xu1, Dong Zhu2, Rui Wu2
1Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology Guangzhou 510640 China zhusf@scut.edu.cn.
Abstract:
Transition metal-catalyzed 1,3-acyloxy migration of propargylic esters represents one of the most straightforward routes to access allene intermediates, which could engage in various fascinating subsequent transformations. However, this process is often limited to propargylic esters with electron-donating groups due to intrinsic electronic bias, and the subsequent intermolecular reactions are quite limited. Herein, we disclosed an unprecedented Rh2(ii)-catalyzed 1,3-acyloxy migration of electron-deficient propargylic esters, followed by intermolecular [2 + 2] cycloaddition with readily available alkenes and alkynes, and a large array of valuable alkylidenecyclobutane/ene scaffolds could be obtained facilely in one pot. Mechanistic studies revealed that the allene generated from Rh2(ii)-catalyzed 1,3-acyloxy migration of propargylic carboxylates is the key intermediate. Control experiments and NMR data indicated that the formyl group at the terminus of propargylic esters is crucial and the cooperative interactions between the substrate and the carboxylate ligand possibly play significant roles in this reaction.
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