Gold-Catalyzed Intramolecular Cyclizations of Cyclopropenes with Propargylic Esters
Peng-Long Zhu1, Xiang-Ying Tang2, Min Shi3
1Key Laboratory for Advanced Materials and Institute of Fine Chemicals East China University of Science and Technology 130 Mei Long Road Shanghai 200237 P. R. China.
Abstract:
Homogeneous gold catalysts are interesting as they can act as potent carbophilic Lewis acids to activate the π bonds of alkynes, allenes, and alkenes. Many impressive applications for the formation of C-C or C-heteroatom bonds have been found due to the excellent functional group compatibility of these catalysts and the air and moisture tolerance of their reactions. Here, we have developed gold-catalyzed novel intramolecular cycloisomerizations of nitrogen or oxygen-tethered cyclopropenes with propargylic esters. The reaction proceeded through different pathways according to different substituent styles, affording 5-azaspiro[2.5]oct-7-enes and bicyclo[4.1.0]heptanes.
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