Gold-Catalyzed Intramolecular Cyclizations of Cyclopropenes with Propargylic Esters.
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.
Key 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.
Peng-Long
PL
Zhu
State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic Chemistry Chinese Academy of Sciences 345 Linglin Lu Shanghai 200032 P. R. China.
Xiang-Ying
XY
Tang
Key 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; State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic Chemistry Chinese Academy of Sciences 345 Linglin Lu Shanghai 200032 P. R. China.
Min
M
Shi
cationic intermediates; cyclopropenes; gold carbenes; gold catalysis; propargylic esters