Divergent reaction pathways in gold-catalyzed cycloisomerization of 1,5-enynes containing a cyclopropane ring: dramatic ortho substituent and temperature effects

• DOI: 10.1039/c6sc00058d
• Publication Date: 2016-03-04T13:00:11Z
• Authors: Gen-Qiang Chen; Wei Fang; Yin Wei; Xiang-Ying Tang; Min Shi
• Keywords: Cycloisomerization; Cyclopropane

A gold(i)-catalyzed cycloisomerization of easily available 1,5-enynes containing a cyclopropane ring has been developed, efficiently providing cyclobutane-fused 1,4-cyclohexadiene, tricyclic cyclobutene, biscyclopropane and 1,3-cyclohexadiene derivatives in moderate to excellent yields. When the phenyl group was not ortho substituted, 1,4-cyclohexadienes could be produced. With an substituent, three different products selectively synthesized by control temperature used gold(i) catalyst. The 1,5-enyne substrate first undergoes classical enyne form cyclobutene key intermediate, which subsequent transformation produce desired products. plausible reaction mechanism proposed according deuterium labeling experiments intermediate trapping experiments, as well DFT calculations. In our current reaction, substituent on controls outcome effect found originate from steric electronic factors.