Rhodium-Catalyzed Intramolecular Cyclopropanation of α-Diazo β-Keto Nitriles Containing an Unsaturated Substituted Cycloalkyl GroupSupported by: Ministry of Science and Technology of Taiwan (MOST 104-2113-M-259-001)
Received: 13 February 2017
Accepted after revision: 19 March 2017
07 April 2017 (eFirst)
Several α-diazo β-keto nitriles bearing trans-2-allyl-, -vinyl-, or -phenylcycloalkyl groups were prepared and their intramolecular cyclopropanation reactions were examined. In the presence of Rh2(OAc)4 (1 mol%) as a catalyst, the allyl- and vinyl-substituted precursors were found to undergo cyclopropanation smoothly at ambient temperature to afford novel tricyclic α-keto cyclopropyl nitriles in 47–88% yields with diastereomeric ratios ranging from 79:21 to >99:1. On the other hand, the catalytic reactions of the phenyl-containing analogues did not give any cyclopropyl products, but instead provided functionalized hexahydrophenanthrene or tetrahydrocyclopentanaphthalene derivatives in quantitative yields.