Gold(I)- and Yb(OTf)(3)-cocatalyzed rearrangements of epoxy alkynes: transfer of a carbonyl group in a five-membered carbocycle.
We report here the intramolecular reactions between alpha,beta-epoxy ketones and alkynes cocatalyzed by gold(I) and Yb(OTf)(3). This new catalytic system based on a combination of gold(I) and Yb(OTf)(3) allows facile transformation of epoxy alkynes to give novel indene derivatives in moderate to good yields under mild conditions. Moreover, we describe here the first observation of a transfer of a carbonyl group in a five-membered carbocycle during gold-catalyzed reactions. This proposed mechanism is corroborated by isotope-labeling experiments (D and (13)C). Furthermore, the probable role of each catalyst in this interesting domino reaction has been examined by (31)P NMR experiments. The utilization of gold catalysts combined with rare-earth metal salts offers a new concept for the design of catalyst combinations for domino or cascade reactions.
Dai
Lun-Zhi
LZ
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China.
Shi
Min
M