Aryne 1,4-Disubstitution and Remote Diastereoselective 1,2,4-Trisubstitution via a Nucleophilic AnnuIation-5,5-Sigmatropic Rearrangement Process

摘要

Both aryne 1,4-disubstitution and 1,2,4-trifunc-tionalization were accomplished from tertiary amines bearing a penta-2,4-dien-1-yl moiety. These transformations could directly incorporate a C-N and a C-C bond para to each other on an aryne intermediate via a sequential nucleophilic addition and [5,5]-sigmatropic rearrangement. When arynes bearing 3-tethered electro-philes were employed, a cascade regioselective nucleophilic addition, intramolecular cyclization, and remote diastereoselective [5,5]-sigmatropic rearrangement process was observed. Our density functional theory (DFT) calculations revealed that hydrogen-bonding interactions between two C-H hydrogens on the penta-2,4-dien-1-yl chain and the oxygen anion generated upon N-nucleo-philic annulation reaction in the [5,5]-sigmatropic rearrangement step is responsible for the remote diastereoselective control in this reaction system.