Regioselective and stereoselective cyclizations of cyclohexadienones tethered to active methylene groups
作者:Rodolfo Tello-Aburto、Kyle A. Kalstabakken、Kelly A. Volp、Andrew M. Harned
DOI:10.1039/c1ob06125a
日期:——
of 2,5-cyclohexadienones tethered to activated methylene groups was studied. The substitution around the cyclohexadienone ring serves to regioselectively direct these cyclizations based primarily on electronic effects. In the case of brominated substrates, these reactions proceed to give highly unusual electron-deficient tricyclic cyclopropanes. By using a Cinchona alkaloid-based phase-transfer catalyst
Enantioselective Kinetic Resolution/Desymmetrization of
<i>Para</i>
‐Quinols: A Case Study in Boronic‐Acid‐Directed Phosphoric Acid Catalysis
作者:Banruo Huang、Ying He、Mark D. Levin、Jaime A. S. Coelho、Robert G. Bergman、F. Dean Toste
DOI:10.1002/adsc.201900816
日期:2020.1.23
A chiral phosphoric acid‐catalyzed kineticresolution and desymmetrization of para‐quinols operating via oxa‐Michael addition was developed and subsequently subjected to mechanistic study. Good to excellent s‐factors/enantioselectivities were obtained over a broad range of substrates. Kinetic studies were performed, and DFT studies favor a hydrogen bonding activation mode. The mechanistic studies provide