Enantioselective TADMAP-Catalyzed Carboxyl Migration Reactions for the Synthesis of Stereogenic Quaternary Carbon
作者:Scott A. Shaw、Pedro Aleman、Justin Christy、Jeff W. Kampf、Porino Va、Edwin Vedejs
DOI:10.1021/ja056150x
日期:2006.1.1
efficient and are used to prepare chiral lactams (23) and lactones (30) containing a quaternary asymmetric carbon. TADMAP-catalyzed carboxyl migrations in the indole series are relatively slow and proceed with inconsistent enantioselectivity. Modeling studies (B3LYP/6-31G*) have been used in qualitative correlations of catalyst conformation, reactivity, and enantioselectivity.
A new strategy, a transient homocoupling dimer strategy, for direct catalytic oxidative cross-enolate coupling reactions is developed. Cross-enolate coupling products bearing a (contiguous) tetrasubstituted carbon center were obtained chemoselectively without the need for stoichiometric amounts of strong bases/metal oxidants, and thus, the present catalysis provides a general method for the synthesis
Dynamic Kinetic Resolution of Azlactones Catalyzed by Chiral Brønsted Acids
作者:Guojian Lu、Vladimir B. Birman
DOI:10.1021/ol102736t
日期:2011.2.4
Chiral Brønstedacids have been shown for the first time to catalyze the dynamic kineticresolution of azlactones. 3,3′-Bis-(9-anthryl)-BINOL phosphoric acid 3c is particularly effective in the case of 4-aryl-substituted substrates, producing 85−92% ee’s.
Catalytic Asymmetric [2+3] Cyclizations of Azlactones with Azonaphthalenes
作者:Chun Ma、Jia‐Yu Zhou、Yi‐Zhu Zhang、Guang‐Jian Mei、Feng Shi
DOI:10.1002/anie.201801349
日期:2018.5.4
The first catalyticasymmetric [2+3] cyclization of azlactones with azonaphthalenes has been established. This strategy allowed the synthesis of a variety of chiral isatin derivatives in generally good yields and excellent enantioselectivities (up to 99 % yield, 98 % ee). The developed reaction has not only established a catalytic enantioselective [2+3] cyclization using azlactones as two‐carbon building
not only in activating the two substrates, but also in controlling the diastereoselectivity of the reaction via hydrogen-bonding interactions. In addition, this protocol demonstrates the great practicability of utilizing p-QMs in dominoreactions. An efficient domino 1,6-addition/intramolecular cyclization reaction between para-quinone methides (p-QMs) and azlactones under Brønsted acid catalysis was