Enantioselective Addition of Boronates to Acyl Imines Catalyzed by Chiral Biphenols
作者:Joshua A. Bishop、Sha Lou、Scott E. Schaus
DOI:10.1002/anie.200901023
日期:2009.6.2
On the big screen: A chiralbiphenol catalyst screening protocol was developed for the rapid identification of enantioselective nucleophilic boronate reactions with acylimines (see scheme). The approach successfully identified a unique catalyst for the reaction of aryl, vinyl, and alkynyl boronates. Mechanistic studies demonstrate boronate ligand exchange with the catalyst is necessary for activation
An efficient synthesis of trisubstituted oxazoles via chemoselective O-acylations and intramolecular Wittig reactions
作者:Yi-Ling Tsai、Yu-Shiou Fan、Chia-Jui Lee、Chan-Hui Huang、Utpal Das、Wenwei Lin
DOI:10.1039/c3cc45883k
日期:——
Preparation of new types of trisubstituted oxazoles is realized via chemoselective O-acylations and intramolecular Wittig reactions with ester functionalities using in situ formed phosphorus ylides as key intermediates. A plausible reaction mechanism for this undiscovered chemistry is also proposed based on the existence of expected and rearranged isomeric oxazoles.
Chiral Phosphoric Acid Catalyzed Enantioselective [4 + 2] Cycloaddition Reaction of α-Fluorostyrenes with Imines
作者:Jun Kikuchi、Haiting Ye、Masahiro Terada
DOI:10.1021/acs.orglett.0c03360
日期:2020.11.20
An enantioselective [4 + 2] cycloadditionreaction of α-fluorostyrenes with N-benzoyl imines was demonstrated using a chiral phosphoric acid catalyst. Cycloaddition products having fluorine functionality were formed in high yields with excellent diastereo- and enantioselectivities. Further manipulation of the enantioenriched cycloaddition product with silyl enol ether in the presence of BiCl3 catalyst
使用手性磷酸催化剂证明了α-氟苯乙烯与N-苯甲酰基亚胺的对映选择性[4 + 2]环加成反应。具有氟官能团的环加成产物以高收率形成,具有优异的非对映选择性和对映选择性。在BiCl 3催化剂存在下,用甲硅烷基烯醇醚进一步处理对映体富集的环加成产物,得到的取代产物可通过选择性碳-氟键裂解保留二氢-4 H -1,3-恶嗪骨架,而不会损失对映体过量。
Chiral Brønsted Acid Catalysis for Enantioselective Hosomi−Sakurai Reaction of Imines with Allyltrimethylsilane
The chiralBrønstedacid (1b or 1c) has been shown to initiate the Hosomi−Sakurai reaction of imines with excellent enantioselectivities. The combined Brønstedacid system has been developed to offer a new class of chiralBrønstedacidcatalysis. The present system proceeds through regeneration of the chiralBrønstedacid by proton transfer from additional Brønstedacid to silylated chiral Brønsted