Synlett 2017; 28(11): 1272-1277
DOI: 10.1055/s-0036-1588847
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© Georg Thieme Verlag Stuttgart · New York

Recent Advances in Enantioselective Brønsted Base Organocatalytic Reactions

Bo Teng
Division of Chemistry & Biological Chemistry, School of Physical & Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore   Email: choonhong@ntu.edu.sg
,
Wei Chun Lim
Division of Chemistry & Biological Chemistry, School of Physical & Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore   Email: choonhong@ntu.edu.sg
,
Choon-Hong Tan*
Division of Chemistry & Biological Chemistry, School of Physical & Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore   Email: choonhong@ntu.edu.sg
› Author Affiliations
Further Information

Publication History

Received: 22 March 2017

Accepted after revision: 02 May 2017

Publication Date:
23 May 2017 (online)


Abstract

Enantioselective Brønsted base catalyzed reactions have established themselves as powerful tools for the construction of optically pure compounds. Most strategies aim at improving these reactions involve the modification of substrates to decrease the pK a of the acidic proton. Typically, an electron-withdrawing group such as an ester or a fluorine is placed at the α-carbon, where the proton is also residing. The activation of less active proton, thus, becomes a major challenge in this field of research. In order to overcome this pK a barrier, some new innovative approaches have been demonstrated in recent years. The implementation of dual activation modes and the development of organocatalytic Brønsted superbases are selected to be discussed in this minireview.

1 Introduction

2 Dual Activation Using Lewis Acid and Brønsted Base

3 Dual Activation Using Iminium Catalyst and Brønsted Base

4 Chiral Brønsted Superbase

5 Chiral Ion-Pair Brønsted Base

6 Summary and Outlook