ChemInform Abstract: Original Use of the Same Heterogeneous Chiral Catalyst Batch to Promote Different Asymmetric Reactions.

The main purpose of this review article is to present selected asymmetric synthesis reactions in which chemical and stereochemical outcomes are dependent on the use of an appropriate chiral catalyst. Optically pure or enantiomerically enriched products of such transformations may find further applications in various fields. Among an extremely wide variety of asymmetric reactions catalyzed by chiral systems, we are interested in: asymmetric cyclopropanation, Friedel–Crafts reaction, Mannich and Michael reaction, and other stereoselective processes conducted in the presence of zinc ions. This paper describes the achievements of the above-mentioned asymmetric transformations in the last three years. The choice of reactions is related to the research that has been carried out in our laboratory for many years.

Download Full-text

Combinatorial approach to the discovery of chiral catalysts for asymmetric reactions

Pure and Applied Chemistry ◽

10.1351/pac200577071251 ◽

2005 ◽

Vol 77 (7) ◽

pp. 1251-1257 ◽

Cited By ~ 8

Author(s):

Kuiling Ding

Keyword(s):

Molecular Recognition ◽

Metal Ions ◽

Asymmetric Reactions ◽

Combinatorial Approach ◽

Chiral Catalysts ◽

Chiral Catalyst ◽

Ligand Modification ◽

Highly Efficient ◽

Two Component ◽

Catalyst Systems

The powerfulness of a combinatorial approach in the discovery of novel chiral catalyst systems, particularly for the development of highly efficient, enantioselective, and practical catalysts for asymmetric reactions, was demonstrated by screening modular chiral catalyst libraries created by the strategy of two-component ligand modification of metal ions on the basis of molecular recognition and assembly.

Download Full-text

Silver-catalyzed asymmetric amination of silyl enol ethers

Canadian Journal of Chemistry ◽

10.1139/v00-023 ◽

2000 ◽

Vol 78 (6) ◽

pp. 666-672 ◽

Cited By ~ 43

Author(s):

Yasuhiro Yamashita ◽

Haruro Ishitani ◽

Shu Kobayashi

Keyword(s):

Catalytic Activity ◽

Amino Acid ◽

Asymmetric Synthesis ◽

Asymmetric Reactions ◽

High Catalytic Activity ◽

Enol Ethers ◽

Chiral Catalyst ◽

Silyl Enol Ethers ◽

Catalytic Amination

Catalytic amination of silyl enol ethers with azo diester compounds was investigated. It was shown that Cu(OTf)2 or AgOTf had high catalytic activity and that AgOTf was the most efficient among the catalysts tested in the reactions. In asymmetric reactions, the AgClO4-BINAP system showed high enantioselectivity. In a mixture of toluene or mesitylene and THF, silyl enol ethers reacted with dibenzyl azodicarboxylate (DBnAD) smoothly to afford the corresponding amination adducts in excellent yields with up to 86% ee.Key words: amination, amino acid, asymmetric synthesis, chiral catalyst, silver.

Download Full-text

Metal-, and Organocatalyst-Free One-Pot Assembly of Chiral Aza-Tricyclic Molecules: Creating Six Contiguous Stereocenters from 2-D-Structures and an Amino Acid

10.26434/chemrxiv.12757943.v1 ◽

2020 ◽

Author(s):

Dung Do

Keyword(s):

Amino Acid ◽

Chemical Space ◽

Structural Diversity ◽

Therapeutic Agents ◽

Chiral Molecules ◽

One Pot ◽

Complex Molecules ◽

Chiral Catalyst ◽

Chiral Complex ◽

Free Process

<p>Chiral molecules with their defined 3-D structures are of paramount importance for the study of chemical biology and drug discovery. Having rich structural diversity and unique stereoisomerism, chiral molecules offer a large chemical space that can be explored for the design of new therapeutic agents.<sup>1</sup> Practically, chiral architectures are usually prepared from organometallic and organocatalytic processes where a transition metal or an organocatalyst is tailor-made for desired reactions. As a result, developing a method that enables rapid assembly of chiral complex molecules under metal- and organocatalyst-free condition represents a daunting challenge. Here we developed a straightforward route to create a chiral 3-D structure from 2-D structures and an amino acid without any chiral catalyst. The center of this research is the design of a <a>special chiral spiroimidazolidinone cyclohexadienone intermediate</a>, a merger of a chiral reactive substrate with multiple nucleophillic/electrophillic sites and a transient organocatalyst. <a>This unique substrate-catalyst (“subcatalyst”) dual role of the intermediate enhances </a><a>the coordinational proximity of the chiral substrate and catalyst</a> in the key Aza-Michael/Michael cascade resulting in a substantial steric discrimination and an excellent overall diastereoselectivity. Whereas the “subcatalyst” (hidden catalyst) is not present in the reaction’s initial components, which renders a chiral catalyst-free process, it is strategically produced to promote sequential self-catalyzed reactions. The success of this methodology will pave the way for many efficient preparations of chiral complex molecules and aid for the quest to create next generation of therapeutic agents.</p>

Download Full-text