Approaches to the synthesis of enzyme model systems. Regioselective transacylation reactions between thiol-containing crown ethers and amino acid ester salts
✍ Scribed by Takeaki Matsui; Kenji Koga
- Book ID
- 104245556
- Publisher
- Elsevier Science
- Year
- 1978
- Tongue
- French
- Weight
- 221 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0040-4039
No coin nor oath required. For personal study only.
✦ Synopsis
Received in Japsn 30 Jbacernber 1977; reoeived in UK for plblio8tiofi 9 FebmW 1978) Enzymes, enormously effective catalysts for biological reactions, are known to combine with their substrates to form highly structured enzyme-substrate complexes as an essential step in their catalytic reactions. 1) Evaluating complex formation as one of the possible strategies to effect reactions highly effectively, investigations have hitherto been reported on the utility of macrocyclic compounds such as cyclodextrins, 2) cyclophanes, 3) cyclic peptides, 4) crown ethers, 3) etc,6) as hosts to catch guests in solution.
Recently, Cram and his co-workers have reported enantioselective transacylation reactions between a-amino acid p-nitrophenyl ester salts and optically active crown ethers having built-in sulfhydryl groups as catalytic sites. 7) The present paper describes the result of examinations on the regioselectivity in the transacylation reactions between crown ethers (1, 2, 3J having function-Clr alized side arms of different length and a-, N-methyl-a-, B-, Y-, and s-amino acid p-nitrophenyl ester salts (5, 2, A, 3 8). These crown ethers were designed to show regioselectivity by the expectation that cyclic polyether part would act as a binding site, side arms constructed with ether oxygen and/or methylene as regio-recognition sites , and sulfhydryl groups at the end of the side arms as catalytic sites.