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Asymmetric organocatalysts peptides

The use of L-proline, amides derived from it, and related amino acids and small peptides as asymmetric organocatalysts for aldols - and indeed many other reactions mentioned elsewhere in this chapter - expanded hugely in 2006. A review deals with the direct aldol case.96... [Pg.14]

For a recent review on amino acids and peptides as asymmetric organocatalysts see E. R. Jarvo, S. J. Miller, Tetrahedron 2002, 58, 2481-2495. [Pg.346]

Jarvo ER, Miller SJ (2002) Amino acids and peptides as asymmetric organocatalysts. Tetrahedron 58 2481-2495... [Pg.192]

In conclusion, the aldol reaction with L-proline as an enzyme mimic is a successful example for the concept of using simple organic molecules as chiral catalysts. However, this concept is not limited to selected enzymatic reactions, but opens up a general perspective for the asymmetric design of a multitude of catalytic reactions in the presence of organocatalysts [1, 3]. This has been also demonstrated by very recent publications in the field of asymmetric syntheses with amino acids and peptides as catalysts. In the following paragraphs this will be exemplified by selected excellent contributions. [Pg.182]

An interesting new development came with the realisation of Miller that a range of enan-tioselective reactions for which peptides based on the imiodazole sidechain of histidine were used as organocatalysts could possibly serve as a model for the asymmetric intramolecular Michael-Stetter reaction as well [32]. To this end. Miller synthesised thiazole based peptide-modified organocatalysts that can be described as having a thio-histidine as the crucial anuno acid (see Hgure 6.7). The respective amino acid was reported as thiazolylalanine (Taz). [Pg.313]

Figure 6.7 Thiazole modified peptides as organocatalysts for the asymmetric intramolecular... Figure 6.7 Thiazole modified peptides as organocatalysts for the asymmetric intramolecular...
In contrast to the early recognition of the importance of proline and proline-based secondary amine peptide catalysts as enzyme mimics, the potential of primary amines in asymmetric catalysis was much underestimated at that time, probably because of their known lower basicity in comparison to secondary amines. This is particularly surprising taking into consideration the fact that primary amino acid catalysis is of enormous importance in enzyme catalysis. For example, primaiy amines occur in the catalytic sites of several enzymes, such as type I aldolases, dehydratases, and decarboxylases. Therefore, primary amines as organocatalysts possess particular appeal. [Pg.325]

The development of catalytic strategies towards the enantioenriched generation of p-hydroxy ketones via an aldol reaction was intensively promoted in recent years. In particular, the application of proline and proline-based amides and peptides as organocatalysts for the asymmetric direct aldol reaction was successfully investigated, by contributions from several researchers. ... [Pg.328]

Since the introduction of the first peptide organocatalyst in the 1980s, a considerable number of new peptide frameworks have been developed that are able to effectively catalyse several important transformations including alcohol esterifications, 1,4-conjugate additions, aldol reactions, Strecker synthesis, asymmetric cyanohydrin synthesis and alkene epoxidation are discussed. A few successful examples of solid-supported peptides and reactions in ball milling under solvent-free conditions have been demonstrated. These methods combine the advantages of being economically and environmentally friendly processes. [Pg.347]


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See also in sourсe #XX -- [ Pg.347 ]

See also in sourсe #XX -- [ Pg.347 ]




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