Biomimetics strategy

Guan Z, Roland JT, Bai JZ, Ma SX, Mclntire TM, Nguyen M. Modular domain structure a biomimetic strategy for advanced pol3mieric materials. J Am Chem Soc 2004 126 2058-2065. 

Aminocatalysis is a biomimetic strategy used by enzymes such as class I aldolases. Application of aminocatalysis in an asymmetric aldol reaction was reported in the early 1970s. Proline (19) efficiently promoted an intramolecular direct aldol reaction to afford Wieland-Miescher ketone in 93% ee [17,18]. More than 25 years later, in 2000, List, Barbas, and co-workers reported that proline (19) is also effective for intermolecular direct aldol reactions of acetone (le) and various aldehydes 3. Notably, the reaction proceeded smoothly in anhydrous DMSO at an ambient temperature to afford aldol adducts in good yield and in modest to excellent enantioselectivity (up to >99% ee, Scheme 9) [19-22]. The chemical yields and selectivity of proline catalysis are comparable to the best metallic catalysts, although high catalyst loading (30 mol %) is required. Proline (19)... 

Das, S., Brudvig, G. W., Crabtree, R. H., Molecular recognition in homogeneous transition metal catalysis a biomimetic strategy for high selectivity. Chem. Commun. 2008,413-424. 

Fig. 11 Synthesis of 25 via (a) intermediate 42, also utilized in 24 and 58 synthesis and (b) a biomimetic strategy from salicylnitrile 61 and L-cysteine 29...

Another example of a partially biomimetic strategy is shown in Fig. 25b. Here the analogy is to the starting materials two indole-containing molecules, 136 and 137, which were dimerized via formation of the same bond as seen in the reaction carried out by StaD on two molecules of indole-3-pyruvic acid imine (125). This bond - between the (3-carbons of the L-tryptophan precursor (123) - once formed biosynthetically leads to 127, which spontaneously forms chromopyrrolic acid (128) in oxygen (Fig. 24). In the biosynthetic route, this reaction is between two unactivated carbons, which would seem to render it challenging, although low levels of 128 formation are seen between indole-3-acetic acid, L-tryptophan, and... 

Note that the above-mentioned, rather simplified set of characteristics for a biomimetic strategy of guided cell adhesion were first developed for planar surfaces. For many cell-types, this accounts for an interesting model system with a sufficient relevance to the biological situation however, there also exist a number of cell types that might behave differently with respect to surface attachment, growth,... 

Nicolaou KC, Montagnon T, Snyder SA (2003) Tandem reactions, cascade sequences, and biomimetic strategies in total synthesis. Chem Commun 5 551... 

The isolation of the batzelladines attracted the attention of several groups, and some work has appeared in recent years concerned with partial syntheses, mainly in the racemic series 17, 18, 19]. The efforts of Snider culminated in a nine-step synthesis of racemic batzelladine E, following the biomimetic strategy [ 18bj. The only enan-tioselective synthesis reported to date established the absolute. stereochemistry of batzelladine B (Scheme 10) [20a], Diol 39 (obtained by /(-keto ester chemistry) was transformed into guanidine 41 via the diazide. An improved Biginelli type condensation with methyl acetoacetate in tri-... 

The pyrroloquinoline alkaloid family of bioactive marine natural products has been assembled by exploiting a biomimetic strategy. In the case of the iV-benzyl derivative of discorhabdin C (281a), for example, the cation 282 that is formed upon electrooxidation of dibromophenol 279 was intercepted intramolecularly to afford 281a in modest 19% yield [70]. Unfortunately, all attempts to remove the benzyl group failed. Consequently, the approach to the natural product was modified to affect debenzylation earlier in the scheme. Electrochemical oxidation of the free amine 280 did lead to discorhabdin C (281b), albeit in a low yield (24%). 

Tandem reactions, cascade sequences, and biomimetic strategies in total synthe-sis 03CC551. 

Kim, H.M. (2003) Ceramic bioactivity and related biomimetic strategy. Curr. Opin. Solid State Mater. Res., 7, 289 - 299. 

Fig. 10.3-13 A biomimetic strategy for transamination at pH 6.5 and at 22-37 °C. N-terminal modification. After condensation The resulting pyruvamides can be further with pyridoxal phosphate (PLP), a variety of derivatized through oxime formation. N-terminal amino acids undergo oxidative...

Consequently, the scope of this chapter is to give an overview on the current developments of biomimetic polymers in biomedical applications including an introduction on cell-biomaterial interactions, applied biomimetic strategies, and synthesis and modification techniques for seleaed natural and S3mthetic polymers. Examples of recent studies using... 

Figure 4.1 Synthesis of bone-like composites through a biomimetic strategy inspired from bone biomineralization, (a) Biomimetic composites were obtained by first cross-linking maleic chitosan with PEGDA under UV light in water to form 3-D hydrogel networks, followed by biomimetic mineralization Images of maleic chitosan/PEGDA hydrogel (b) before and (c) after mineralization.

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