Inclusion amino acid ester

Novozymes, a subtilisin produced by Bacillus licheniformis, was used by Chen et al ° to carry out a dynamic kinetic resolution of benzyl, butyl, or propyl esters of DL-phenylalanine, tyrosine, and leucine. The hydrolysis was performed at pH 8.5 in 2-methyl-2-propanol/water (19 1) and the freed L-amino acids precipitated. The key feature bringing about continual racemization of the remaining D-amino acid esters was the inclusion of 20 mmol 1 pyridoxal phosphate. 

Mutihac, L. Buschmann, H. Tudorescu, A. Mutihac, R. Some aspects of extractability and transport of amino acid esters by calixarenes. J. Inclusion Phenom. Macrocycl. Chem. 2003, 47, 123-128. 

If the terminal Hmb-substituted amino acid is glycine then the subsequent residue, even if p-branched, may be coupled through its pentafluorophenyl ester or similar. 151 For any other Hmb amino acid the subsequent residue must be coupled as its symmetric anhydride in dichloromethane. The only limitation to the inclusion of Hmb into a sequence is that 3-branched amino acids will not quantitatively N-acylate a terminal Hmb residue, except glycine, on a practical timescale. 

The rates of hydrolysis of the trifhioroacetates (201 X = H, Me) increase in a nonlinear fashion in the presence of jS-CD. Some differences in rate between the two substrates have been explained as being due to different modes of inclusion.173 The novel CDs (202) and (203) have been synthesized in 45% and 66% yields, respectively, and their complexation with various l/d amino acids have been examined. Importantly, (202) and (203) can be detected by fluorescence spectroscopy and they can recognize the size and shape but also the chirality of the amino acids.174 A /j-CD dimer with a linking bipyridyl group (204) has been synthesized and shown to bind both ends of potential substrates into two different cavities of the CD holding the substrate ester carbonyl group directly above a Cu(H) ion bound to die bipyridyl unit. This achieves... 

Enantioselective Michael addition of thiols to enones is a useful reaction for the synthesis of sex pheromones [26] and terpenes [27]. For example, enantioselective Michael additions of thiols to 2-cyclohexenone (64) and maleic acid esters in the presence of chiral bases such as cinchona alkaloids [28, 29] and optically active amino alcohols [30, 31] have been reported. It has also been found that the enantioselective Michael addition reaction proceeds efficiently in an inclusion crystal... 

Lipids also influence the properties of starch. Like free amino acids, monoglycerides or fatty acid esters of hydroxy acids, lipids form inclusion compounds with amylose (cf. 4.4.4.14.3). Like di- and triglycerides, they also reduce the swelling capacity and solubility by inhibiting water diffusion. Therefore, both degreasing as well as lipid addition are of importance as physical modification methods of starches. 

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