D-phenylalanine

A synthesis for the enantiomerically pure 535 was developed starting with D-phenylalanine which upon reaction with methyl chloroformate gave 528 whose reaction with methoxylamine afforded 529. Cyclization with bis(trifluoroacetoxy)iodobenzene in presence of trifluoroacetic acid gave the tetrahydroquinoline derivative 530 which was demethoxylated to give 531. Treatment of 531 with either benzyl chloroformate or... 

Different optical enantiomers of amino acids also have different properties. L-asparagine, for example, tastes bitter while D-asparagine tastes sweet (see Figure 8.3). L-Phenylalanine is a constituent of the artificial sweetener aspartame (Figure 8.3). When one uses D-phenylalanine the same compound tastes bitter. These examples clearly demonstrate the importance of the use of homochiral compounds. 

CJH7CIO 103-80-0) see Bendroflumethiazide Moxaverine Phenacemide Phenazocine D-phenylalanine... 

C HiiNOj 63-91-2) see Melphalan Quinapril hydrochloride Saquinavir L-phenylalanine fert-hutyl ester hydrochloride (CijHtoCINOj 15100-75-1) see Alacepril D-phenylalanine methyl ester (CioHijNOj 21685-51-8) see Nateglinide L-phenylalanine methyl ester hydrochloride (C10H14CINO2 7524-50-7) see Angiolensinatnide... 

No compound other than the methyl ester of N-benzoyl-Lphenylalanine, 33, is an obvious choice for an open-chain analog of the locked substrate 25 but D-24, on the other hand, may be a locked analog of either N-benzoyl-D-alanine methyl ester 34 or of N-formyl-D-phenylalanine methyl ester 35 (75). If 24 is an analog of 34 rather than 35, the comparison of the two locked analogs made in Section V.B. is not valid the phenyl of 24 would then correspond to the benzoyl phenyl of 34. 

D Winne. The influence of blood flow on the absorption of L- and D-phenylalanine from the jejunum of the rat. Arch Pharmacol 277 113-138, 1973. 

The molecular scaffolds also provide an unusual opportunity for the identification and recognition of meso structures. For example, successive acylation of L and D phenylalanine with the acridine diacid gives the structure 56 and we anticipate that... 

R. Fernandez-Lafuente, V. Rodriguez, and J.M. Guisan, The coimmobilization of D-amino acid oxidase and catalase enables the quantitative transformation of D-amino acids (D-phenylalanine) into alpha-keto acids (phenylpyruvic acid). Enz. Microb. Technol. 23, 28-33 (1998). 

In a different approach, Lin et al. have used particles derived from a ground MI-bulk polymer and mixed with a polyacryl amide gel for chiral separation. Using a polymer imprinted with L-phenylalanine, D-phenylalanine could be separated from the template with a separation factor of 1.45 [35]. Although the combination of MIP with capillary electrochromatography is still not widely used, the ability to separate enantiomers in nanoliter samples promises interesting developments for the future. 

Albanese and co-workers33 have carried out a series of investigations on the utilization of D-amino acids by humans. In the investigation of the utilization of D-phenylalanine, individual differences appeared which were so striking as to call for special attention. Vari-... 

Phenylalanine behaves differently from valine in permethylated /3-CD. Both L-and D-phenylalanine interact in the same way. In fact, the predominant interaction of... 

Molecular modeling calculations give important insight into the origin of such a large enantioselectivity. Unlike the rigid /3-CD, the hnear maltoheptaose allows each enantiomer of phenylalanine to find the most favorable conformation. The phenyl group of L-phenylalanine is oriented towards the C6 center of the hosts, while that of D-phenylalanine is oriented towards the C2 and C3 centers of the hosts. 

Insulin Exenatide is not a substitute for insulin in insulin-requiring patients. Do not use exenatide in patients with type 1 diabetes or for the treatment of diabetic ketoacidosis. The concurrent use of exenatide with insulin, thiazolidinediones, D-phenylalanine derivatives, meglitinides, or alpha-glucosidase inhibitors has not been studied. 

A number of variations on this type of coating have been prepared and offer some improvement over the original phase. Figure 11.11 shows the volatile pentafluoropropionamide-trifluoroethyl ester (PFP-TFE) derivatives of L and D phenylalanine. Figure 11.12 shows the separation of PFP-TFE derivatives of the D and L enantiomers of the amino acids phenylalanine and p-tyrosine on a Chirasil Val column, the D(/ )-enantiomers elute first. Chirasil Val generally performs best for the separation of enantiomers of amino acids, for many other compounds it is not as effective. 

Amino acids Scientific data show a substantial health benefit for D-phenylalanine as an analgesic. 

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