Glycine hydrolysis

Simple esters cannot be allylated with allyl acetates, but the Schiff base 109 derived from o -amino acid esters such as glycine or alanine is allylated with allyl acetate. In this way. the o-allyl-a-amino acid 110 can be prepared after hydrolysis[34]. The Q-allyl-o-aminophosphonate 112 is prepared by allylation of the Schiff base 111 of diethyl aminomethylphosphonates. [35,36]. Asymmetric synthesis in this reaction using the (+ )-A, jV-dicyclohex-ylsulfamoylisobornyl alcohol ester of glycine and DIOP as a chiral ligand achieved 99% ec[72]. 

The sequence of each different peptide or protein is important for understanding the activity of peptides and proteins and for enabling their independent synthesis, since the natural ones may be difficult to obtain in small quantities. To obtain the sequence, the numbers of each type of amino acid are determined by breaking down the protein into its individual amino acids using concentrated acid (hydrolysis). For example, hydrolysis of the tetrapeptide shown in Figure 45.3 would give one unit of glycine, two units of alanine, and one unit of phenylalanine. Of course, information as to which amino acid was linked to which others is lost. 

A/-(4-Hydroxyphenyl)glycine can be prepared from 4-aminophenol and chloracetic acid (199,200) or by alkaline hydrolysis of the corresponding nitrile with subsequent elimination of ammonia (201). 

Most pteridines are degraded to pyrazines and when they do yield pyrimidines, these may well be the ones from which they were made. However, some useful preparations of pyrimidines from pteridines are known. Thus, reduction of pteridin-7(8//)-one (732) and subsequent hydrolysis yields N-(4-aminopyrimidin-5-yl)glycine (733) (52JCS1620) and hydrolysis of 5,8-dimethylpteridine-6,7(5Ff,8Ff)-dione (734) gives dimethyl-... 

Glycine ethyl ester hydrochloride has been prepared by the action of absolute alcohol and hydrogen chloride on glycine from glycyl chloride and alcohol by the action of ammonia or hexamethylenetetramine on chloroacetic acid, and subsequent hydrolysis with alcoholic hydrochloric acid and by the action of hydrogen chloride and alcohol on methyleneamino-acetonitrile. ... 

Physical techniques can be used to investigate first order reactions because the absolute concentrations of the reactants or products are not required. Dixon et. al [3] studied the base hydrolysis of cobalt complex, [Co(NH3)5L]3+, where L = (CH3)2SO, (NH2)2C = O, (CH3)03P = O in glycine buffers. 

It has been shown that glyeine amides of aminobenzophenones are readily converted to the corresponding benzodiazepines in vivo. Peptides which terminate in such a moiety should thus serve as a benzodiazepine prodrug after hydrolysis by peptidases. One of the glycine residues in lorzafone (194)is presumably removed metabolicaUy in this manner to give a benzodiazepine precursor which spontaneously cyclizes. Acylation of benzophenone 190 with the trityl protected dipeptide 191, as its acid chloride 192, affords the amide 193. Removal of the trityl protecting group with acid yields lorzafone (194) [50]. 

Glycine, ethylene-N,N -bis-2-(0-hydroxyphenyl)-chelating agents iron overload, 6, 769 Glycine, glycyl-hydrolysis... 

An alternative sequence utilized 2-oxazolidone, which was readily synthesized from urea and ethanolamine, as the glycine equivalent. Subsequent treatment with phosphorous acid and formaldehyde produced iV-phosphonomethyl-2-oxazolidone 12 (16). Upon hydrolysis, and loss of CO2,12 provided the related derivative, iV-phosphonomethylethanolamine 13, which was oxidized at high temperature with a variety of metal catalysts including cadmium oxide (16) or Raney copper (17) to give GLYH3, after acidification. A similar oxidation route has also been reported starting from iV-phosphonomethy 1-morpholine (18). 

The value of using the preformed HHT with diphenyl phosphite in this procedure was readily apparent from the nearly quantitative conversion to glyphosate observed from 25. A much lower yield (38%) of glyphosate was obtained after hydrolysis when the same components (ethyl glycinate hydrochloride and formaldehyde) were mixed and heated with neat triphenyl phosphite to give triester 30 (43). 

A number of less elaborate but, nevertheless, quite interesting systems have also been reported where just simple amino acids play a relevant role. Among them is an intriguing report by Komiyama s group [54] in which they describe RNA hydrolysis achieved as a result of the cooperation between carboxylate and ammonium ions. They prepared conjugates of glycine (or iminodiacetate) with an-... 

Another competing cyclisation during peptide synthesis is the formation of aspartimides from aspartic acid residues [15]. This problem is common with the aspartic acid-glycine sequence in the peptide backbone and can take place under both acidic and basic conditions (Fig. 9). In the acid-catalysed aspartimide formation, subsequent hydrolysis of the imide-containing peptide leads to a mixture of the desired peptide and a (3-peptide. The side-chain carboxyl group of this (3-peptide will become a part of the new peptide backbone. In the base-catalysed aspartimide formation, the presence of piperidine used during Fmoc group deprotection results in the formation of peptide piperidines. 

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