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Author: Subject: Glycine anhydride, its preparation and cleavage to a dipeptide
Boffis
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[*] posted on 4-10-2021 at 08:23
Glycine anhydride, its preparation and cleavage to a dipeptide


In Vogel's "Textbook of organic Chemistry" (5th ed, p1179) there is a description of the preparation of 2,5-ketopiperazine or glycine anhydride by dehydrating glycine. The experiment then goes on to describe the cleavage to the dipeptide glycylglyine and finally the preparation of glycylglycine ethyl ester hydrochloride.

Does anyone know if this reaction is general to most simple amino acids? I can imagine some of the longer chain amino, double ended ones like glutamic acid prefer to form single unit cyclic "anhydrides".

Also does anyone have a title for a book that deals primarily with the chemistry of amino acids as chemicals rather than components of living things? ie and old, pre 1950's book.
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Dr.Bob
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[*] posted on 4-10-2021 at 12:24


Making the anhydride of most amino acids scrambles the stereochemistry (racemizes them). So for most work, that will not work well except for glycine, which has no stereocenter.

Most people now make peptide on resin with Fmoc chemistry, which is easily automated, or if in solution, they use various coupling agents which are found not to racemize the amino acids, like HBTU and many others. There are many books on the subject, I likely have a few left around if you want one or two.
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AvBaeyer
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[*] posted on 4-10-2021 at 19:45


Boffis,

An encyclopedic source for information about amino acids and their chemistry is:

Greenstein and Winitz, "Chemistry of the Amino Acids" in 3 volumes.

I found my practically new set on ABEbooks for not much more than the cost of shipping. There are volumes available now from sellers in Europe and the US.

Highly recommended if you are interested in amino acids.

AvB
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Boffis
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[*] posted on 5-10-2021 at 21:31


@Dr.Bob That's a good point that I hadn't thought about, however, it may not be such a problem. My interest is in the tendency of simple dipeptides to cyclotize when diazotized to give substituted 1,2,3-triazolone (5-hydroxytriazoles). Glycylglcine ester gives the ester of 5-hydroxy-1,2,3-triazole-1-acetic acid, however, I have found another paper that claims that the simple 5-(4)-hydroxytriazole can be similarly prepared from glycinamide, which looks like an easier route. These compounds should not be chiral as they are usually planar.

@AvBaeyer, thank you for this lead I checked out ABE books and came up trumps.
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