Aminoguanidine derivatives

This ring system may be prepared from 527 by condensation with ami-drazone or aminoguanidine derivatives to afford 528, which on reaction with polyphosphoric acid gave imidaz[5, -/][ ,2,4]triazin-4(2//)one 529... 

The second important reaction path similar to AT synthesis starts with aminoguanidine derivatives (in this case part of a HP) and proceeds via condensation with a synthon Z (see principle in Scheme 8). In a first step l,2,4-triazolo-[4,3-a]pyrimidines (15) are formed these are often isolable and nearly always transformable into the more stable TPs by Dimroth rearrangement. 

Derivatives of rifamycins S and SV of the quinonimine type (Fig. 18), formed by condensation of rifamycin O with aromatic amines (34), hydrazides (35), amidrazones (36) and aminoguanidines (37) 37), showed high in vitro activity against Gram-positive bacteria but poor in vivo absorption 37, 126). The unsubstituted aminoguanidine derivative (38, Fig. 18) displayed especially good broad-spectrum antibiotic properties but was not suitable for oral or parenteral use. 

Cyanamidopyrimidine (15) was converted to the thioureido derivative 16 by reaction with hydrogen sulfide and ammonium hydroxide and then cyclrzed to 18 with hydrazine hydrate. Cyclization to 18 presumably took place by elimination of a molecule of ammonia from the aminoguanidine intermediate 17 (65JCS3357) (Scheme 11). 

Aminoguanidine and Derivatives were first prepd by J. Thiele (Vol l.of Encycl, p A210) (See year 1928 for Nitraminoguanidine and Its Salts)... 

On reduction, nitroguanidine is converted first into nitrosoguanidine and then into aminoguanidine i.e. guanylhydrazine. The latter is used for the manufacture of tetrazene (p. 206), and in organic chemistry to form crystalline derivatives from aldehydes and ketones, just as semicarbazide forms semicarbazones. 

Aminoguanidine and Derivatives, Analytical Procedures. Some info on this subject may be found in the following papers 1)R.P. 

Wm.R. McBride et al,AnalChem 25,1042—6 (1953) CA 47,9862(1953) (Fotentiomeiric titrations of organic derivs of hydrazine. This includes some derivs of aminoguanidine)... 

Aminoguanidine and derivs 1 A210—A214 aminoguanidine and derivs, analytical procedures 1 A214... 

Various extensions are possible (see CHEC 2.19 for full details). Use of aminoguanidines, semicarbazide and thiosemicarbazide gives respectively the 3-amino-1,2,4-triazine, and the 3-one and 3-thione derivatives. Use of a-keto esters and a-keto cyanides gives 5-ones and 5-amino derivatives, respectively. a-Hydroxy ketones afford dihydro-1,2,4-triazines. Intermediates (479) and (480) can sometimes be isolated. 

Reaction of the aminoguanidine 166 with either /3-ketoesters or a-acetyl--y-butyrolactone produced the triazolopyrimidine derivatives 167 and 168, respectively [82JAP(K)57/175193] (Scheme 32). 

Recently, Biemel el al.ns have demonstrated, by means of aminoguanidine and ophenylenediamine derivatives, the lability of carbonyl groups along the carbohydrate backbone, showing that compounds such as l,4-dideoxy-5,6-hexosones are very important Maillard intermediates. 

The following are considered below aminoguanidine, compounds related to amino-guanidine (including dimethyldiguanide), pyridoxamine, OPB-9195, phenacylthia-zolium derivatives, tenilsetam, and flavonoids. 

Dimethylpyrazole has been prepared from acetylacetone and hydrazine hydrate in ethanol3 or hydrazine sulfate in aqueous alkali.4 6 The latter method is preferred, because the reaction with hydrazine hydrate is sometimes violent.3 4 3,5-Dimethyl-pyrazole has also been prepared by hydrolysis and decarboxylation of the 1-carbamido- or 1-carboxamidine derivatives, obtained by reaction of semicarbazide 7 or aminoguanidine 8 with acetylacetone. 

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