GB811780A - Hydrazides and thiosemicarbazones - Google Patents

Abstract

The invention comprises compounds of the formula <FORM:0811780/IV (b)/1> (wherein R is -CH=NNHCSNH2 or R and R1 are jointly H2NCSNHN =, R2 being -H, -NH2 or -NHCOCH3 and R3 being -COOC2 H5; or R is -CONHNH2, R1 and R2 being -H, -NH2 or -NHCOCH3 and R3 being -COOH or -CONHNH2, and n is 1, 2 or 3, at least one of the groups R1 and R2 being -NH2 or -NHCOCH3 when R and R3 are both -CONHNH2), the preparation of the dihydrazides by heating the corresponding dimethyl or di-ethyl esters with excess of hydrazine hydrate, with or without alcohol solvent, the preparation of the monocarboxy mono-hydrazides by treating the corresponding mono-carboxy mono-(methyl or ethyl) esters with an excess of hydrazine hydrate in the cold, bringing the liquid to dryness and taking the residue up in acetone, and hydrolysing the mono-hydrazide isopropylidene derivative thus obtained with HCl in acetone-ether or ether solution, and the preparation of the thiosemicarbazones by reacting the corresponding aldehydes with an excess of thiosemicarbazide in water-alcohol solution. In examples: (1) monoethyl adipate is left to stand with excess hydrazine hydrate, the excess of hydrazine is removed, the mixture is refluxed with acetone to give adipic acid isopropylidene-mono-hydrazide and this is hydrolysed with HCl in ether to give adipic acid monohydrazide hydrochloride; (2) pimelic acid monohydrazide hydrochloride is similarly prepared; (3) L-glutamic acid diethyl ester is refluxed with hydrazine hydrate in ethanol to give L-glutamic acid dihydrazide; (4) 2 : 5-diamino-adipic acid dimethyl ester hydrochloride is refluxed with potassium acetate and acetic anhydride to give 2 : 5-diacetylamino-adipic acid dimethyl ester, which on refluxing with hydrazine hydrate in ethanol gives 2 : 5-diacetylamino-adipic acid dihydrazide; (5) 2 : 6-dibromopimelic acid diethyl ester is refluxed with potassium phthalimide in dimethyl formamide to give 2 : 6-diphthalimido-pimelic acid diethyl ester, this on hydrolysis with hydrazine hydrate and then HCl gives 2 : 6-diamino-pimelic acid hydrochloride (and, as a by-product which is removed, 1 : 4-dihydroxyphthalazine), this on refluxing with ethanol in presence of anhydrous HCl gives 2 : 6-diaminopimelic acid diethyl ester hydrochloride, this on acetylation with acetic anhydride and pyridine at 20 DEG C. gives 2 : 6-diacetylamino-pimelic acid diethyl ester, and this on refluxing with hydrazine hydrate in ethanol gives 2 : 6-diacetylamino pimelic acid dihydrazide; (6) 2-amino-pimelic acid is boiled with HCl-saturated ethanol, the product is reacted with acetic anhydride in pyridine to give 2-acetylamino-pimelic acid diethyl ester and this is converted to 2-acetylaminopimelic acid dihydrazide by the method of (3); (7) ethyl 6-formyl-caproate is refluxed with thiosemicarbazide in ethanol to give the thiosemicarbazone; and (8) the thiosemicarbazone of ethyl 5-formylvalerate is similarly prepared.