Patent GB-781438-A (GB)
Title: 4-substituted 1.2-diphenyl-3.5-dioxo-pyrazolidines and process for their production
Filed: 1955-09-08
Abstract: The invention comprises compounds of the general formula <FORM:0781438/IV (a)/1> (wherein n is a whole number greater than 1) and their salts with inorganic or organic bases, and the preparation thereof by condensing hydrazobenzene, or a derivative thereof having an N-substituent which can be easily split off, with a malonic acid derivative of one of the following general formulae <FORM:0781438/IV (a)/2> (wherein X represents a radical easily split off, Y represents chlorine, bromine or an acyloxy radical and R represents a radical convertible, and subsequently converted, to HO-CnH2n-by hydrolysis and/or reduction or by hydrogenolysis, or with a dialkyl ester or the lactone of a monoalkyl ester of a hydroxyalkyl malonic acid of the general formula <FORM:0781438/IV (a)/3> or by the action of an alkylene oxide on 1:2-diphenyl - 3 : 5 - dioxopyrazolidine in the presence of a condensing agent or on an alkali metal salt of 1 : 2-diphenyl-3 : 5-dioxopyrazolidine, followed in each case, if desired, by conversion of the products into their salts with inorganic or organic bases.  The first of these processes (in which, in addition to hydrazobenzene itself, there may be used an N-acyl, N-alkali metal or N-alkaline-earth metal monohalide derivative thereof) is preferably effected in the presence of an acid-binding agent when acid is split off, or in the presence of a condensing agent such as a metal alcoholate when alcohol is split off, these agents being added successively when the reaction proceeds in stages, as with an ester halide. Those of the products in which the HO-CnH2n-group is of the form <FORM:0781438/IV (a)/4> (wherein m is 0 or 1 and R1,R2 and R3 represent hydrogen or alkyl radicals) readily tautomerize to lactones of the general formula <FORM:0781438/IV (a)/5> e.g. on recrystallization from an organic solvent or treatment with dilute acids.  In examples: (1) 3 : 3-ethylenedioxybutylmalonic acid diethyl ester is condensed with hydrazobenzene in benzene in the presence of sodium ethoxide, and the product is converted by hydrolysis followed by reduction with NaBF4 or with hydrogen and Raney nickel to 1 : 2-diphenyl4 - (31 - hydroxybutyl) - 3 : 5 - dioxopyrazolidine (lactone form); (2) 4-tetrahydropyranyl(a ) - oxybutylmalonic acid diethyl ester is similarly reacted and the product hydrolysed to 1 : 2 - diphenyl - 4 - (41 - hydroxybutyl)-3 : 5 - dioxopyrazolidine; (3) the same product is obtained by refluxing 4-hydroxybutylmalonic acid diethyl ester with hydrazobenzene and sodium methoxide in benzene; (4) 1:2-diphenyl - 3 : 5 - dioxopyrazolidine is heated in an autoclave with a solution of ethylene oxide in diethyl carbitol to produce 1 : 2-diphenyl-4-(21 - hydroxyethyl) - 3 : 5 - dioxopyrazolidine (isolated in the lactone form by recrystallization from aqueous methanol, and characterized by acetylation with acetic anhydride and sodium acetate to form 1 : 2-diphenyl-4-(21-acetoxyethyl) - 3 : 5 - dioxopyrazolidine).  The products are useful as antipyretic, analgesic and antiphlogistic agents.  Starting material.  4-Tetrahydropyranyl-(a )-oxybutylmalonic acid diethylester is produced from 4-hydroxybutylmalonic acid diethyl ester, dihydropyran and a little conc.  HCl.  Specifications 646,597 and 781,439 are referred to.