1.1.3.3- Tetraethoxypropane, reaction

The synthesis of 2-substituted pyrimidines from 1,3-dicarbonyl compounds and urea derivatives was first described by Evans2 and was later improved by Hunt, McOmie, and Sayer3 for the preparation of 2-mercapto-4,6-dimethylpyrimidine. Burness4 employed 3-ketobutyraldehyde acetal in this procedure to give 2-mercapto-4-methylpyrimidine. 2-Mercaptopyrimidine has been prepared from 1,1,3,3-tetraethoxypropane and thiourea by variations of this basic method 3 6 6 as well as by the reaction of 2-chloropyrimidine with thiourea 1 or sodium hydrosulfide.8... 

The fully aromatic and unsubstituted pyrimido[ 1,2-6 ]pyridazinium perchlorate (171) has been prepared by the condensation of 3-aminopyridazine (170) with 1,1,3,3-tetraethoxypropane in the presence of polyphosphoric acid. The product was precipitated from the reaction mixture by treatment with perchloric acid and ice. Several alkyl, aryl and halogenated derivatives of this ring system have also been prepared (71JOC2457). 

Monobromination of 2,4-dimethylbenzodiazepine in a mixture of acetic acid and nitromethane provided a deep blue salt, which was designated as 3-bromo-2,4-dimethylbenzodiazepinium bromide (62JPR156). However, an alternative product, which was brown-yellow, was obtained from the reaction of o-phenylenediamine with 2-bromo-l,l,3,3-tetraethoxypropane (62JPR156). 

Guanidino compounds can be readily cyclized by reaction with malondialdehyde, either as such or in the form of its diethyl acetal, 1,1,3,3-tetraethoxypropane, giving substituted pyrimidines, which may have improved chromatographic properties increased detectability (UV absorption after TLC) and potentially also increased volatility for analysis by GC [93,94],... 

Tetraethoxypropane (malonaldehyde tetraethylacetal) (XII-41) and diethyl malonate in acetic anhydride give diethyl 3-ethoxyallylidenemalonate (Xn-42), which cyclizes ii polyphosphoric acid or formic acid to the pyrone XII-43. Reaction of W42 with ammonia w henzylamine forms 3-aminoallylidenemalonates (XII-44 R = H, GHjCgHs), which are cyclized to the ethyl a-pyridone-3carhoxylates (XII-4S) in alcoholic sodinm ethoxide or piperidine. ... 

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