Abstract Pyrazolinone (I) kondensieren beim Erhitzen mit Aceton (II) zu 4‐Isopropyliden‐Derivaten (III), die mit weiterem Aceton in Gegenwart von Triethylamin Pyranopyrazol‐Derivate (IV) bilden.
Reaction of alkyl α-alkoxymethylene-β-alkoxypropionate and acetamidine yields 2-methyl-4-hydroxy-5-alkoxymethylpyrimidine in a good yield from either cis- or trans-compound. Reaction of alkyl α-methoxymethyleneacetate and acetamidine also gives 2-methyl-4-hydroxypyrimidine in a good yield from either cis- or trans-compound.
Azolium ylides react with dialkyl acylphosphonate to form generally six membered azine derivatives by ring expansion of the azolium heterocycle.This article gives a survey of the reaction with thiazolium, thiadiazolium, oxazolium, oxadiazolium, and imidazolium, and also discusses the relationship of the nature of 4'-suhtituents to the stability and reactivity of thiamine and its analogues in this novel reaction.Many reports have been published on the mechanism of decarboxylation of pyruvate by the enzyme pyruvate decarboxylase, and since the thiazolium ylide hypothesis was proposed by Breslow' interest has especially centred on the formation of 2-suktituted thiazolium compounds by the reaction of thiamine and the related thiazolium salts with various electrophiler.The authors themselves have tried the reaction with aldehyde^,^ a-ketoaldehyde~,~ irocyanate~,~ irothi~cyanates,~ and carbodiimides6 : chemical model experiments for the f i n t step of the decarboxylation reaction.Compared with these electrophiles, dialkyl a~~lphosphonates react with thiamine and related thiazolium salts i n better yields, giving the 3-0x0-2,3-dihydro-4H-thiazine ring system.When applied to other azolium salts,the acylphosphonate reaction proceeds i n almost the same way as with thiazolium, though some differences are observed depending on the character of the azolium salt used.These differences are mostly attributed to the character of heteroatom involved.In this paper we wish to give an outline of our studies on the acylphosphonate reaction with thiazolium, thiadiazolium, oxazolium, oxadiazolium, and imidazolium salk, as the results seem to be interesting for understanding the nature of azolium heterocycles. I. ~hiamine'-IzThis reaction is carried out under basic conditions as i t involves a thiazolium ylide as an intermediate.O u r experimental conditions were as follows: to an ice-cooled suspension o f thiamine hydrochloride i n dry dimethylformamide, three molar amounts of triethylamine and an equimolar amwnt of dialkyl acylphosphonate were added and the mixture was allowed to stand overnight at room temperature under nitrogen atmosphere.Evaporation of the dimethylformamide, extraction with chloroform, washing the chloroform extract with aqueous sodium bicarbonate solution and evaporation of chloroform left yellow crystals of I-phenyl-3(2-hydroxyethyl)-4,9-dimethyl-1,6-dihydropyrimido[4',5'-4,5] pyrimido[2,3-c] [ 1,4] thiazine (Ill) i n 87% yield.W i t h ordinary azolium salts which have no amino group participating i n the reaction center,
Abstract Zahlreiche Phosphordiamide (I) werden in der angegebenen Weise in Anlehnung an bekannte Verfahren in guten Gesamtausbeuten hergestellt und anschließend durch Behandlung mit Ozon und Wasserstoffperoxid in die cyclisierten Hydroperoxide (II) übergeführt.
Abstract Aus dem Butenyl‐phosphordiamidester (I) entsteht bei der Ozonolyse das 4‐Hydroperoxy‐oxazaphosphorin‐2‐oxid (II), das zum 4‐Hydroxy‐isophosphamid (III), einem Metaboliten des tumorhemmenden Phosghamids (IV), reduziert wird.
Based upon the fact that 7-amino-3, 6-dimethylpyrazoio[1, 5-a]pyrimidirie (XIII) possesses effective antipyretic and analgetic action, 14 methyl substitutes of 7-aminopyrazolo[1, 5-a]-pyrimidine in its nuclei were synthesized.With 5-aminopyrazoles (VII-X), 2-methyl-3-ethoxy-3-methoxypropionitrile (I) was reacted to give 6-methyl compounds (XI-XIV), acetoacetonitrile (III) was reacted to give 5-methyl derivatives (XV-XVIII), 2-acetopropionitrile (IV) to 5, 6-dimethyl derivatives (XIX-XXII), and ethyl ethoxymethylenecyanoacetate (V) to 6-ethoxycarbonyl derivatives (XXVII-XXX). In this connection, the cyclization with V in both acidic and alkaline media, and the saponification of XXVII-XXX were investigated. The thermal decomposition of XXXV-XXXVIII produced decarboxyl compounds (XXXIX-XLII) easily. Another synthetic method of XLII was also studied.
Abstract Remarkable substituent effects found in the base‐catalyzed reaction of 5‐methyl‐4‐(1‐methylethylidene)‐2‐(4′‐substituted‐phenyl)‐2,4‐dihydro‐3 H ‐pyrazol‐3‐ones ( 2 ) with acetone at reflux are described.
