Heterocyclic compounds esters with

Their Esters with Nitrogen-Containing Heterocyclic Compounds... 

Dimethyl acetylenedicarboxylate gave first a similar adduct (2) which then added further molecules of furan yielding (3) and subsequently (4). Between 1931 and 1940 the reactions of acetylenedi-carboxylic acid and its dimethyl ester with a number of nitrogen containing heterocyclic compounds were examined, and structures were proposed for the products. Apart from an unpublished investigation of the products from pyridine and dimethyl acetylenedicar-... 

III. Reactions of Acetylenic Acids and Esters with Individual Nitrogen-Containing Heterocyclic Compounds... 

In this review an attempt is made to discuss all the important interactions of highly reactive divalent carbon derivatives (carbenes, methylenes) and heterocyclic compounds and the accompanying molecular rearrangements. The most widely studied reactions have been those of dihalocarbenes, particularly dichlorocarbene, and the a-ketocarbenes obtained by photolytic or copper-catalyzed decomposition of diazo compounds such as diazoacetic ester or diazoacetone. The reactions of diazomethane with heterocyclic compounds have already been reviewed in this series. ... 

Reactions of Acetylenecarboxylic Acids and Their Esters with Nitrogen-Containing Heterocyclic Compounds R, M. Achbson... 

Hoesch reaction. In most cases, a Lewis acid is necessary zinc chloride is the most common. The reaction is generally useful only with phenols, phenolic ethers, and some reactive heterocyclic compounds (e.g., pyrrole), but it can be extended to aromatic amines by the use of BCls. Acylation in the case of amines is regioselectively ortho. Monohydric phenols, however, generally do not give ketones " but are attacked at the oxygen to produce imino esters. Many nitriles... 

The recently reported (757) conversion of 5-pyrazolones directly to a,j8-acetylenic esters by treatment with TTN in methanol appears to be an example of thallation of a heterocyclic enamine the suggested mechanism involves initial electrophilic thallation of the 3-pyrazolin-5-one tautomer of the 5-pyrazolone to give an intermediate organothallium compound which undergoes a subsequent oxidation by a second equivalent of TTN to give a diazacyclopentadienone. Solvolysis by methanol, with concomitant elimination of nitrogen and thallium(I), yields the a,)S-acetylenic ester in excellent (78-95%) yield (Scheme 35). Since 5-pyrazolones may be prepared in quantitative yield by the reaction of /3-keto esters with hydrazine (168), this conversion represents in a formal sense the dehydration of /3-keto esters. In fact, the direct conversion of /3-keto esters to a,jS-acetylenic esters without isolation of the intermediate 5-pyrazolones can be achieved by treatment in methanol solution first with hydrazine and then with TTN. 

In a paper concerned primarily with the use of epoxyalkylphosphonates in the synthesis of heterocyclic compounds, the (epoxyalkyl)phosphonic esters have been obtained, accompanied by (2-oxoalkyl)phosphonic esters (81) in the reaction... 

Nitroketene dithioacetal reacts with anthranilic esters to afford quinolone derivatives, which are converted into diazepinones by reductive cyclization. The review by Kolb covers synthetic application of nitroketene dithioacetal for heterocyclic compounds (see Scheme 10.26).145... 

Extending oils for compounds crosslinked with peroxides have to be carefully selected. Synthetic ester plasticisers such as phthalates, sebacates and oleates may be used in combination with crosslinking peroxides without affecting the crosslinking reaction. Some derivatives of alkylated benzenes are also known for their very low consumption of free radicals, which is clearly desirable. Mineral oil with double bonds, tertiary carbon atoms or containing heterocyclic aromatic structure may react with radicals paraffinic mineral oils are more effective than naphthenic types, which usually require extra treatment in order to guarantee optimum results when used in peroxide crosslinked blends. 

Heterocycles.—The phosphonium salt (59) is an effective three-carbon synthon, as demonstrated by its reaction with enolates of /9-keto-esters (Scheme 20) to give cyclopentenyl sulphides via an intramolecular Wittig reaction.63 Ylides are also intermediates in the synthesis of dihydrofurans (60) from the cyclopropylphos-phonium salt (61) and sodium carboxylates (Scheme 21).64 Cumulated ylides are very useful for the synthesis of heterocyclic compounds, e.g. (62), from molecules which contain both an acidic Y—H bond and a carbonyl or nitroso-function, as shown in Scheme 22.65... 

Chen and co-authors in their work [50] offered key stages for mechanism of heterocyclization leading to compounds 25 and 26 (Scheme 12). The reaction sequence for azolopyrimidines 25 formation is very similar to that published in [47] and presented in Scheme 9. Pathway to tetrahydroderivatives 26, in opinion of [50], also includes at the beginning Knoeveganel condensation. Further step of the reaction in this case should be the addition of exocyclic NH2 group of aminoazole to enone fragment of unsaturated ester, with subsequent cyclization of the adduct formed into final tetrahydropyrimidine (Scheme 14). 

Numerous reactions of acetylenic esters are reported in the literature, and many of these lead to heterocyclic compounds. Acetylenic esters undergo very facile addition reactions with several nucleophiles and also they participate as dipolarophiles in 1,3-dipolar cycloadditions, and as... 

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