New, highly functionalised (1
E,3
E)-1-(benzoylamino)-4-(dimethylamino)buta-1,3-diene-1,2,3-tricarboxylates proved to be useful and versatile reagents in the formation of highly substituted pyridine,
...N-aminopyridine, pyrrole and pyrido3,4-
cpyridazine derivatives. The formation of the particular type heterocyclic system is dependent on the starting (1
E,3
E)-1-(benzoylamino)-4-(dimethylamino)buta-1,3-diene-1,2,3-tricarboxylate. By an appropriate choice of different ester groups it is possible to drive the reactions towards the formation of either pyridine or pyrrole derivatives.
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Microwave-assisted 2+2 cycloaddition reactions of 2-amino-3-dimethylaminopropenoates with acetylenecarboxylates furnished highly functionalised 1-amino-4-(dimethylamino)buta-1,3-dienes in 40–94% ...yields. All reactions were observed to consistently produce single geometrical isomers, and in cases where non-symmetrical acetylenes were employed the reactions proceeded in a regiospecific manner.
Dimethyl 3-oxopentane-1,5-dioate (dimethyl acetone-1,3-dicarboxylate) (1) was transformed first with (hetero)arenediazonium salts 3a - j into dimethyl 2-(hetero)arylhydrazonopentane-1,5-dioates 4a - ...j followed by reaction with N,N-dimethylformamide dimethylacetal (DMFDMA) to afford, without isolation of intermediates 5a - j, dimethyl 1-(hetero)aryl-4-oxo-1,4-dihydropyridazine-3,5- dicarboxylates 6a - j. An alternative method represents transformation of 1 with DMFDMA into dimethyl 2-(dimethylamino)methylidene-3-oxopentane-1,5-dioate (7) followed by treatment with (hetero)arenediazonium salts 3a - c, j to give pyridazine derivatives 6a - c,j.
(2
E,3Z)-2-(1-Methyl-2,5-dioxoimidazolidin-4-ylidene)-3-(arylamino- or heteroarylamino)methylenesuccinate
5 obtained by 2+2 cycloaddition of (5
...Z)-5-(dimethylamino)methylene-3-methylimidazolidine-2,4-dione (
1) and dimethyl acetylenedicarboxylate (
2) followed by substitution of the dimethylamino group with aromatic or heteroaromatic amines, afforded by heating in ethanol in the presence of potassium hydroxide, potassium salts
6. Acidification of
6 with hydrochloric acid afforded mixtures of (
E)- and (
Z)-isomers of methyl 4-(2-hydroxy-1-methyl-5-oxo-1
H-imidazol-4(5
H)-ylidene)-5-oxo-1-phenyl-4,5-dihydro-1
H-pyrrole-3-carboxylates. On the other hand, alkylation of compounds
6 with methyl iodide or benzyl bromide produced the corresponding methyl (
E)-4-(2-methoxy- or 2-benzyloxy-1-methyl-5-oxo-1
H-imidazol-4(5
H)-ylidene)-5-oxo-1-phenyl-4,5-dihydro-1
H-pyrrole-3-carboxylates
9, derivatives of a new triazafulvalene system.
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Microwave‐assisted 2+2 cycloadditions of acetylene mono‐ and acetylenedicarboxylates 2 to (5Z)‐5‐(dimethylamino)methyleneimidazolidine‐2,4‐dione 4a or to the corresponding thioxo derivative 4b in ...MeCN furnished the highly functionalized imidazolidine‐2,4‐dione derivatives 5 and 6 or the corresponding thioxo derivatives 5–7 as single isomers or mixtures of two isomers (Schemes 2 and 3, Table 1). When the reaction of (5Z)‐5‐(dimethylamino)methyleneimidazolidine‐2,4‐dione (4c) with acetylenedicarboxylate 2a was performed in DMF, hydrolysis of the (dimethylamino)methylene group took place to give (2E)‐2‐(2,5‐dioxoimidazolidin‐4‐ylidene)butanedioate 11 (Scheme 5).
![Regiospecific [2+2] cycload...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0040-4039/small "Regiospecific [2+2] cycloadditions of electron-poor acetylenes to ( Z)-2-acylamino-3-dimethylaminopropenoates: synthesis of highly functionalised buta-1,3-dienes")
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![[2+2] Cycloadditions of Ele...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0018-019X/small "[2+2] Cycloadditions of Electron-Poor Acetylenes to (5Z)-5-[(Dimethylamino)methylene]imidazolidine-2,4-diones")
