ISSN:
0170-2041
Keywords:
Nitrilimines
;
1,3-Dipolar cycloadditions
;
Di[1,2,4]triazolo-pyrazines
;
1,2,4-Triazolo-pyrimidines
;
Spiro[pyrimidine-4(1H),2′(3H)-[1,3,4]thiadiazoles]
;
Cycloadditions, 1,3-dipolar
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Reactions of 1,3-Dipoles with Heterocycles, 9. - Reactions of Nitrilimines with Pyrazines, Pyrimidines and 1H-PyrimidinethionesAnalogous to the synthesis of 1,3-diaryl-1,8a-dihydro-1,2,4-triazolo[4,3-a]pyridines by 1,3-dipolar cycloaddition of diarylnitrilimines with pyridines, the C=N bonds of pyrazine and pyrimidine regio- and stereoselectively react as heterodipolarophiles with nitrilimines 2, generated in situ by dehydrohalogenation of corresponding hydrazonoyl chlorides 1. Whereas in the reaction with pyrazine the biscycloadducts 1,10,10a,10b-tetrahydrodi[1,2,4]triazolo[4,3-a:3′,4′-c] pyrazines 4 were obtained, the interaction of 2 with pyrimidines gave rise to stable monocycloadducts 5, 6 and 7 (1,8a-dihydro-1,2,4-triazolo[4,3-a]pyrimidines). Furthermore a study of the cycloaddition behaviour of a series of pyrimidine-2(1H)-thiones and -4(1H)-thiones with nitrilimines has been carried out. From the different kinds of potentially reactive sites under normal reaction conditions exclusively the semicyclic C=S bond of pyrimidinethiones shows a cycloaddition reaction to give the corresponding spiro[pyrimidine-4(1H),2′(3′H)-[1,3,4]thiadiazoles] 8 and 9. Using a large excess of nitrilimine in the cycloaddition with pyrimidine-2(1H)-thiones 2:1-cycloadducts 10 were formed.
Additional Material:
2 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.199419941009
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