The Ugi four-component condensation between cycloalkanones, isocyanides, and ammonium formate affords N-substituted 1-formylamino-1-cycloalkanecarboxamides 1 which are dehydrated to give the corresponding isocyanides 2. Compounds 2 are cyclized with arylsulfenyl thiocyanates to 1,3-diazaspiro-2-thiones 4 and 5. A series of 1,3-diazaspiro [4,5]dec-1-en-4-ones 7 is prepared by cyclizing 2c -1 with butyllithium.
The four‐component condensation between cycloketones 1, ammonium formate, and isocyanides 2 afforded formamides 3, which were dehydrated to the corresponding isocyanides 4. Upon treatment with n‐butyllithium, compounds 4 cyclized to spiroimidazolones 6, via the carbanions 5. A series of 2,3‐disubstituted spiroimidazolones 8 was obtained by reacting 5 with aldehydes 7.
The fragmentation patterns of aromatic Imethylisoxazolo-and Zmethyloxazolopyridines were investigated by high-resolution mass spectrometry and collisionally activated B/E and B'/E linked scalls The isoxamlopyridioes give mass spectra oear identical with those of the corresponding oxazolopyridines, both showing mainly a competitive loss of CO a d CH,CN from the molecular ion. However, the ratio of these concomitant pathways depeods substantially on the type of fusion between the five-and six-membered rings.
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