The reaction of 2-aminopyridines or 2-aminothiazole with N-(2,2-dichloro-2-phenylethylidene)arensulfonamides affords the corresponding products of nucleophilic addition to the azomethine group, N-[2,2-dichloro-2-phenyl-1-(heterylamino)ethyl]sulfonamides, in good yields. The latter are easily cyclized to (imidazo[1,2-a]pyridin-3-yl)sulfonamides and (imidazo[2,1-b]thiazol-5-yl)sulfonamides in the presence of [a] A.E. 369 Scheme 4. A tentative route for the formation of imidazo[1,2-a]pyridines 5.www.eurjoc.org
The reaction of 2‐aminopyrimidines with N‐(2,2‐dichloro‐2‐phenylethylidene)arenesulfonamides affords the corresponding products of nucleophilic addition to the azomethine group, N‐[2,2‐dichloro‐2‐phenyl‐1‐(heterylamino)ethyl]sulfonamides, in good yields. The latter are easily cyclized to give imidazo[1,2‐a]pyrimidin‐3‐ylsulfonamides in the presence of NaOH, whereas the expected isomeric imidazo[1,2‐a]pyrimidin‐2‐ylsulfonamides are not formed. A tentative mechanism for the formation of annulated heterocyclic derivatives through Dimroth rearrangement has been proposed.
N-(2,2-Dichloro-2-phenylethylidene)-4-chlorobenzenesulfonamide reacts with 2-aminothiazoles to give products of nucleophilic addition in good yields. The adducts are cyclized into the unexpected 5-(arylsulfonyl)amino-6-phenylimidazo[2,1-b]thiazoles in 70-75% yield; whereas the anticipated isomeric 6-(arylsulfonyl)amino-5-phenylimidazo[2,1-b]thiazoles were not observed.
An approach to the preparation of new polyhalogenated N-sulfonylsubstituted
azanorbornane derivatives, which are of interest as valuable reagents and promising biologically ac tive substances, has been demonstrated
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