Reactions of pyridine analogues of aza-ortho-xylylenes generated from 1,3-dialkylpyridosultams

2,3-Dihydro-3-imino-2-methylenepyridines generated by thermal extrusion of SO2 from 1,3-dialkyl-1,3-dihydroisothiazolo[4,3-b]pyridine 2,2-dioxides (1, 3-dialkylpyridosultams), underwent [1,5] hydrogen shifts, which led to 3-al kylamino-2-vinylpyridine derivatives. Cycloalkanespiro-3-pyridosultams 12, which were easily obtained by alkylation of pyridosultams with alpha,omega- dihaloalkanes, gave, in a similar reaction, 3-alkylamino-2-cycloalkenylpyri dine derivatives 14 in good yields. Cyclobutanespiro-3-pyridosultam 12b, af ter thermal extrusion of SO2, formed cyclobutenyl derivative 14b, which und erwent a ring-opening reaction to form butadiene derivative 15. The latter can be trapped with dienophiles, for example, N-phenylmaleimide.