Reaction of sulfene with heterocyclic N,N‐disubstituted α‐aminomethyleneketones. VIII. Synthesis of furo[2,3‐h]‐1,2‐benzoxathiin derivatives

Abstract

Cycloaddition of sulfene to N,N‐disubstituted (E)5‐aminomethylene‐6,7‐dihydrobenzo[b]furan‐4(5H)ones I gave, only in the case of aliphatic N‐substitution and generally in satisfactory yields, N,N‐disubstituted 4‐amino‐3,4,5,6‐tetrahydrofuro[2,3‐h]‐1,2‐benzoxathiin 2,2‐dioxides II, which are derivatives of the new heterocyclic system furo[2,3‐h]‐1,2‐benzoxathiin. The 4‐dimethylamino and 4‐piperidino cycloadducts IIa,e were dehydrogenated with DDQ to the corresponding 4‐dialkylamino‐3,4‐dihydrofuro[2,3‐h]‐1,2‐benzoxathiin 2,2‐dioxides IIIa,e in low yield. Compounds IIIa,e were tested for photobiological activity and found to be inactive.

Expedient synthesis of highly substituted 3,4-dihydro-1,2-oxathiine 2,2-dioxides and 1,2-oxathiine 2,2-dioxides: revisiting sulfene additions to enaminoketones

“…25 In the foregoing study the authors noted the variably of their DDQ aromatization protocol which failed to dehydrogenate the 1,2-oxathiine ring of the furan analogue 4 X = O and instead gave 6. 26 We have previously examined the synthesis of a novel dithienylethene photochromic system in which the ethene bridge forms part of a 1,2-oxathiine 2,2-dioxide ring. 27 In the latter work the…”