| Abstract
| - In prosecution of previous work on the thermal cyclization of 1-aryl-4-methanesulfonyl-2-nitro-3-phenylsulfonyl-1,3-butadienes (7), the 3-unsubstituted derivatives 8, deriving from the initial ringopening of 3-nitrothiophene (2), have been likewise found herein to undergo cyclization, followedby aromatization, in analogous mild experimental conditions, leading to the ring-fused homo- orheteroaromatic nitro derivatives 10. The concerted electrocyclic nature of the process is stronglysupported by the outcome of tests based on the variation of the polarity of the solvent or of theelectron density on the aryl of 8. Thus, the successful application of the process to thenon-phenylsulfonyl-activated 8 significantly widens the scope of a synthetically valuable overallring-opening/ring-closing procedure from nitrothiophenes. Support to the recently renewed interestin thermal 6π electrocyclizations as a tool for the construction of the benzene ring is furthermoreprovided.
|
