Nitrobenzo thiophene dioxide

IR spectroscopy has been used to show that 2-aminobenzo[6]thio-phenes normally exist solely as the amino tautomer,112-114 and that 2 ii2,ii3 an(j 3-hydroxybenzo[6]thiophenes117,147 exist solely as the keto tautomers, except that compounds with an adjacent carbonyl-containing group exist mainly as the enols.109,116,147> 148 3-Hydroxy-2-nitrobenzo[6]thiophene-l,1-dioxide exists as a mixture of the keto and enol forms.149... 

V-Substituted 3-aminobenzo[6]thiophenes are readily obtained by heating thioindoxyl with the appropriate primary or secondary aromatic amine,539 541,553,554 or primary aliphatic amine541 (Section VI, 1,2). 3-A7,jV-I)ialkylaminobemo[ ]thiophenes are best obtained by reaction of 3-bromobenzo[6]thiophene-1,1 -dioxide with a secondary aliphatic amine, followed by reduction of the product with lithium aluminum hydride (Section VI,P,2,/).541 3-Amino-2-nitrobenzo[6]-thiophene and its A-substituted derivatives are conveniently obtained... 

Cleavage of the hetero ring of 3-nitrobenzo[A]thiophene is the first step in a synthesis of ( )-2-aryl-l-[2-(methylsul-fonyl)phenyl]-l-nitroethenes (Scheme 176). The sulfonyl-stabilized anion derived from these alkenes by metallation adds in Michael fashion to the nitrovinyl unit to form 4-nitrothiochroman 1,1-dioxides as an inseparable mixture of two diastereomers. The overall process corresponds to expansion of a thiophene ring to a thiopyran unit <2004T4967>. 

Scheme 72 Dimerization of 4-nitrobenzo[i)]thiophene 1,1-dioxide and 5-bromobenzo[6]thio-phene 1,1-dioxide [95]...

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