Synthetic Access to Hydrogen and Halogen Derivatives of 3‐Amino‐4‐nitrothiophenes

Abstract

The unique synthesis of 3‐amino‐4‐nitrothiophenes 2 provides easy access to reference species of a new family of push‐pull substituted thiophenes. The chemoselective modification of 2 into suitable derivatives was accomplished by selective S‐oxidation of the vinylsulfanyl unit, followed by substitution of the vinylsulfinyl group of 3 by nucleophiles. Dihalothiophenes were formed this way in very good yields. A subsequent selective dehalogenation at the 2, 5 or 2 and 5 positions also proved feasible, and the push‐pull unit was untouched. The new 2,5‐dihalothiophenes could be interesting monomers for conducting polymers.

Desulfurization of Diaryl(heteroaryl) Sulfoxides with Benzyne

“… As a continuation study of the aryne insertion chemistry, we report herein our discoveries of two new reactions between diaryl­(heteroaryl) sulfoxides ( 2 and 3 ) and benzyne (eqs 6 and 7, Scheme ). Unlike the reported cases (eqs –5), both reactions using benzyne as a reductant proceed through the desulfurization of the diaryl­(heteroaryl) sulfoxides and thus produce biaryls B2 or desulfurized heteroarenes C3 as the final products. The intriguing yet elusive differences among these two desulfurization reactions are also elucidated here by mechanistic studies.…”

Synthetic exploitation of halogenated alkenes containing EWG: benzotriazole-mediated synthesis of benzoazetines and thermal transformations

“…[3][4][5][6][7][8] The gem-dihalo nitrovinyl moiety also represents a very attractive key unit for syntheses of veand sixmembered heterocyclic compounds by selection of difunctional nucleophiles and other reagents. [9][10][11][12][13][14][15][16][17] The chemistry of benzo-condensed four-membered heterocyclic ring systems has been the focus of very little attention, mostly due to the instability of the series of their derivatives and complicated methods. Although o-xylylenes are versatile tools for the construction of these systems, 18 a traditional problem in the chemistry of o-xylylenes and their derivatives (oxy-, aza-, thio-) is the valence isomerization between the strained benzenoid form and the o-quinoidal form.…”