N‐Sulfonylcarboxamide as an Oxidizing Directing Group for Ruthenium‐Catalyzed C–H Activation/Annulation

Abstract

N‐Sulfonylcarboxamides can act as both a directing group for C–H activation and an internal oxidant in the Ru‐catalyzed annulation reaction with alkynes to give isoquinolones. Of all of the N‐sulfonylcarboxamides that were studied, the N‐(2,6‐difluorophenyl)sulfonamide derivatives were found to be the most efficient and led to the formation of an unstable sulfinate byproduct that decomposed into 1,3‐difluorobenzene under the reaction conditions. The described isoquinolone synthesis provides an alternative to the currently known traceless annulations of hydroxamic acid and sulfoximine derivatives.

Expeditious Synthesis of Isoquinolone Derivatives by Rhodium(I)-Catalyzed Annulation Reaction through C–C Bond Cleavage

“…Compounds containing the isoquinolone skeleton are famous for their antitumor, antiallergic, and antipsychotic activities . Consequently, great efforts of synthetic chemists have been devoted to establishing some efficient procedures for the preparation of isoquinolone derivatives in recent years. − Among these, the most amazing and popular strategy is the transition-metal-catalyzed oxidative annulation of benzamide derivatives with alkynes through C–H/N–H dual activation. , Several hypervalent transition-metal catalysts, such as Rh III , Ru II , Co III , Pd II , and Fe III , can be employed in this transformation (Figure ). Despite considerable advantages, these reactions usually require stoichiometric amounts of external or internal oxidants, and substituent groups on the nitrogen atoms of products are restricted because of the limitation of amides as directing groups in the transformation.…”

Reaching Green: Heterocycle Synthesis by Transition Metal‐Catalyzed C−H Functionalization in Sustainable Medium

“…In this reaction, benzamides with electronegative atoms like oxygen or bromine at meta position predominantly underwent C−H activation at the highly hindered position. As N−O bond, N−S bond could also be acted as internal oxidant as demonstrated by Jirgensons et al …”

The Role of Sulphonamides and N‐Sulphonyl Ketimines/Aldimines as Directing Groups in the Field of C−H Activation

“…Jirgensons and his group [54] explored the synthesis of isoquinolones through C−H activation/ annulation by employing Ru as catalyst. The team evidenced the ability of various N ‐sulphonyl carboxamides to act as directing group and internal oxidant for cleavage of N−S bond.…”