Regioselective Annulation of Aryl Sulfonamides with Allenes through Cobalt-Promoted C–H Functionalization

Abstract

The development of an efficient method for the construction of biologically relevant sultams is described, which represents the first case of cobalt-promoted C-H/N-H functionalization of sulfonamides with allenes. This newly developed annulation reaction demonstrated good functional group tolerance and excellent regioselectivity. Both terminal monosubstituted allenes and internal disubstituted allenes can be employed to give the desired sultams in good yields. This strategy can be successfully used to build a unique sultam library with novel structural diversity.

Sultams: Recent Syntheses and Applications

“…In a subsequent report Rao et al prepared a series of benzosultams 16.3 through regioselective annulation of N ‐quinolinyl arylsulfonamides 16.1 with allenes 16.2 through Co‐promoted C–H/N–H functionalization (Scheme ) . The annulations passed through a mechanistic pathway similar to that depicted in Scheme .…”

“…The ). [20] The annulations passed through a mechanistic pathway similar to that depicted in Scheme 15. Another subset of N-quinolinyl benzosultams 17.3 were prepared by Volla and co-workers by use of the same methodology of Co-catalyzed annulation of arylsulfonamides and allenes through C-H/N-H functionalizations (Scheme 17).…”

Cobalt‐Catalyzed Annulation Reactions via C−H Bond Activation

“…However, the conversion of isoquinolone with endo double bond to exo double bond did not occur in the presence of KOTf. Afterwards, Rao and Volla independently investigated the reactivity of 8‐aminoquinoline sulfonamide derivatives 123 with allenes 120 (Scheme ) and obtained the sultam products 124 with an endo double bond in good yields. It is noteworthy that in all cases insertion occurred at the least hindered terminal sp 2 carbon of allenes followed by reductive elimination and C−C double bond migration to give the cyclized products.…”

Iridium‐Catalyzed ortho‐C−H Amidation of Benzenesulfonamides with Sulfonyl Azides

“…[20] Later, Ribas and Rao developed a Co-catalyzed CÀ H/NÀ H functionalization of aryl sulfonamides with alkynes and allenes, respectively. [21] In 2016, our group developed an efficient synthetic route to access biaryl sulfonamide derivatives via Pd-catalyzed CÀ H arylation of benzenesulfonamides by employing an amino acid moiety as the bidentate directing group. [22] Recently, You reported an alternative method for synthesis of biaryl sulfonamide via Rh-catalyzed oxidative CÀ H/CÀ H cross-coupling of aromatic sulfonamides with arenes.…”