Spirocyclic Sultam and Heterobiaryl Synthesis through Rh-Catalyzed Cross-Dehydrogenative Coupling of N-Sulfonyl Ketimines and Thiophenes or Furans

Abstract

A useful approach is developed for the synthesis of various structurally interesting spirocyclic sultams and heterobiaryls using a cross-dehydrogenative coupling strategy that features high atom and step economy. This method employs [Cp*RhCl2]2 as a catalyst and N-sulfonylimine, a weak coordinating group, as an efficient directing group to assist C-H activation. A number of the coupled products were converted into interesting molecules through further synthetic transformations.

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

“…Wei et al., [70] disclosed spirocyclic sultams and heterobiaryls synthesis using sulphonyl imines as a directing group via C−H activation. Such C−H/C−H couplings were found to be rare in the reaction.…”

Transition‐Metal‐Catalyzed C−H Functionalization for Construction of Quaternary Carbon Centers

“…In addition to alkynes, dienes and alkenes can be also applied in the [3+2] annulations with cyclic N ‐sulfonyl ketimines to synthesize highly functionalized spirocycles, as reported by the groups of Nishimura and Li, respectively (Scheme , eqs 1 and 2). Interestingly, with a successive double C−H activation process, Wei and co‐workers reported the use of thiophenes as the C2 partner in the rhodium‐catalyzed [3+2] annulation with cyclic N ‐sulfonyl ketimines, which gives a rapid access to spirocyclic sultams 235 in good yields [Scheme , Eq. (3)].…”

Palladium‐Catalyzed ortho‐Heteroarylation of β‐Arylethylamines Through Cross‐Dehydrogenative Coupling

“…In 2013, You and co‐workers disclosed that the copper‐mediated rhodium‐catalyzed oxidative cross‐coupling of 2‐phenylpyridine and thiophene could proceed with high yields . The coupling reaction was applicable to various heteroarenes such as thiophenes, furans, thiazoles, oxazoles and xanthines . Since then, the ortho ‐selective ( o ‐selective) thiophenation of arenes via oxidative C–H/C–H cross‐coupling under the assistance of directing groups, such as pyridines and quinoline, thiazole and pyrimidines, amides, oxime ethers, azobenzenes and carboxylic acids, have been well explored in the last ten years, which greatly enriched the route to synthesize bi(hetero)aryls.…”