Palladium‐Catalyzed ortho‐Benzoylation of Sulfonamides through C−H Activation: Expedient Synthesis of Cyclic N‐Sulfonyl Ketimines

Abstract

The ortho-carbonylation of sulfonylarenes by non-hazardous aryl aldehydes as a carbonyl precursor was reported. In this method, the sulfonamide group serves as a directing group for CÀ H activation in the presence of a Pd catalyst under ligand-free conditions. The scope of this strategy has been extended to the onepot two-step synthesis of cyclic N-sulfonyl ketimines under mild reaction conditions. Our approach could be considered as an alternative by circumventing the use of highly reactive organolithium or Grignard reagents to access a wide range of biologically potent cyclic N-sulfonyl ketimines.

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

“…Panda and co‐workers [37] constructed carbonylated sulphonamides 40 and N ‐sulphonyl ketimines 41 which play significant role as synthons in heterocyclics and as chiral auxiliaries.…”

Aldehydes: magnificent acyl equivalents for direct acylation

“…In 2020, Panda and his group reported direct o-acylation of Nmethoxysulfonamides with aromatic aldehydes in the presence of Pd(OAc) 2 as catalyst and TBHP as oxidant. 60 In this transformation sulfonamide served as directing group. The scope of various N-methoxysulfonamides was investigated with aromatic aldehydes by synthesizing 22 o-acylated derivatives of N-methoxysulfonamides in 31-68% yields (Scheme 26A).…”

Pd(II)-Catalyzed C-H Acylation of (Hetero)arenes—Recent Advances

“…More recently, sulfonamides an N -sulfoximine amides have also been developed as directing groups ( Scheme 10 ). Sulfonamides 34 are acylated efficiently with aldehydes 5 in good yields in only 15 min [ 36 ]. Aliphatic aldehydes can also be used, although with lower yields.…”