A Mechanism Study for Self-Cleaving Chlorotetrafluoroethylsulfinyl (-SOCF2CF2Cl)-Directed Pd(II)-Catalyzed C-H Activation

A mechanism study for Pd(II)-catalyzed C(sp³)-H activation using a self-cleaving chlorotetrafluoroethylsulfinyl (-SOCF₂CF₂Cl) auxiliary as a directing group is reported. Mechanistic studies reveal that (1) the auxiliary group is crucial for C(sp³)-H activation, (2) the reaction undergoes a C(sp³)-H olefination-Michael addition-removal of the auxiliary sequence, (3) the removal of the auxiliary (SOR_f) is most likely the alcoholic solvolysis of the -SOCF₂CF₂Cl group on the N-tri-substituted sulfonamides, and (4) the C(sp³)-H cleavage is involved in the rate-determining step.

Synthesis of γ-Lactams via Pd(II)-Catalyzed C(sp3)-H Olefination Using a Self-Cleaving Polyfluoroethylsulfinyl Directing Group

A monodentate directing group, 2-chlorotetrafluoroethylsulfinylmide (-NHSOCF₂CF₂Cl), for inert C(sp³)-H bond activation is reported. This directing group shows efficient ability in Pd(II)-catalyzed C(sp³)-H olefination. The desired olefination products undergo subsequent Michael addition and in situ expulsion of the auxiliary to provide the free NH γ-lactam products. Preliminary mechanistic studies reveal that the auxiliary group is crucial for C(sp³)-H activation.

Synthesis of N-H-Free 1,4-Dihydroisoquinoline-3(2H)-ones via Pd-Catalyzed C-H Olefination Using Polyfluorosulfinyl as the Auxiliary Group

A Pd(II)-catalyzed olefination of aryl C-H bonds with a self-cleaving 2-chlorotretafluoroethylsulfinyl (-SOCF₂CF₂Cl) auxiliary was developed. In the reaction mixture, the olefination products underwent in situ Michael addition and the subsequent expulsion of the auxiliary to provide the N-H-free 1,4-dihydroisoquinoline-3(2H)-one products. Mechanistic studies reveal that the auxiliary group is crucial for C-H activation, and Na₂CO₃ and an alcoholic solvent play key roles in facilitating the cleavage of the polyfluoroalkylsulfinyl auxiliary.