Chiral Osmium(II)/Salox Species Enabled Enantioselective γ-C(sp3)-H Amidation: Integrated Experimental and Computational Validation For the Ligand Design and Reaction Development.

Herein, multiple types of chiral Os(II) complexes have been designed to address the appealing yet challenging asymmetric C(sp3)-H functionalization, among which the Os(II)/Salox species is found to be the most efficient for precise stereocontrol in realizing the asymmetric C(sp3)-H amidation. As exemplified by the enantioenriched pyrrolidinone synthesis, such tailored Os(II)/Salox catalyst efficiently enables an intramolecular site-/enantioselective C(sp3)-H amidation in the γ-position of dioxazolone substrates, in which benzyl, propargyl and allyl groups bearing various substituted forms are well compatible, affording the corresponding chiral γ-lactam products with good er values (up to 99 : 1) and diverse functionality (>35 examples). The unique performance advantage of the developed chiral Os(II)/Salox system in terms of the catalytic energy profile and the chiral induction has been further clarified by integrated experimental and computational studies.

Rh(III)-Catalyzed Redox-Neutral C-H Activation/[3 + 2] Annulation of N-Phenoxy Amides with Propargylic Monofluoroalkynes.

An efficient and redox-neutral Rh(III)-catalyzed C-H activation/[3 + 2] annulation of N-phenoxy amides with propargylic monofluoroalkynes has been realized to afford 3-alkylidene dihydrobenzofurans with an interesting α-quaternary carbon center. Combined experimental and computational mechanistic studies revealed that a Rh(III)-Rh(V)-Rh(III) catalytic pathway/uncatalyzed intramolecular [H···F] bonding-assisted SN2'-type substitution cascade might be involved in the catalytic cycle, thereby enabling an excellent site-/regioselectivity with broad substrate/functional group compatibility, including the complete retention of the highly strained cyclobutyl structure in the 3-position.

Rh(III)-Catalyzed C-H Activation/Cycloisomerization of N-Phenoxyacetamides with Enynones for One-Pot Assembly of Furylated 2-Alkenylphenols.

An efficient and practical procedure for one-pot assembly of furylated 2-alkenylphenols has been achieved via the Cp*CyRh-catalyzed regioselective redox-neutral C-H activation/5-exo-dig cyclization cascade using N-phenoxyacetamides and enynones as the viable substrates. The synthetic application of such a protocol has also been demonstrated to highlight the versatility of this transformation.