Enantioselective Synthesis of trans -2,3-Dihydro-1H -indoles Through C-H Insertion of α-Diazocarbonyl Compounds

Ruthenium-Catalyzed Enantioselective C-H Functionalization: A Practical Access to Optically Active Indoline Derivatives

Ru(II)-catalyzed enantioselective C-H activation/hydroarylation has been developed for the first time, allowing for highly enantioselective synthesis of indoline derivatives via catalytic C-H activation. Commercially available Ru(II) arene complexes and chiral α-methylamines were employed as highly enantioselective catalysts. Based on a sterically rigidified chiral transient directing group, multisubstituted indolines were produced in up to 92% yield with 96% ee. Further transformation of the resulting 4-formylindoline enables access to an optically active tricyclic compound that is of potential biological and pharmaceutical interest.

Enantioselective Synthesis of Indolines, Benzodihydrothiophenes, and Indanes by C-H Insertion of Donor/Donor Carbenes

We employ a single catalyst/oxidant system to enable the asymmetric syntheses of indolines, benzodihydrothiophenes, and indanes by C-H insertion of donor/donor carbenes. This methodology enables the rapid construction of densely substituted five-membered rings that form the core of many drug targets and natural products. Furthermore, oxidation of hydrazones to the corresponding diazo compounds proceeds in situ, enabling a relatively facile one- or two-pot protocol in which isolation of potentially explosive diazo alkanes is avoided. Regioselectivity studies were performed to determine the impact of sterics and electronics in donor/donor metal carbene C-H insertions to form indolines. This methodology was applied to a variety of substrates in high yield, diastereomeric, and enantiomeric ratios and to the synthesis of a patented indane estrogen receptor agonist with anti-cancer activity.

Enantioselective radical process for synthesis of chiral indolines by metalloradical alkylation of diverse C(sp3)-H bonds

A new C–C bond formation strategy based on enantioselective radical alkylation of C(sp³)–H bonds via Co(ii)-based metalloradical catalysis has been demonstrated for stereoselective synthesis of chiral indolines.

A new C–C bond formation strategy based on enantioselective radical alkylation of C(sp³)–H bonds via Co(ii)-based metalloradical catalysis has been demonstrated for stereoselective synthesis of chiral indolines. The Co(ii)-based system enables activation of aryldiazomethanes as radical precursors at room temperature for enantioselective intramolecular radical alkylation of broad types of C–H bonds, constructing 2-substituted indolines in high yields with excellent enantioselectivities. In addition to chemoselectivity and regioselectivity, this Co(ii)-catalyzed alkylation features tolerance to functional groups and compatibility with heteroaryl substrates. Detailed mechanistic studies provide insight into the underlying stepwise radical pathway.