Huiling Jiang

Chemoselective Amination of Propargylic C(sp3)H Bonds by Cobalt(II)‐Based Metalloradical Catalysis

Highly chemoselective intramolecular amination of propargylic C(sp(3))-H bonds has been demonstrated for N-bishomopropargylic sulfamoyl azides through cobalt(II)-based metalloradical catalysis. Supported by D(2h)-symmetric amidoporphyrin ligand 3,5-Di(t)Bu-IbuPhyrin, the cobalt(II)-catalyzed C-H amination proceeds effectively under neutral and nonoxidative conditions without the need of any additives, and generates N2 as the only byproduct. The metalloradical amination is suitable for both secondary and tertiary propargylic C-H substrates with an unusually high degree of functional-group tolerance, thus providing a direct method for high-yielding synthesis of functionalized propargylamine derivatives.

Stereoselective radical amination of electron-deficient C(sp3)-H bonds by Co(II)-based metalloradical catalysis: direct synthesis of α-amino acid derivatives via α-C-H amination.

The cobalt(II) complex of 3,5-Di(t)Bu-IbuPhyrin, [Co(P1)], is an effective catalyst for intramolecular amination of electron-deficient C-H bonds, including those adjacent to electron-withdrawing CO(2)R, C(O)NR(2), C(O)R, and CN groups, in excellent yields with high regio- and stereoselectivity. The [Co(P1)]-catalyzed amination system provides a direct method for the synthesis of α-amino acid derivatives from the corresponding carboxylate precursors.

Chemoselective intramolecular allylic C–H aminationversus CC aziridination through Co(II)-based metalloradical catalysis

Excellent chemoselectivity for intramolecular allylic C–H aminationversus CC aziridination was achieved through Co(II)-based metalloradical catalysis. Metalloradical catalyst [Co(P1)], the cobalt(II) complex of D2h-symmetric porphyrin 3,5-DitBu-IbuPhyrin, was shown to be highly effective for selective intramolecular allylic C–H amination of both N-bishomoallylic and N-allylic sulfamoyl azides. The Co(II)-catalyzed intramolecular 1,6-C–H amination of these azides provides a general and efficient method to access the synthetically useful allylic 1,3-diamines under neutral and non-oxidative conditions, without complication from the competitive olefin aziridination. The origin of this remarkable chemoselectivity has direct relevance to the radical mechanism of Co(II)-based metalloradical amination.

Intramolecular 1,5-C(sp3)–H radical amination via Co(II)-based metalloradical catalysis for five-membered cyclic sulfamides

Synthesis of strained five-membered cyclic sulfamides has been achieved for the first time by intramolecular 1,5-C(sp3)–H amination via Co(ii)-based metalloradical catalysis.

Intramolecular Radical Aziridination of Allylic Sulfamoyl Azides by Cobalt(II)-Based Metalloradical Catalysis: Effective Construction of Strained Heterobicyclic Structures

Cobalt(II)-based metalloradical catalysis (MRC) has been successfully applied for effective construction of the highly strained 2-sulfonyl-1,3-diazabicyclo[3.1.0]hexane structures in high yields through intramolecular radical aziridination of allylic sulfamoyl azides. The resulting [3.1.0] bicyclic aziridines prove to be versatile synthons for the preparation of a diverse range of 1,2- and 1,3-diamine derivatives by selective ring-opening reactions. As a demonstration of its application for target synthesis, the metalloradical intramolecular aziridination reaction has been incorporated as a key step for efficient synthesis of a potent neurokinin 1 (NK1 ) antagonist in 60 % overall yield.

Asymmetric Radical Bicyclization of Allyl Azidoformates via Cobalt(II)-Based Metalloradical Catalysis

Cobalt(II)-based metalloradical catalysis has been successfully applied to radical bicyclization of allyl azidoformates to construct aziridine/oxazolidinone-fused bicyclic structures. The Co(II) complex of D2-symmetric chiral amidoporphyrin 3,5-DitBu-QingPhyrin has been identified as an effective metalloradical catalyst for the intramolecular radical aziridination of this type of carbonyl azides, allowing for high-yielding formation of synthetically useful chiral [3.1.0]-bicyclic aziridines with high diastereo- and enantioselectivity.