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Geminal cross couplings using multiple components enable the formation of several different bonds at one site in the building of tertiary and quaternary alkanes. Nevertheless, there are remaining issues of concern—cleavage of two geminal bonds and control of selectivity present challenges. We report here the geminal cross couplings of three components by reactions of dihaloalkanes with organomagnesium and chlorosilanes or alkyl tosylates by Cr catalysis, affording the formation of geminal C−C/C−Si or C−C/C−C bonds in the creation of tertiary and quaternary alkanes. The geminal couplings are catalyzed by low‐cost CrCl2, enabling the sluggishness of competitive Kumada‐type side couplings and homocouplings of Grignard reagents, in achieving high chemoselectivity. Experimental and theoretical studies indicate that two geminal C‐halide bonds are continuously cleaved by Cr to afford a metal carbene intermediate, which couples with a Grignard reagent, followed by silylation, in the formation of geminal C−C and C−Si bonds via a novel inner‐sphere radical coupling mechanism. These three‐component geminal cross couplings are value‐addition to the synthesis of commercial drugs and bioactive molecules in medicinal chemistry. [ABSTRACT FROM AUTHOR]

Geminal cross couplings using multiple components enable the formation of several different bonds at one site in the building of tertiary and quaternary alkanes. Nevertheless, there are remaining issues of concern—cleavage of two geminal bonds and control of selectivity present challenges. We report here the geminal cross couplings of three components by reactions of dihaloalkanes with organomagnesium and chlorosilanes or alkyl tosylates by Cr catalysis, affording the formation of geminal C−C/C−Si or C−C/C−C bonds in the creation of tertiary and quaternary alkanes. The geminal couplings are catalyzed by low‐cost CrCl2, enabling the sluggishness of competitive Kumada‐type side couplings and homocouplings of Grignard reagents, in achieving high chemoselectivity. Experimental and theoretical studies indicate that two geminal C‐halide bonds are continuously cleaved by Cr to afford a metal carbene intermediate, which couples with a Grignard reagent, followed by silylation, in the formation of geminal C−C and C−Si bonds via a novel inner‐sphere radical coupling mechanism. These three‐component geminal cross couplings are value‐addition to the synthesis of commercial drugs and bioactive molecules in medicinal chemistry. [ABSTRACT FROM AUTHOR]

A unique family of chiral peraza N6‐macrocyclic ligands, which are conformationally rigid and have a tunable saddle‐shaped cavity, is described. Utilizing their manganese(I) complexes, the first example of earth‐abundant transition metal‐catalyzed asymmetric formal anti‐Markovnikov hydroamination of allylic alcohols was realized, providing a practical access to synthetically important chiral γ‐amino alcohols in excellent yields and enantioselectivities (up to 99 % yield and 98 % ee). The single‐crystal structure of a MnI complex indicates that the manganese atom coordinates with the chiral dialkylamine moiety in a bidentate fashion. Further DFT calculations revealed that five of the six nitrogen atoms in the ligand were engaged in multiple noncovalent interactions with Mn, an isopropanol molecule, and a β‐amino ketone intermediate via coordination, hydrogen bonding, and/or CH⋅⋅⋅π interactions in the transition state, showing a remarkable role of the macrocyclic framework. [ABSTRACT FROM AUTHOR]

A unique family of chiral peraza N6‐macrocyclic ligands, which are conformationally rigid and have a tunable saddle‐shaped cavity, is described. Utilizing their manganese(I) complexes, the first example of earth‐abundant transition metal‐catalyzed asymmetric formal anti‐Markovnikov hydroamination of allylic alcohols was realized, providing a practical access to synthetically important chiral γ‐amino alcohols in excellent yields and enantioselectivities (up to 99 % yield and 98 % ee). The single‐crystal structure of a MnI complex indicates that the manganese atom coordinates with the chiral dialkylamine moiety in a bidentate fashion. Further DFT calculations revealed that five of the six nitrogen atoms in the ligand were engaged in multiple noncovalent interactions with Mn, an isopropanol molecule, and a β‐amino ketone intermediate via coordination, hydrogen bonding, and/or CH⋅⋅⋅π interactions in the transition state, showing a remarkable role of the macrocyclic framework. [ABSTRACT FROM AUTHOR]

Dearomative spirocyclization reactions represent a promising means to convert arenes into three‐dimensional architectures; however, controlling the regioselectivity of radical dearomatization with nonactivated arenes to afford the spirocyclizative 1,2‐difunctionalization other than its kinetically preferred 1,4‐difunctionalization is exceptionally challenging. Here we disclose a novel strategy for dearomative 1,2‐ or 1,4‐amidoximation of (hetero)arenes enabled by direct visible‐light‐induced homolysis of N−NO bonds of nitrosamides, giving rise to various highly regioselective amidoximated spirocycles that previously have been inaccessible or required elaborate synthetic efforts. The mechanism and origins of the observed regioselectivities were investigated by control experiments and density functional theory calculations. [ABSTRACT FROM AUTHOR]

Dearomative spirocyclization reactions represent a promising means to convert arenes into three‐dimensional architectures; however, controlling the regioselectivity of radical dearomatization with nonactivated arenes to afford the spirocyclizative 1,2‐difunctionalization other than its kinetically preferred 1,4‐difunctionalization is exceptionally challenging. Here we disclose a novel strategy for dearomative 1,2‐ or 1,4‐amidoximation of (hetero)arenes enabled by direct visible‐light‐induced homolysis of N−NO bonds of nitrosamides, giving rise to various highly regioselective amidoximated spirocycles that previously have been inaccessible or required elaborate synthetic efforts. The mechanism and origins of the observed regioselectivities were investigated by control experiments and density functional theory calculations. [ABSTRACT FROM AUTHOR]