The cross-coupling of sp3-hybridized organoboron reagents via photoredox/nickel dual catalysis represents a new paradigm of reactivity for engaging alkylmetallic reagents in transition-metal-catalyzed processes. Reported here is an investigation into the mechanistic details of this important transformation using density functional theory. Calculations bring to light a new reaction pathway involving an alkylnickel(I) complex generated by addition of an alkyl radical to Ni(0) that is likely to operate simultaneously with the previously proposed mechanism. Analysis of the enantioselective variant of the transformation reveals an unexpected manifold for stereoinduction involving dynamic kinetic resolution (DKR) of a Ni(III) intermediate wherein the stereodetermining step is reductive elimination. Furthermore, calculations suggest that the DKR-based stereoinduction manifold may be responsible for stereoselectivity observed in numerous other stereoconvergent Ni-catalyzed cross-couplings and reductive couplings.

Desymmetrization of various meso-methylenecyclopropanes was accomplished by a palladium-catalyzed asymmetric ring-opening bis(alkoxycarbonylation) reaction employing a chiral bioxazoline ligand. The reaction proceeded smoothly in the presence of copper(I) triflate under carbon monoxide and oxygen at ambient pressure to give the corresponding optically active α-methyleneglutarates with up to 60% ee. Desymmetrization of protected meso-(3-methylenecyclopropane-1,2-diyl)dimethanols was also carried out to give enantioenriched highly oxygen-functionalized α-methyleneglutarates.(S,S)-4,4′-Bis(1-naphthalenylmethyl)-4,4′,5,5′-tetrahydro-2,2′-bioxazoleC28H24N2O2Ee = 100%[α]D25 = −5 (c 0.9, CHCl3)Source of chirality: (S)-2-amino-3-(1-naphthalenyl)-1-propanolAbsolute configuration: (S,S)(R,R)-4,4′-Bis(2-naphthalenylmethyl)-4,4′,5,5′-tetrahydro-2,2′-bioxazoleC28H24N2O2Ee = 100%[α]D25 = −26 (c 0.3, CHCl3)Source of chirality: (R)-2-amino-3-(2-naphthaleny)-1-propanolAbsolute configuration: (R,R)(1R,2S)-Methyl 2-(3-methoxy-3-oxo-1-propen-2-yl)cyclohexanecarboxylateC12H18O4Ee = 60%[α]D25 = −49 (c 0.6, EtOH)Source of chirality: asymmetric ring-opening bis(alkoxycarbonylation) reactionAbsolute configuration: (1R,2S)(1R,2S)-Methyl 2-(3-methoxy-3-oxo-1-propen-2-yl)cyclooctanecarboxylateC14H22O4Ee = 45%[α]D25 = −11 (c 0.1, EtOH)Source of chirality: asymmetric ring-opening bis(alkoxycarbonylation) reactionAbsolute configuration: (1R,2S)(2S,3S)-Dimethyl 2,3-bis((benzyloxy)methyl)-4-methylenepentanedioateC24H28O6Ee = 28%[α]D25 = +6 (c 1.3, EtOH)Source of chirality: asymmetric ring-opening bis(alkoxycarbonylation) reactionAbsolute configuration: (2S,3S)(3S,4S)-Dimethyl 2-methylene-3,4-bis((trityloxy)methyl)pentanedioateC48H44O6Ee = 42%[α]D25 = +5 (c 0.5, EtOH)Source of chirality: asymmetric ring-opening bis(alkoxycarbonylation) reactionAbsolute configuration: (3S,4S)(3S,4S)-Dimethyl 2-methylene-3,4-bis((triphenylsilyloxy)methyl)pentanedioateC46H44O6Si2Ee = 48%[α]D25 = +6 (c 1.5, CHCl3)Source of chirality: asymmetric ring-opening bis(alkoxycarbonylation) reactionAbsolute configuration: (3S,4S)(2S,3S)-Dimethyl 2,3-bis((tert-butyldiphenylsilyloxy)methyl)-4-methylenepentanedioateC42H52O6Si2Ee = 51%[α]D25 = +3 (c 1.9, EtOH)Source of chirality: asymmetric ring-opening bis(alkoxycarbonylation) reactionAbsolute configuration: (2S,3S)(1S,4R)-2-((1S,2R)-2-((((1S,4R)-4,7,7-trimethyl-3-oxo-2-oxabicyclo[2.2.1]heptane-1-carbonyl)oxy)methyl)cyclohexyl)allyl 4,7,7-trimethyl-3-oxo-2-oxabicyclo[2.2.1]heptane-1-carboxylateC30H42O8Ee = 100%[α]D25 = −11 (c 0.1, EtOH)Source of chirality: asymmetric ring-opening bis(alkoxycarbonylation) reactionAbsolute configuration: (1S,4R),(1S,2R),(1S,4R)