Dual Cobalt/Organophotoredox Catalysis for Diastereo- and Regioselective 1,2-Difunctionalization of 1,3-Diene Surrogates Creating Quaternary Carbon Centers

Abstract

The synthesis of compounds having quaternary carbon centers through a catalytic stereo- and regioselective difunctionalization of 2-substituted 1,3-dienes remains elusive. Here, we present a dual Co/photoredox-catalyzed cascade approach that addresses this challenge using modular vinyl cyclic carbonates functioning as masked 2-aryl-1,3-diene surrogates. The latter species are conveniently prepared in situ and converted into nucleophilic Co­(allyl) intermediates that are intercepted by aldehydes to afford homoallylic alcohols with ample scope in reaction partners. The developed protocol marks a significant step forward in the use of structurally versatile 1,3-dienes and their catalytic 1,2-hydroalkylation and 1,2-dicarbofunctionalization.

Investigating Oxidative Addition Mechanisms of Allylic Electrophiles with Low-Valent Ni/Co Catalysts Using Electroanalytical and Data Science Techniques

“…Transition metal-catalyzed allylation-type reactions are a powerful method to construct new carbon–carbon and carbon–heteroatom bonds . This class of reactions spans from palladium-catalyzed Tsuji–Trost reactions (Scheme a) to more recent reductive allylation processes with first-row transition metals (Scheme b). − A common feature in all these transformations is the formation of a π-allyl-metal intermediate. Typically, a low-valent metal species undergoes oxidative addition across an allyl electrophile to generate a π-allyl-metal intermediate.…”

Decoding Key Transient Inter-Catalyst Interactions in a Reductive Metallaphotoredox-Catalyzed Allylation Reaction

“…Recently, our group and several others reported stereoselective cobalt-catalyzed allylation of aldehydes as a promising new way to synthesize highly functional compounds through C–C bond formation. − Such processes are mechanistically reminiscent to other important C–C bond-formation reactions in synthetic chemistry, for which metallaphotoredox catalysis recently demonstrated to be a powerful methodology. ,,− Here, we describe a detailed mechanistic analysis of a stereoselective C–C bond-formation reaction that can be considered as a representative example for various types of reductive dual metallaphotoredox catalytic C–C bond-formation reactions, and we give special attention to the inter-catalyst interactions (Figure b). Specifically, we elucidated the full mechanism of the allylation of aldehydes involving photoredox, cobalt, and base catalysis (Figure c).…”

Redox-neutral synthesis of π-allylcobalt complexes from alkenes for aldehyde allylation via photoredox catalysis

“…20,21 Most recently, the first photoredox and Co-catalyzed reductive carbonyl allylation was reported independently by Cozzi, Kleij, and our group. 22,23,[24][25][26] In particular, Kleij et al developed the elegant synthesis of syn-1,3-diols via Co/organophotoredox dual catalysis with extensive mechanism studies (Scheme 1a). [24][25][26] Additionally, Xia et al disclosed a photoredox/Co-catalyzed highly regio-and enantioselective reductive coupling of alkynes and aldehydes.…”

“…22,23,[24][25][26] In particular, Kleij et al developed the elegant synthesis of syn-1,3-diols via Co/organophotoredox dual catalysis with extensive mechanism studies (Scheme 1a). [24][25][26] Additionally, Xia et al disclosed a photoredox/Co-catalyzed highly regio-and enantioselective reductive coupling of alkynes and aldehydes. 27 Xiao et al reported an elegant photocatalytic Co-catalyzed asymmetric reductive Grignard-type addition of aryl iodides to aldehydes.…”