Ligand-Controlled Cobalt-Catalyzed Regiodivergent Alkyne Hydroalkylation

Abstract

Regiodivergent alkyne hydroalkylation to generate different isomers of an alkene from the same alkyne starting material would be beneficial; however, it remains a challenge. Herein, we report a ligand-controlled cobalt-catalyzed regiodivergent alkyne hydroalkylation. The sensible selection of bisoxazoline (L1) and pyridine−oxazoline (L8) ligands led to reliable and predictable protocols that provided (E)-1,2-disubstituted and 1,1disubstituted alkenes with high E/Z stereoselectivity and regioisomeric ratio starting from identical terminal alkyne and alkyl halide substrates and produced trisubstituted alkenes in the case of internal alkynes. This method exhibits a broad scope for terminal and internal alkynes with a wide range of activated and unactivated alkyl halides and shows excellent functional group compatibility.

Cobalt-Catalyzed Multicomponent Carbonylation of Olefins: Efficient Synthesis of β-Perfluoroalkyl Imides, Amides, and Esters

“…Based on all of these mechanistic experiments and previous literature reports, we propose the following reaction pathway. As shown in Table E, this perfluoroalkylative carbonylation reaction likely starts with a reduction of Co­(acac) 2 using manganese as the reductant, generating a monovalent cobalt species LCo­(I) to initiate the catalytic cycle.…”

Regio- and Stereoselective Reductive Coupling of Alkynes and Crotononitrile

“…It should be noted that protolysis of II first generated an alkyl Co­(III) species followed by single electron reduction of this Co­(III) species to Co­(II) species, and further protolysis of Co­(II) species to give the desired product is also possible. In addition, we cannot exclude the pathway of cobalt hydride intermediate generated via proton reduction by DIPEA •+ or proton under the photoredox conditions, which can undergo selective hydrocobaltation of alkyne followed by carbocobaltation of crotononitrile affording the desired product. However, we prefer the cyclometalation pathway, which might be easier to control the stereoselectivities than the cobalt hydride pathway to access the stereodefined homoallylic nitrile product.…”

Origins of Regioselectivity in CuH-Catalyzed Hydrofunctionalization of Alkenes

“…The dissection of the activation energy of transition states can be effectively achieved by using the distortion/interaction-activation strain model and the approach of energy decomposition analysis (EDA) (Scheme c). Based on these two methods, the major factors affecting reactivity and selectivity in various types of organic reactions have been identified by the Bickelhaupt, Hamlin, and Fernández joint group, Houk, Liu, Hartwig, Fu, others, and us . In this work, with the assistance of EDA, we computationally analyze a series of hydrocupration transition states to identify the dominant factors controlling the regioselectivity for hydrofunctionalizations of both activated and unactivated olefins (Scheme c).…”