Computational study of catalyst-controlled regiodivergent pathways in hydroboration of 1,3-dienes: mechanism and origin of regioselectivity

Fu, Zhongxin; Guo, Xianming; Li, Yupan; Li, Juan

doi:10.1039/d0qo00479k

Cited by 13 publications

(8 citation statements)

References 81 publications

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“…The wide spread use of this functional in exploring various catalytic mechanisms have prompted us to select this functional. [37][38][39][40][41] Single point calculations were performed using M06-2X, which is a highly parametrized functional known to give good performance for main group thermochemistry, kinetics and non-covalent interactions along with a correlationconsistent basis set. 42 Regio-and stereoselectivity of the reaction were studied by employing propyne (MeCCH).…”

Section: Methodsmentioning

confidence: 99%

“…Initial characterizations were done using B3LYP, a popular hybrid GGA functional. The wide spread use of this functional in exploring various catalytic mechanisms have prompted us to select this functional 37–41 . Single point calculations were performed using M06‐2X, which is a highly parametrized functional known to give good performance for main group thermochemistry, kinetics and non‐covalent interactions along with a correlation‐consistent basis set 42 .…”

Section: Methodsmentioning

confidence: 99%

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Computationally unraveling the mechanism and selectivity of five and six membered N‐heterocyclic carbene‐catalyzed alkyne hydrochalcogenation

Jayasree

Reshma

Aswathy

2021

Int J of Quantum Chemistry

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The present work is intended to bring to the forefront a relatively less explored area of N-Heterocyclic Carbene (NHC) catalyzed alkyne hydro-thiolation and selenation reactions by exploring the reaction mechanism. Reaction mechanism involves chalcogenol activation followed by alkyne insertion and the second step is the rate determining step. A comparison with the reported uncatalyzed gas phase reaction showed that a simple imidazol-2-ylidene catalyst can lower the free energy barrier by 28.74 and 21.73 kcal/mol respectively for acetylene hydro-thiolation and selenation reaction. All the employed NHCs are proved to be better catalyst for both hydrothiolation and hydroselenation. Factors such as changing the heterocycle, increasing the conjugation, ring expansion and electronic/steric substitution at the heteroatom were found to affect the energy barriers due to the geometric variations at NHCcarbon and S/Se in the intermediate and the transition structure corresponding to alkyne insertion. Effect of solvent polarity on the reaction energetics and selectivity has also been analyzed employing THF, DMSO and MeOH as the solvents.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Computationally unraveling the mechanism and selectivity of five and six membered N‐heterocyclic carbene‐catalyzed alkyne hydrochalcogenation

Jayasree

Reshma

Aswathy

2021

Int J of Quantum Chemistry

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“…The wide spread use of this functional in exploring various catalytic mechanisms have prompted us to select this functional. [37][38][39][40][41] Single point calculations were performed using M06-2X, which is a highly parametrized functional known to give good performance for main group thermochemistry, kinetics and non-covalent interactions along with a correlation-consistent basis set. 42 Regio-and stereoselectivity of the reaction were studied by employing propyne (MeCCH).…”

Section: Methodsmentioning

confidence: 99%

Computationally Unravelling the Mechanism and Selectivity of Five and Six membered N-Heterocyclic Carbene- Catalyzed Alkyne Hydrochalcogenation

Elambalassery¹,

Reshma²,

Aswathy³

2020

Preprint

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The present work is intended to bring to the forefront a relatively less explored area of N-Heterocyclic Carbene (NHC) catalyzed alkyne hydro- thiolation and selenation reactions. The present work can be regarded as the first ever computational investigation on the catalytic activity of the NHC catalyzed hydro- thiolation and selenation reactions by exploring the reaction mechanism. Reaction mechanism involves chalcogenol activation followed by alkyne insertion and the second step is found to be the rate determining step. A comparison with the reported uncatalyzed gas phase reaction showed that a simple imidazol-2-ylidene catalyst can lower the free energy barrier by 19.62 and 14.63 kcal/mol respectively for acetylene hydro- thiolation and selenation reaction. All the employed NHCs are proved to be better catalyst for both hydrothiolation and hydroselenation. Effects of factors such as changing the heterocycle, increasing the conjugation, ring expansion and electronic/steric substitution were also investigated. Effect of solvent polarity on the reaction energetics and selectivity has also been analyzed employing THF, DMSO and MeOH as the solvents.

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“…In 2017 when we first disclosed the Co-catalyzed enantioselective hydroboration of prochiral acyclic 1,3-dienes, there were no reports of such a reaction among this class of compounds . Shortly thereafter, Mazet published a Cu-catalyzed addition of bispinacolborane in protic solvents to get high enantioselectivity for the 1,2-hydroboration products from prochiral 1,3-dienes, and this area has since received much attention . Our work started with the assumption that the cationic Co(I) catalysts would also be effective for the regio- and enantioselective hydroboration of 1,3-dienes.…”

Section: Regio- and Enantioselective Hydroboration Of 13-dienesmentioning

confidence: 99%

A New Paradigm in Enantioselective Cobalt Catalysis: Cationic Cobalt(I) Catalysts for Heterodimerization, Cycloaddition, and Hydrofunctionalization Reactions of Olefins

et al. 2021

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Conspectus One of the major challenges facing organic synthesis in the 21st century is the utilization of abundantly available feedstock chemicals for fine chemical synthesis. Regio- and enantioselective union of easily accessible 1,3-dienes and other feedstocks like ethylene, alkyl acrylates, and aldehydes can provide valuable building blocks adorned with latent functionalities for further synthetic elaboration. Through an approach that relies on mechanistic insights and systematic examination of ligand and counterion effects, we developed an efficient cobalt-based catalytic system [(P∼P)CoX2/Me3Al] (P∼P = bisphosphine) to effect the first enantioselective heterodimerization of several types of 1,3-dienes with ethylene. In addition to simple cyclic and acyclic dienes, siloxy-1,3-dienes participate in this reaction, giving highly functionalized, nearly enantiopure silyl enolates, which can be used for subsequent C–C and C–X bond-forming reactions. As our understanding of the mechanism of this reaction improved, our attention was drawn to more challenging partners like alkyl acrylates (one of the largest volume feedstocks) as the olefin partners instead of ethylene. Prompted by the intrinsic limitations of using aluminum alkyls as the activators for this reaction, we explored the fundamental chemistry of the lesser known (P∼P)Co(I)X species and discovered that in the presence of halide sequestering agents, such as sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBARF) or (C6F5)3B, certain chiral bisphosphine complexes are superb catalysts for regio- and enantioselective heterodimerization of 1,3-dienes and alkyl acrylates. We have since found that these cationic Co(I) catalysts, most conveniently prepared in situ by reduction of the corresponding cobalt(II) halide complexes by zinc in the presence of NaBARF, promote enantioselective [2 + 2]-cycloaddition between alkynes and an astonishing variety of alkenyl derivatives to give highly functionalized cyclobutenes. In reactions between 1,3-enynes and ethylene, the [2 + 2]-cycloaddition between the alkyne and ethylene is followed by a 1,4-addition of ethylene in a tandem fashion to give nearly enantiopure cyclobutanes with an all-carbon quaternary center, giving a set of molecules that maps well into many medicinally relevant compounds. In another application, we find that the cationic Co(I)-catalysts promote highly selective hydroacylation and 1,2-hydroboration of prochiral 1,3-dienes. Further, we find that a cationic Co(I)-catalyst promotes cycloisomerization followed by hydroalkenylation of 1,6-enynes to produce highly functionalized carbo- and heterocyclic compounds. Surprisingly the regioselectivity of the alkene addition depends on whether it is a simple alkene or an acrylate, and the acrylate addition produces an uncommon Z-adduct. This Account will provide a summary of the enabling basic discoveries and the attendant developments that led to the unique cationic Co(I)-complexes as catalysts for disparate C–C and C–B bond-forming reactions. It...

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Computational study of catalyst-controlled regiodivergent pathways in hydroboration of 1,3-dienes: mechanism and origin of regioselectivity

Abstract: DFT calculations were performed to elucidate the origins of catalyst-controlled regioselectivity in the hydroboration of 2-substituted 1,3-dienes.

Cited by 13 publications

References 81 publications

Computationally unraveling the mechanism and selectivity of five and six membered N‐heterocyclic carbene‐catalyzed alkyne hydrochalcogenation

Computationally unraveling the mechanism and selectivity of five and six membered N‐heterocyclic carbene‐catalyzed alkyne hydrochalcogenation

Computationally Unravelling the Mechanism and Selectivity of Five and Six membered N-Heterocyclic Carbene- Catalyzed Alkyne Hydrochalcogenation

A New Paradigm in Enantioselective Cobalt Catalysis: Cationic Cobalt(I) Catalysts for Heterodimerization, Cycloaddition, and Hydrofunctionalization Reactions of Olefins

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