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Abstract The synthesis and characterization of (tBuPBP)Ni(OAc) (5) by insertion of carbon dioxide into the Ni−C bond of (tBuPBP)NiMe (1) is presented. An unexpected CO2cleavage process involving the formation of new B−O and Ni−CO bonds leads to the generation of a butterfly‐structured tetra‐nickel cluster (tBuPBOP)2Ni4(μ‐CO)2(6). Mechanistic investigation of this reaction indicates a reductive scission of CO2by O‐atom transfer to the boron atom via a cooperative nickel‐boron mechanism. The CO2activation reaction produces a three‐coordinate (tBuP2BO)Ni‐acyl intermediate (A) that leads to a (tBuP2BO)−NiIcomplex (B) via a likely radical pathway. The NiIspecies is trapped by treatment with the radical trap (2,2,6,6‐tetramethylpiperidin‐1‐yl)oxyl (TEMPO) to give (tBuP2BO)NiII(η2‐TEMPO) (7). Additionally,13C and1H NMR spectroscopy analysis using13C‐enriched CO2provides information about the species involved in the CO2activation process.
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Catalytic enantioselective reductive domino alkyl arylation of acrylates via nickel/photoredox catalysis
Abstract Nonsteroidal anti-inflammatory drug derivatives (NSAIDs) are an important class of medications. Here we show a visible-light-promoted photoredox/nickel catalyzed approach to construct enantioenriched NSAIDs via a three-component alkyl arylation of acrylates. This reductive cross-electrophile coupling avoids preformed organometallic reagents and replaces stoichiometric metal reductants by an organic reductant (Hantzsch ester). A broad range of functional groups are well-tolerated under mild conditions with high enantioselectivities (up to 93% ee) and good yields (up to 90%). A study of the reaction mechanism, as well as literature precedence, enabled a working reaction mechanism to be presented. Key steps include a reduction of the alkyl bromide to the radical, Giese addition of the alkyl radical to the acrylate and capture of the α-carbonyl radical by the enantioenriched nickel catalyst. Reductive elimination from the proposed Ni(III) intermediate generates the product and forms Ni(I).
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- Award ID(s):
- 1902509
- PAR ID:
- 10348045
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 12
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1038/s41467-021-26794-8
