Quantum mechanical calculations are employed to investigate the mechanism and origin of stereoinduction in asymmetric iron-catalyzed C(sp)-C(sp) cross-coupling reaction between Grignard reagents and α-chloroesters. A coherent mechanistic picture of this transformation is revealed. These results have broad implications for understanding the mechanisms of iron-catalyzed cross-coupling reactions and rational design of novel iron-based catalysts for asymmetric transformations.
A highly efficient method for the synthesis of α-hydroxy phosphonates via lanthanide amides [(Me(3)Si)(2)N](3)Ln(μ-Cl)Li(THF)(3) catalyzed hydrophosphonylation of aromatic aldehydes was developed. The reactions produced the products in excellent yields in the presence of 0.1 mol % [(Me(3)Si)(2)N](3)La(μ-Cl)Li(THF)(3) at room temperature within 5 min. The existence of LiCl in the catalyst was a key factor affecting the catalytic activity. The mechanism for the process of high efficiency was proposed.
Deoxygenative difunctionalization of carbonyls affords a straightforward and effective route to construct geminal dual functionalized motifs. However, the research in this field is very challenging due to the strong bond dissociation energies of the C−O double bond or the subsequently formed C−O bond. Herein, we report a highly efficient deoxygenative haloboration of aldehydes to generate secondary α-haloboronates. Meanwhile, the difficult-to-obtain tertiary α-haloboronates can be also readily prepared via the same strategy with ketones. Furthermore, enantioselective chloroboration of carbonyls was successfully achieved to give chiral secondary or tertiary α-chloroboronates, the important intermediates to access enantioenrich multisubstituted stereocenters. These versatile products can be surprisingly attained through this simple and mild process with remarkable substrate scope expansion and functional group tolerance. Additionally, these reactions can proceed well on large scales, giving more practical values in the application.
A regioselective carbosilylation of alkenes has emerged as a powerful strategy to access molecules with functionalized silylated alkanes, by incorporating silyl and carbon groups across an alkene double bond. However, to the best of our knowledge, organic fluorides have never been used in this protocol. Here we disclose the catalyst-free carbosilylation of alkenes using silyl boronates and organic fluorides mediated by tBuOK. The main feature of this transformation is the selective activation of the C-F bond of an organic fluoride by the silyl boronate without undergoing potential side-reactions involving C-O, C-Cl, heteroaryl-CH, and even CF3 groups. Various silylated alkanes with tertiary or quaternary carbon centers that have aromatic, hetero-aromatic, and/or aliphatic groups at the β-position are synthesized in a single step from substituted or non-substituted aryl alkenes. An intramolecular variant of this carbosilylation is also achieved via the reaction of a fluoroarene with a ω-alkenyl side chain and a silyl boronate.
Phosphorus‐ or sulfur‐centered radicals generated from the reaction of manganese(III) acetate with dialkyl phosphonates or arylthiols undergo selective additions to conjugated alkynes followed by cyclization and rearomatization to afford 2‐phosphonyl‐ or 2‐thioaryl‐substituted indenones in fair to good yields.
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