A novel and practical method for the selenosulfonation of alkynes with the insertion of sulfur dioxide has been developed. A series of β-(seleno)vinyl sulfones with high levels of regio-and stereoselectivity have been prepared. The key features of this reaction include a broad substrate scope, excellent functional-group tolerance, and amenability to scale-up synthesis. A plausible radical mechanism is proposed to illustrate this reaction.
The construction of multi-stereocenters by a transition metal-catalyzed cross-coupling reaction is a major challenge. The catalytic desymmetric functionalization of unactivated alkenes remains largely unexplored. Herein, we disclose -a desymmetric dicarbofunctionalization of 1,6-dienes via a nickel-catalyzed reductive cross-coupling reaction. The leverage of the underdeveloped chiral 8-Quinox enables the Ni-catalyzed desymmetric carbamoylalkylation of both unactivated mono-and disubstituted alkenes to form pyrrolidinone bearing two nonadjacent stereogenic centers in high enantio-and stereoselectivitives with broad functional-group tolerance. The synthetic application of pyrrolidinones allows the rapid access to complex chiral fused-heterocycles.
Herein, we leverage the Ni-catalyzed enantioselective reductive dicarbofunctionalization of internal alkenes with alkyl iodides to enable the synthesis of chiral pyrrolidinones bearing vicinal stereogenic centers. The application of newly developed 1-Nap Quinim is critical for formation of two contiguous stereocenters in high yield, enantioselectivity, and diastereoselectivity. This catalytic system also improves both the yield and enantioselectivity in the synthesis of α,α-dialkylated γlactams. Computational studies reveal that the enantiodetermining step proceeds with a carbamoyl-Ni I intermediate that is reduced by the Mn reductant prior to intramolecular migratory insertion. The presence of the t-butyl group of the Quinim ligand leads to an unfavorable distortion of the substrate in the TS that leads to the minor enantiomer. Calculations also support an improvement in enantioselectivity with 1-Nap Quinim compared to p-tol Quinim.
An economical, practical, and environmentally benign azol-halogenation protocol of alkenes was developed, which provides a general approach to construct a series of structurally diverse β-halogenated amine derivatives.
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