The asymmetricallylicsubstitution of allylphosphates with aryl‐ and alkenylboronates catalyzed by a copper/N‐heterocyclic carbene complex was developed and the γ‐substitution products were obtained with high enantioselectivity (see scheme). To account for the observed influence of the reaction parameters a possible catalytic cycle for this process was proposed.
A new type of nucleophile, a 3‐imino nitrile carbanion generated in situ by Thorpe reaction of acetonitrile with a base, was developed successfully and applied in a Pd‐catalyzed asymmetric allylic alkylation with mono‐substituted allyl reagents under Pd/SIOCPhox catalysis, affording β‐enaminonitrile products in high yields with excellent regio‐ and enantioselectivities.
reactive nucleophile in the iridium-catalyzed allylicsubstitution of unsymmetrical substrates to give the branched oxime ethers. Among several chiral ligands evaluated, the iridium complex of pybox ligand having phenyl group catalyzed the allylicsubstitution of phosphates with high activity to form the branched oxime ethers with good enantioselectivities.
Pd-Catalyzed Allylic Isocyanation: Nucleophilic<i>N</i>-Terminus Substitution of Ambident Cyanide
作者:Taiga Yurino、Ryutaro Tani、Takeshi Ohkuma
DOI:10.1021/acscatal.9b00858
日期:2019.5.3
nitriles, which are selectively obtained in the traditional Pd(0)-catalyzed reaction, were observed. The use of phosphate as the leaving group was crucial to achieve complete regioselectivity of the ambident cyanide species as the N-terminus nucleophile. The reaction was applicable to a series of aromatic-, heteroaromatic-, vinylic-, and aliphatic-substituted allylic phosphates. The mechanistic studies
imidazole, which then reacts with a π-allyl palladium electrophile generated from an allylalcohol derivative by a palladium-based catalyst. A broad scope of substrates was suitable for this reaction. The utility of this method was demonstrated by a gram-scale reaction and subsequent elaboration of the allylation products.