reaction tolerates a variety of functionalized internal and terminal alkynes to afford trans‐β‐alkoxyvinylbenziodoxoles, which represent versatile precursors to stereochemically well‐defined multisubstituted vinyl ethers. The reaction is proposed to involve cleavage of the I−F bond of FBX by BF3, followed by electrophilic activation of the alkyne by the resulting cationic IIII species that triggers the
Oxidative heterocoupling between two Grignardreagents RMgX and R′MgX is made possible by manganese catalysis with O2 as an oxidant. This procedure, development of which was based on mechanistic analysis of the corresponding homocoupling reaction, can be steered towards the heterocoupling product at the expense of the homocoupling products by judicious choice of the R and R′ groups (see examples).
Ligand Effects on the Pd-Catalyzed Cross-Coupling Reaction of 3-Iodoalk-2-enoates with Propargyl/1,2-Allenylic Metallic Species: An Efficient Regiodivergent Synthesis of 2,4,5-Trienoates
作者:Jinbo Zhao、Yihua Yu、Shengming Ma
DOI:10.1002/chem.200901287
日期:2010.1.4
makes a big difference: The 1,3‐lithiumshift of propargyl/1,2‐allenyl lithium has been tuned and applied in a subsequenttransmetalation and Pd‐catalyzed Negishi couplingreaction with 3‐iodoalk‐2‐enoates to give a highly regioselective and regiodivergent synthesis of 2,4,5‐trienoates. It was discovered that ligands play a very important role in the cross‐couplingreactions with respect to both regioselectivity
In Situ Generation of Alkynylzinc and Its Subsequent Negishi Reaction in a Flow Reactor
作者:Mohanraj Kandasamy、Yu- Hsuan Huang、Balaji Ganesan、Gopal Chandru Senadi、Wei-Yu Lin
DOI:10.1002/ejoc.201900471
日期:2019.7.23
and highly efficient method for the synthesis of internal alkynes or 1,3‐enynes was achieved in a continuous flow system through the generation of an alkynylzinc reagent from lithium acetylide and zinc bromide followed by a Pd‐catalyzed cross‐coupling with aryl or vinyl iodides.
Phenyl- and vinyllithiums having an alkyl substituent at their ortho- and cis-position, respectively, readily added to alkynes in the presence of 5 mol% of Fe(acac)(3). The reaction of o-(trimethylsilyl)phenyllithium with alkynes gave benzosiloles through an addition-cyclization sequence.