Oxovanadium(V)-Induced Cross-Coupling Reaction between Two Ligands of Organozinc Compounds
作者:Toshikazu Hirao、Takashi Takada、Akiya Ogawa
DOI:10.1021/jo9919106
日期:2000.3.1
Oxovanadium(V) compounds such as VO(OEt)Cl(2) serve as useful oxidants for organozinc compounds, providing the corresponding cross-coupling products derived from two ligands of organozinc compounds. In particular, triorganozincates undergo selective cross-coupling smoothly by the action of oxovanadium(V).
A palladium-catalyzed, iodine-mediatedelectrophilicannulation between 2-(1-alkynyl)biphenyl and disulfide has been developed. With the combination of PdCl2 and I2, a variety of 2-(1-alkynyl)biphenyls underwent electrophilicannulations with various disulfides successfully to afford the corresponding 9-sulfenyl phenanthrenes in moderate to excellent yields.
We describe a novel and highly efficient metal-free strategy to construct 9,9-disubstituted fluorenes and phenanthrenes via the TfOH-catalyzed cycloisomerizations of o-alkynylbiaryls. Notably, the significant effects of the electronic properties and steric hindrance of the alkyne terminus on the reaction selectivity have been observed.
A formalinsertion reaction of two molar amounts of arynes into a C−H bond of terminal alkynes is efficaciously catalyzed by copper(I) chloride, giving 2-alkynylbiaryls in one step.
BF<sub>3</sub> ⋅ Et<sub>2</sub>O‐Mediated Annulation of 2‐Alkynyl Biaryls with <i>N</i>‐(Arylthio) Succinimides: An Efficient Approach to Access 9‐Sulfenylphenanthrenes
A simple and effective method for the synthesis of 9-sulfenylphenanthrenes was developed. The reaction proceeds through BF3 ⋅ OEt2-mediated annulation of 2-alkynyl biaryls with N-arylthio succinimides at roomtemperature. With this method, a series of 9-sulfenylphenanthrenes was efficiently obtained in good to excellent yields under mild and metal-free conditions.