アンチWacker 型環化反応による２，３－二置換インデノールの合成法

抄録

Indenols can be synthesized by aryl, alkenyl, and alkylative cyclization of 2-ethynylbenzaldehydes with organoboronic reagents via palladium(0)-catalyzed 'anti-Wacker'- type oxidation addition. This method is suitable for their combitatorial synthesis due to not only facile preparation of 2-ethynylbenzaldehydes from 2-halobenzaldehydes and terminal alkynes by the Sonogashira reaction but also availability of the boronic reagents. The trans-addition of intramolecur electrophilic carbonyls and boronic reagents to the alkyne is enhanced by aryl and alkenyl substitutions at the terminal alkyne carbon. In comparison with other transition-metal catalyzed preparation of indenols from 2-halobenzaldehydes or 2-formylphenylboronic acids with internal alkynes, our procedure enables to introduce sterically and electronically similar two substituents at 2- and 3- positions in regioselective manner.

fig.1