Multicatalytic, asymmetric Michael/Stetter reaction of salicylaldehydes and activated alkynes
作者:Claire M. Filloux、Stephen P. Lathrop、Tomislav Rovis
DOI:10.1073/pnas.1002830107
日期:2010.11.30
We report the development of a multicatalytic, one-pot, asymmetric Michael/Stetter reaction between salicylaldehydes and electron-deficient alkynes. The cascade proceeds via amine-mediated Michael addition followed by an
N
-heterocyclic carbene-promoted intramolecular Stetter reaction. A variety of salicylaldehydes, doubly activated alkynes, and terminal, electrophilic allenes participate in a one-step or two-step protocol to give a variety of benzofuranone products in moderate to good yields and good to excellent enantioselectivities. The origin of enantioselectivity in the reaction is also explored;
E
/
Z
geometry of the reaction intermediate as well as the presence of catalytic amounts of catechol additive are found to influence reaction enantioselectivity.