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(Journal Article) |
Proceedings of the National Academy of Sciences of the United States of America 107 (48): 20666-71 (2010)
Multicatalytic, asymmetric Michael/Stetter reaction of salicylaldehydes and activated alkynes.
Claire M Filloux
,
Stephen P Lathrop
,
Tomislav Rovis
ABSTRACT
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.