Luan Y, Barbato KS, Moquist PN, Kodama T, Schaus SE * Boston University, USA
Enantioselective Synthesis of 1,2-Dihydronaphthalene-1-carbaldehydes by Addition of Boronates to Isochromene Acetals Catalyzed by Tartaric Acid.
J. Am. Chem. Soc. 2015;
137: 3233-3236
Key words
[4+2] cycloaddition - tartaric acid - holmium
Significance
The authors present the tartaric acid catalyzed asymmetric [4+2] cycloaddition of isochromene acetals with vinylboronates. A series of 1,2-dihydronaphthalene-1-carbaldehydes were prepared with excellent yields (up to 91%), diastereo- (dr up to >99:1), and enantioselectivities (er up to 98.5:1.5).
Comment
This method provides a facile access to chiral dihydronaphthalene building blocks that can be used to make important natural products and biological active compounds. Tartaric acid in combination with Ho(OTf)3 is highly effective for the reaction.
