Pyran Annulation: Asymmetric
Synthesis of
2,6-Disubstituted-4-methylene
Tetrahydropyrans
Gary E. Keck,*Jonathan A. Covel,Tobias Schiff, andTao Yu
Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
keck@chemistry.utah.edu
Received January 30, 2002
Abstract:
A reaction process for the asymmetric construction of a variety of cis or trans disubstituted pyrans is described. This sequences allows for
the asymmetric convergent union of two aldehydes with silyl-stannane reagent 1 in a two-step process: catalytic asymmetric allylation of the
first aldehyde using 1 with a BITIP catalyst, followed by reaction of the alcohol so obtained with a second aldehyde and TMSOTf.
