New catalysts for the base-promoted isomerization of epoxides to allylic alcohols. Broadened scope and near-perfect asymmetric induction.
Optically active (1S,3R,4R)-3-[N-(trans-2,5-dialkyl)pyrrolidinyl]methyl-2-azabicyclo-[2.2.1]heptanes were evaluated as catalysts for the enantioselective beta-elimination of meso-epoxides. The (2R,5R)-dimethylpyrrolidinyl-substituted catalyst 4 exhibited exceptionally high enantioselectivity and reactivity, and several substrates were rearranged with enantioselectivities of 98-99% ee. In addition, the use of 4 allowed the first successful, true catalytic rearrangement of the difficult substrates cyclopentene oxide (81%, 96% ee) and (Z)-4-octene oxide (80%, 91% ee).
Bertilsson
Sophie K
SK
Department of Organic Chemistry, Institute of Chemistry, Uppsala University, Box 531, S-751 21 Uppsala, Sweden.
Södergren
Mikael J
MJ
Andersson
Pher G
PG