Premium
Catalytic Enantioselective [5+2] Cycloaddition between Oxidopyrylium Ylides and Enals under Dienamine Activation
Author(s) -
Orue Ane,
Uria Uxue,
Reyes Efraim,
Carrillo Luisa,
Vicario Jose L.
Publication year - 2015
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201410723
Subject(s) - squaramide , enantioselective synthesis , chemistry , bifunctional , cycloaddition , organocatalysis , ylide , catalysis , octane , reactivity (psychology) , yield (engineering) , organic chemistry , stereoselectivity , bifunctional catalyst , amine gas treating , combinatorial chemistry , medicine , materials science , alternative medicine , pathology , metallurgy
Benzopyrylium ylides generated in situ from 1‐acetoxyisochroman‐4‐ones reacted with α,β‐unsaturated aldehydes in the presence of a bifunctional secondary‐amine/squaramide catalyst to furnish [5+2] cycloaddition products in good yield with high diastereo‐ and enantioselectivity. The reaction proceeds by dienamine activation and involves β,γ‐functionalization of the enal. The dienamine intermediates showed exclusive β,γ‐reactivity and provided direct access to compounds with the 8‐oxabicyclo[3.2.1]octane framework. The ability of the bifunctional secondary‐amine/squaramide catalyst to engage in hydrogen‐bonding interactions with the ylide made it particularly effective in terms of both the yield and the stereoselectivity of the transformation.