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Remote Enantioselective Friedel–Crafts Alkylations of Furans through HOMO Activation
Author(s) -
Li JunLong,
Yue CaiZhen,
Chen PengQiao,
Xiao YouCai,
Chen YingChun
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201403082
Subject(s) - friedel–crafts reaction , electrophile , enantioselective synthesis , reactivity (psychology) , regioselectivity , alkylation , chemistry , homo/lumo , catalysis , amine gas treating , organic chemistry , medicinal chemistry , combinatorial chemistry , molecule , medicine , alternative medicine , pathology
Catalytic asymmetric Friedel–Crafts alkylation is a powerful protocol for constructing a chiral C(sp 2 )C(sp 3 ) bond. Most previous examples rely on LUMO activation of the electrophiles using chiral catalysts with subsequent attack by electron‐rich arenes. Presented herein is an alternative strategy in which the HOMO of the aromatic π system of 2‐furfuryl ketones is raised through the formation of a formal trienamine species using a chiral primary amine. Exclusive regioselective alkylation at the 5‐position occurred with alkylidenemalononitriles, and high reactivity and excellent enantioselectivity (up to 95 % ee ) was obtained by this remote activation.