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Decarboxylative [4+2] Cycloaddition by Synergistic Palladium and Organocatalysis
Author(s) -
Leth Lars A.,
Glaus Florian,
Meazza Marta,
Fu Liang,
Thøgersen Mathias K.,
Bitsch Emma A.,
Jørgensen Karl Anker
Publication year - 2016
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201607788
Subject(s) - cycloaddition , chemistry , palladium , decarboxylation , iminium , catalysis , organocatalysis , synergistic catalysis , yield (engineering) , organic chemistry , boronic acid , combinatorial chemistry , enantioselective synthesis , materials science , metallurgy
A novel reaction based on synergistic catalysis, combining palladium‐ and organocatalysis has been developed. The palladium catalyst activates vinyl benzoxazinanones via a decarboxylation to undergo a [4+2] cycloaddition with iminium‐ion activated α,β‐unsaturated aldehydes. The reaction is demonstrated to proceed for a number of combinations of vinyl benzoxazinanones reacting with α,β‐unsaturated aldehydes, providing highly substituted vinyl tetrahydroquinolines in good to high yields, and excellent enantio‐ and diastereoselectivities (>98 % ee and >20:1 d.r.). The palladium catalyst used in the synergistic catalysis can be re‐used in a one‐pot sequential coupling reaction with an aromatic boronic acid forming the coupling product in 95 % yield, >20:1 d.r. and 99 % ee .