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Organocatalytic Asymmetric Friedel–Crafts Reaction of Sesamol with Isatins: Access to Biologically Relevant 3‐Aryl‐3‐hydroxy‐2‐oxindoles
Author(s) -
Kumar Akshay,
Kaur Jasneet,
Chauhan Pankaj,
Singh Chimni Swapandeep
Publication year - 2014
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201301546
Subject(s) - chemistry , friedel–crafts reaction , sesamol , cinchona , organic chemistry , thiourea , isatin , bifunctional , enantiomeric excess , aryl , moiety , cycloaddition , medicinal chemistry , enantioselective synthesis , catalysis , alkyl , antioxidant
The Friedel–Crafts reaction of electron‐rich phenols with isatins was developed by employing bifunctional thiourea–tertiary amine organocatalysts. Cinchona alkaloid derived thiourea epi CDT‐ 3 a efficiently catalyzed the Friedel–Crafts‐type addition of phenols to isatin derivatives to provide 3‐aryl‐3‐hydroxy‐2‐oxindoles 7 and 9 in good yield (80–95 %) with good enantiomeric excess (83–94 %). Friedel–Crafts adduct 7 t was subjected to a copper(I)‐catalyzed azide–alkyne cycloaddition to obtain biologically important 3‐aryl‐3‐hydroxy‐2‐oxindole 11 in good enantiomeric excess and having a 1,2,3‐triazole moiety.