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Enantioselective Michael Addition of 4‐Hydroxycoumarins to β,γ‐Unsaturated α‐Oxophosphonates Catalysed by a Bifunctional Squaramide Bearing a Structurally Rigid 9,10‐Ethylene‐9,10‐dihydroanthracene Skeleton
Author(s) -
Chang Xufang,
Wang Qiaohui,
Wang Youming,
Song Haibin,
Zhou Zhenghong,
Tang Chuchi
Publication year - 2013
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201201573
Subject(s) - squaramide , bifunctional , chemistry , enantioselective synthesis , michael reaction , nucleophile , amine gas treating , organocatalysis , quenching (fluorescence) , organic chemistry , medicinal chemistry , catalysis , physics , quantum mechanics , fluorescence
A bifunctional squaramide based on ( R , R )‐11,12‐diamino‐9,10‐ethylene‐9,10‐dihydroanthracene has been developed, and it has demonstrated great advantages over previously reported organocatalysts in the asymmetric Michael addition of 4‐hydroxycoumarins to β,γ‐unsaturated α‐oxophosphonates. Upon quenching the generated β‐4‐hydroxy‐2‐oxo‐2 H ‐chromen‐3‐yl‐substituted acylphosphonate intermediates with DBU and an alcohol or amine as a second nucleophile, the corresponding β‐substituted carboxylates or amides were obtained in acceptable to excellent yields and with high levels of enantioselectivity (80–97 % ee ) in a one‐pot fashion.