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Phosphine‐Catalyzed Chemoselective [4+3] Cycloaddition of Alminine Esters and β′‐acetoxy Allenoates for Divergent Synthesis of Azepines
Author(s) -
Dai Zonghao,
Zhu Jin,
Wang Jiahua,
Su Wenbo,
Yang Fulai,
Zhou Qingfa
Publication year - 2020
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201901132
Subject(s) - azepine , chemistry , phosphine , intramolecular force , cycloaddition , catalysis , substrate (aquarium) , maleimide , combinatorial chemistry , aldimine , stereochemistry , medicinal chemistry , organic chemistry , oceanography , geology
Abstract Abstract Text. A general method for the synthesis of structural diversity and complexity of azepines from aldimine esters and β′‐acetoxy allenoates is reported. Under phosphine catalysis, a [4+3] cycloaddition for the formation of 1,3‐dihydro‐2 H ‐azepine‐2,2,4‐tricarboxylates was achieved with broad substrate scope under mild reactions. A switchable process was given and a variety of important 2,3‐dihydrochromeno[4,3‐b]azepin‐6(1 H )‐ones were selectively formed when the reaction was performed in the presence of Cs 2 CO 3 and PPh 3 , which involved an intramolecular ester group migration and subsequent lactonization of 1,3‐dihydro‐2 H ‐azepine‐2,2,4‐tricarboxylates. Besides easy handle process, high synthetic value of resulting products, it is worth to note that this work showed the novel example of 1,5‐ethoxycarbonyl migration.