scholarly journals Enantioselective aza-Michael Cyclization Reaction Catalyzed by Quinine-Derived Monoquaternary Ammonium Salts: an Effective Route to Synthesize Letermovir

2021 ◽  
Vol 03 (04) ◽  
pp. e194-e199
Author(s):  
Liang Chen ◽  
Wei-Yuan Liu ◽  
Si-Ju Bi ◽  
Ting Zhou ◽  
Jing Pan ◽  
...  

A series of mono- or bis-quaternary ammonium salts derived from cinchonidine or quinine was synthesized and screened as potent phase-transfer catalysts for the reaction of aza-Michael cyclization, the key step in the synthesis of letermovir. During the reaction of aza-Michael cyclization, the screened monoquaternary ammonium salt quinine derivative Q1 transferred 7 to 8 with 91.9% yield and 58% ee. The application of Q1 was preferred, due to its enantioselectivity, the possibility of reuse, and the lower cost in large-scale preparation. Furthermore, the racemization condition of letermovir enantiomer was also explored for the possibility to develop the resolution/racemization process. With the optimal catalyst Q1 in hand, the synthesis of letermovir may be more convenient and economical in the future.

1989 ◽  
Vol 30 (13) ◽  
pp. 1683-1686 ◽  
Author(s):  
Manfred Lissel ◽  
David Feldman ◽  
Malka Nir ◽  
Mordecai Rabinovitz

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