jo035753t_si_001.pdf (31.44 kB)
Concise Synthesis of Anti-HIV-1 Active (+)-Inophyllum B and (+)-Calanolide A by Application of (−)-Quinine-Catalyzed Intramolecular Oxo-Michael Addition
journal contribution
posted on 2004-04-16, 00:00 authored by Etsuko Sekino, Takuya Kumamoto, Tomohiro Tanaka, Tomoko Ikeda, Tsutomu Ishikawa(−)-Quinine-catalyzed intramolecular oxo-Michael addition (IMA) of 7-hydroxy-5-methoxy-8-tigloylcoumarins was developed for the enantioselective construction of 2,3-dimethyl-4-chromanone
systems in the context of the asymmetric synthesis of anti-HIV-1 active Calophyllum coumarins.
Combination of the IMA and MgI2-assisted demethylation of the 5-methoxy group along with
isomerization of the formed chromanone systems as key steps successfully led to the concise
synthesis of (+)-inophyllum B and (+)-calanolide A, possible candidates for AIDS drugs. Further
examination of the asymmetric IMA with cinchona alkaloids lacking a methoxy group on the
quinoline skeleton suggested the influence of the methoxy substituent on stereoselectivity at the
stereogenic centers of the chromanone systems.