Total synthesis of two isoflavone C-glycosides: genistein and orobol 8-C-beta-D-glucopyranosides.
Genistein and orobol 8-C-beta-D-glucopyranosides (1 and 3) were firstly synthesized in overall yields of 39% and 41% from 2,4-di-O-benzylphloroacetophenone (4), as follows: (1) the formation of the chalcone (6, 7) by aldol condensation of the benzyl-protected C-glycosylphloroacetophenone (5), a key intermediate of the total synthesis of 1 and 3 and synthesized by a C-glycosylation method involving the O-->C glycoside rearrangement of 4 in 96% yield; (2) the formation of isoflavones (10, 11 and 12, 13) by the formation of acetals by oxidative rearrangement of the protected chalcones (8 and 9) using Tl(NO3)3, followed by acid-catalyzed cyclization; (3) a final debenzylation by hydrogenolysis.
Sato
Shingo
S
Department of Chemistry and Chemical Engineering, Faculty of Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa-shi, Yamagata 992-8510, Japan. shingo-s@yz.yamagata-u.ac.jp
Hiroe
Kaoru
K
Kumazawa
Toshihiro
T
Jun-ichi
Onodera
O
D005419:Flavonoids / Q000138:chemical synthesis*; D019833:Genistein / Q000138:chemical synthesis*; D005947:Glucose / Q000031:analogs & derivatives*
D005419:Flavonoids; D019833:Genistein; D005947:Glucose; C059811:orobol