The Total Synthesis Of A Flavonoid Glycoside Apigenin-7-O-β-D-glucuronide

Apigenin-7-O-β-D-glucuronide, a new flavonoid glycoside isolated from Erigeron breriscapus(Vant.)Hand-Mazz, is proved to have good biological activities such as anti-ulcer,anti-dementia and anti-reflux oesophagitis .since its content in herbal plants is very low, it is important to obtain apigenin-7-O-β-D-glucuronide from chemistry synthesis.To our kowledge, there is no report on the total synthesis of apigenin-7-O-B-D-glucuro-nide to date. In this paper we mainly studied the total synthesis of apigenin-7-O-β-D-glu curonide. The main contents of this paper are as follows:Firstly,5,7,4'-trihydroxyflavone, which is a main intermediate for apigenin-7-O-B-D-glucuronide,was prepared through Fries rearrangement, selective methylation, Claisen-Schmidt condensation, cyclization and demethylation from the starting material——1,3,5-trihydroxybenzene.Secondly, the 2,3,4-tri-O-acetyl-l-bromo-l-deoxy-B-D-galacturonate was synthe-sized from D-glucuro nolactone by exchange-esterification, acetylation and bromiation.Thirdly,7-hydroxy-5,4'-dimacetateflavone was prepared by acetylation, benzylation and catalytic hydrogenation from 5,7,4'-trihydroxyflavone.Finally,the last fragment were connected by glycosylation and subsequently deacetylated to get the target molecule.In this paper,the main reaction mechanisms were alsp studied .The reaction process was monitored by TLC and the structures of the intermediates and target molecule were confirmed by1HNMR. In the selective methylation reaction,we used DMC in place of DMS or Mel used in the literatures.The reaction prceeded smoothy under moderate conditions. In summary The first total synthesis of apigenin 7-O-β-D-glucuronide was accomplished in eleven steps with an overall yield of 10.68%...