Total synthesis of ochnaflavone

• Monica M. Ndoile and
• Fanie R. van Heerden

Beilstein J. Org. Chem. 2013, 9, 1346–1351, doi:10.3762/bjoc.9.152

• ]. The flavonoid units in these compounds are joined in a symmetric or asymmetric manner and can either be identical or nonidentical. In addition, the two flavonoid units can be linked through a C–C bond or C–O–C bond. Many biflavonoids consist of an interflavonoid linkage between ring B of one moiety

Tricyclic flavonoids with 1,3-dithiolium substructure

• Lucian G. Bahrin,
• Peter G. Jones and
• Henning Hopf

Beilstein J. Org. Chem. 2012, 8, 1999–2003, doi:10.3762/bjoc.8.226

• synthesized from a tricyclic flavonoid bearing a 1,3-dithiolium-2-yl unit as C ring [15]. These complexes have been electrochemically investigated to provide a better understanding of enzymatic activities in thermophilic and hyperthermophilic organisms. This paper outlines the synthesis of novel tricyclic

• proved by X-ray analysis. The structure of tricyclic flavonoid cation 7a is presented in Figure 5. Structures of the perchlorate salts proved to be disordered, so the tetraphenylborate anion was used instead. The bond length C20–N21, 1.311(2) Å, corresponds to a double bond and thus to a formal positive

• . Polycyclic flavonoids. Diastereoisomers of flavonoids 6. Molecular structure of flavonoid 6a in the solid state. Ellipsoids represent 50% probability levels. Torsion angle C(11)–C(2)–C(3)–S(1): −59.19(14)°. Molecular structure of flavonoid 6b in the solid state. Ellipsoids represent 50% probability levels

An efficient partial synthesis of 4′-O-methylquercetin via regioselective protection and alkylation of quercetin

• Nian-Guang Li,
• Zhi-Hao Shi,
• Yu-Ping Tang,
• Jian-Ping Yang and
• Jin-Ao Duan

Beilstein J. Org. Chem. 2009, 5, No. 60, doi:10.3762/bjoc.5.60

• ; Introduction Flavonoids, such as flavones and flavonols, are secondary plant metabolites found in many foods, especially in fruits and vegetables [1][2]. Quercetin (1) (Figure 1), the major individual non-polymeric molecule among the polyphenols represents 60–75% of the flavonoid intake [3]. Quercetin is a

• hydroxy groups at positions 3 and 7 with chloromethyl ether as well as the ability to remove the protecting groups under different reaction conditions. This reported protocol could be applied to the selective synthesis of other O-methylflavonoid isomers as well as to other flavonoid metabolites with other

• functions such as sulfate or glucuronide groups. These compounds will allow structure–activity relationship studies of flavonoids to be carried out. Their easily obtained labeled forms will give access to isotopic dilution dosage by LC-MS or LC-MS/MS and will help in the identification of unknown flavonoid

Multiple hydride reduction pathways in isoflavonoids

• Auli K. Salakka,
• Tuija H. Jokela and
• Kristiina Wähälä

Beilstein J. Org. Chem. 2006, 2, No. 16, doi:10.1186/1860-5397-2-16

• reductions, must reflect the good stabilization obtainable via resonance heteroring stabilization (10) in the isoflavones. As already mentioned, this is in contrast to the behaviour of simple non-flavonoid β-alkoxy-α,β-unsaturated ketones which prefer 1,2-attack by hydride. Isoflavenes (7, 8) and isoflavans