Synthesis and Biological Evaluation of Substituted Flavones as Gastroprotective Agents
摘要:
Flavone (1) was found to protect against ethanol-induced gastric damage in rats; however, it is known that certain compounds in the flavone class, including flavone itself, are inducers of hepatic drug metabolizing enzymes. With the hope of identifying gastroprotective flavones that have minimal effects on drug metabolizing enzymes, we have synthesized and evaluated selected flavone analogs. Gastroprotective potency in the ethanol model was retained by methoxy substitution in the 5-position (4) and by methoxy (12) or methyl (14) substitution in the 7-position. A number of substituted analogs of the potent molecule 5-methoxyflavone (4) were also synthesized, and in many cases, these substitutions provided gastroprotective molecules. In order to assess liver enzyme induction potential, two of the gastroprotective flavones, 7-methoxyflavone (12) and 5-methoxy-4'-fluoroflavone (26), were examined for their effect on liver microsomal cytochrome P450 and 7-ethoxyresorufin O-dealkylase (CYP1A) activity. These two compounds caused minimal changes in the cytochrome P450 concentration and were considerably less potent than beta-naphthoflavone as inducers of CYP1A enzyme activity. Furthermore, following oral administration to rats, 5-methoxy-4'-fluoroflavone (26) was found to protect against indomethacin-induced gastric damage. These results indicate that, through appropriate substitution, flavones can be obtained that are gastroprotective but have minimal effects on drug-metabolizing enzymes.
The Ru(II)-catalyzed C-H activation and annulation reaction of salicylaldehydes and disubstitutedalkynes affords chromones in high yields. This reaction works with terminal alkynes also and tolerates wide range of sensitive...
Regioselective synthesis of flavone derivatives via DMAP-catalyzed cyclization of o-alkynoylphenols
作者:Masahito Yoshida、Yuta Fujino、Koya Saito、Takayuki Doi
DOI:10.1016/j.tet.2011.09.063
日期:2011.12
A catalytic amount of DMAP promoted cyclization of o-alkynoylphenols via a 6-endo cyclization mode leading to flavone derivatives in high yields without forming 5-exo cyclizedauronederivatives. Utilizing this method, methoxy substituted flavone and alkyl substituted γ-benzopyranone derivatives were synthesized.
Rh(III)-catalyzed C–H activation of salicylaldehyde followed by an insertion reaction with sulfoxonium ylides and cyclization is applied to the synthesis of flavonoids. This one-pot strategy exhibits good functional group tolerance and gives flavones in moderate-to-good yields.
The palladium-catalyzedintramolecular acylation of alkenyl bromides and aldehydes was developed for an efficient synthesis of 4H-chromen-4-ones. With Pd(PPh3)4/Xphos as the catalyst and K2CO3 as the base, this protocol was applied to synthesize a small library of diversely functionalized flavonoids in moderate to good yields in 1,4-dioxane.
开发了钯催化的烯基溴和醛的分子内酰化反应,以有效合成4 H -chromen-4-ones。以Pd(PPh 3)4 / Xphos为催化剂,以K 2 CO 3为碱,该方案被用于合成少量的,功能多样的黄酮类化合物,在1,4-二恶烷中的产率为中等。
Reagent-free intramolecular hydrofunctionalization: a regioselective 6-<i>endo-dig</i> cyclization of <i>o</i>-alkynoylphenols
Solvent-directed intramolecular hydrofunctionalization of readily available o-alkynoylphenols 1 was successfully achieved under reagent-free conditions. The hydrofunctionalization of 1 occurred by nucleophilic attack on the phenolic oxygen followed by consecutive migration of the phenolic H atom to the alkyne center, eventually affording γ-benzopyranones 2. The phenol O–H group forms intramolecular H-bonds
在无试剂条件下成功实现了容易获得的邻炔基酚1的溶剂导向分子内氢官能化。1的氢官能化通过对酚氧的亲核攻击随后酚氢原子连续迁移到炔烃中心而发生,最终得到 γ-苯并吡喃酮2。酚 O-H 基团与羰基形成分子内 H 键,我们预测这些 H 键在极性溶剂存在下可以扭曲成它们最优选的构象。区域选择性 6 -endo-dig环化似乎在热力学上优于 5 -exo-dig循环化,由 DFT 计算支持。该策略之所以引人注目,是因为它无试剂、区域选择性、原子经济性高、原子、碳和反应质量效率高。