K2CO3-Catalyzed Synthesis of Chromones and 4-Quinolones through the Cleavage of Aromatic C–O Bonds
摘要:
Phenol-derived electrophiles are favorable substrates because phenols are naturally abundant or can be readily prepared from other aromatic compounds. However, the cleavage of aromatic C-O bonds Is a great challenge because of their high energy. K2CO3-catalyzed intramolecular cyclization of 1-(2-alkoxyphenyl)-3-akylpropane-1,3-dlone and 3-(alkylimino)-1-(2-methoxyphenyl)-2-methylpropan-1-one derivatives via the selective cleavage of aromatic C-O bonds Is reported. The corresponding chromone and 4-quinolone derivatives were obtained in reasonable yields.
Synthesis of Dibenzoylmethane Derivaives and Inhibition of Mutagenicity in Salmonella typhimurium.
作者:Tominari CHOSHI、Shigenori HORIMOTO、Ching Y. WANG、Hisamitsu NAGASE、Masataka ICHIKAWA、Eiichi SUGINO、Satoshi HIBINO
DOI:10.1248/cpb.40.1047
日期:——
Twenty dibenzoylmethanes with methyl, methoxy, bromo, chloro, or fluoro substitution on either one or both benzene rings were synthesized and assayed for inhibition of the mutagenicity of 2-nitrofluorene in S. typhimurium TA98. 2, 2-Dimethoxy, 3, 3-dimethoxy and 3, 3, 4, 4-tetramethoxydibenzoylmethane was as active as dibenzoylmethane. None of the halogen-substituted dibenzoylmethanes were active. These results demonstrate that dibenzoylmethanes can inhibit the mutagenicity of 2-nitrofluorene, and that modifications made on the benzene rings of dibenzoylmethane cannot enhance the antimutagencity of this parent compound.
Significantenhancement of both the rate and the chemoselectivity of iron‐catalyzed oxidative coupling of phenols can be achieved in fluorinated solvents, such as 1,1,1,3,3,3‐hexafluoropropan‐2‐ol (HFIP), 2,2,2‐trifluoroethanol (TFE), and 1‐phenyl‐2,2,2‐trifluoroethanol. The generality of this effect was examined for the cross‐coupling of phenols with arenes and polycyclic aromatic hydrocarbons (PAHs)
Metal‐Free, DBU‐Mediated, Microwave‐Assisted Synthesis of Benzo[
<i>c</i>
]xanthones by Tandem Reactions of Alkynyl‐1,3‐diketones
作者:Yi‐En Liang、Balaji D. Barve、Yao‐Haur Kuo、Hsu‐Wei Fang、Ting‐Shen Kuo、Wen‐Tai Li
DOI:10.1002/adsc.202001169
日期:2021.1.19
base‐mediated, green, microwave‐assisted efficient preparation of a diverse benzoxanthone library from variety of readily accessible γ‐alkynyl 1,3‐diketones is reported. The synthesis is based on tandem reactions involving intramolecular cyclization, propargyl‐allenyl isomerization, and electrocyclization in onepot. Some of the benzoxanthones are also synthesized by the one‐pot reaction of 1,3‐diketone and