113931-97-8Relevant articles and documents
Chromium-Salen Complex/Nitroxyl Radical Cooperative Catalysis: A Combination for Aerobic Intramolecular Dearomative Coupling of Phenols
Nagasawa, Shota,Fujiki, Shogo,Sasano, Yusuke,Iwabuchi, Yoshiharu
, p. 6952 - 6968 (2021/05/29)
We describe an aerobic intramolecular dearomative coupling reaction of tethered phenols using a catalytic system consisting of a chromium-salen (Cr-salen) complex combined with a nitroxyl radical. This novel catalytic system enables formation of various spirocyclic dienone products including those unable to be accessed by previously reported methods efficiently under mild reaction conditions.
Free-radical-scavenging and xanthine oxidase inhibitory constituents from Stereospermum personatum
Sampath Kumar,Tiwari, Ashok K.,Venkat Reddy,Aparna,Jagadeeshwar Rao,Zehra Ali,Madhusudana Rao
, p. 1615 - 1621 (2008/09/17)
Bioassay-guided fractionation of different extracts of both stem and stem bark of Stereospermum personatum led to the isolation of free-radical-scavenging and xanthine oxidase inhibitory molecules along with three new anthraquinones, sterequinones F-H (1-3), a new naphthoquinone, sterequinone I (4), two new phenethyl esters, 2(4′-hydroxyphenyl)ethyl undecanoate (14) and 2(4′-hydroxyphenyl)ethyl nonacosanoate (15), and a new 3,4,5-trimethoxycinnamyl ether, 2-methoxy-4-[3′-(3″,4″, 5″trimethoxyphenyl)allyloxymethyl]phenol (16), together with known compounds. The antioxidant and xanthine oxidase inhibitory potentials of the isolated compounds are reported.
Allylidenetriphenylphosphorane as a Bifunctional Reagent: Synthesis of Cyclopentenones and α,β-Unsaturated Ketones with (3-(Alkoxycarbonyl)-2-ethoxy-2-propylidene)triphenylphosphorane
Hatanaka, Minoru,Himeda, Yuichiro,Imashiro, Ritsuo,Tanaka, Yasuhiro,Ueda, Ikuo
, p. 111 - 119 (2007/10/02)
When (3-(ethoxycarbonyl)-2-ethoxy-2-propenylidene)triphenylphosphorane (6) was allowed to react with α-bromo ketones 8a-d in dichloromethane in the presence of Cs2CO3 at room temperature, a annulation occured and led to the formation of the corresponding 2-ethoxycyclopentadienes 9a-d in excellent yields.Similarly, bromo thioester 8g underwent the annulation to give 4-(ethylthio)cyclopentadiene 9g.Secondary bromides 2-bromo-3-pentanone and 2-bromocyclohexanone also afforded tetrasubstituted cyclopentadienes 9e and 9f in moderate yields when 2 equiv of 6 was used.The annulation is belived to proceed through a sequence involving a stepwise alkylation at the γ position of 6 and an intramolecular Wittig reaction because of the fact that intermediate 11 was isolated.The resulting 2-ethoxycyclopentadienes 9a-g were converted quantitatively into the corresponding cyclopentenones 10a-g upon mild acid treatment.Furthermore, allylidenetriphenylphosphorane underwent a carbon elongation at both ends of the three-carbon unit via an alkylation-Wittig reaction sequence. (3-(tert-Butoxycarbonyl)-2-ethoxy-2-propenylidene)triphenylphosphorane (7) reacted first with alkyl halides and then with aldehydes in the presence of Cs2CO3 to give enol ethers 23a-f, which were converted into α,β-unsaturated ketones 20, 21, and 25c-f by hydrolysis of the enol ether and then decarboxylation.In this way, shogaol (29), the pungent principle component of ginger, was conveniently synthesized starting from 2-methoxy-4-methylphenol.
