145822-68-0Relevant articles and documents
On the reaction of prop-2-enylidenetriphenylphosphorane derivatives. Novel synthesis of the azulene ring system
Takayasu, Tohru,Nitta, Makoto
, p. 681 - 686 (2007/10/03)
Reaction of prop-2-enylidenetriphenylphosphorane derivatives with several tropones has been studied in an attempt to provide a short new route to the azulene ring system. (2-Ethoxyprop-2-enylidene)triphenylphosphorane 4 reacts with 2-chloro-, 2-methoxy- and 2,3,5,7-tetrachlorotropones 7a-c to give azulene derivatives 8 and 9 in moderate yields. On the other hand, reaction of [2-ethoxy-3-(ethoxycarbonyl)prop-2-enylidene]triphenylphosphorane 6 with tropones 7a,c results in the formation of azulene esters 10 and 11 in low yields, whilst that with tropone 7b gives no azulene and substrate 7b is recovered. In order to gain insight into the mechanistic pathways, reaction of phosphoranes 4 and 6 with deuteriated tropones 14a,b which are the corresponding trideuteriated derivatives of compounds 7a,b, have also been studied. Furthermore, compound 4 reacts also with 5-(dimethylaminomethylene)cyclopenta-1,3-dienecarbaldehyde 33 to give 6-ethoxyazulene 37 in moderate yield.
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.
