Cu(OTf)(2) and 1 equiv of a Brønstedacid, such as CF(2)HCO(2)H, in (CH(2)Cl)(2) at 100 degrees C, the decarbonylated naphthalene products 5 were obtained in high yields. Similarly, the Cu(OTf)(2)-H(2)O-promoted reaction of the enynals 7 with an alkyne 2 afforded the corresponding [4+2] benzannulation products, decarbonylated benzene derivatives 8, in good yields. Both AuX(3)- and Cu(OTf)(2)-catalyzed
ZnCl2-catalyzed [4 + 2] benzannulation of 2-ethynylbenzaldehydes with alkynes: Selective synthesis of naphthalene derivatives
作者:Xiao-Li Fang、Ri-Yuan Tang、Xing-Guo Zhang、Ping Zhong、Chen-Liang Deng、Jin-Heng Li
DOI:10.1016/j.jorganchem.2010.09.062
日期:2011.1
Zn-catalyzed [4 + 2] benzannulation of 2-ethynylbenzaldehydes with alkynes is described for the selectivesynthesis of naphthalene derivatives. In the presence of ZnCl2, a variety of 2-ethynylbenzaldehydes underwent the [4 + 2] benzannulation reactions with alkynes to selectively afford the corresponding naphthalene derivatives in moderate to good yields.
Photochemical Rearrangement of Enediynes: Is a “Photo-Bergman” Cyclization a Possibility?
作者:Ariella Evenzahav、Nicholas J. Turro
DOI:10.1021/ja9722943
日期:1998.3.1
when the double bond of the enediyne was of aromatic character. Triplet sensitization studies and laser flash photolysis experiments point toward radical mechanisms taking place during formation of both classes of products, with the photoreduction products forming from the excited triplet state and the cyclized naphthyl products forming from either the singlet or the triplet states. For the cyclization
Electron-Transfer-Induced Reductive Cleavage of Phthalans: Reactivity and Synthetic Applications
作者:Ugo Azzena、Salvatore Demartis、Giovanni Melloni
DOI:10.1021/jo9604548
日期:1996.1.1
The behavior of phthalan (1a) was investigated under conditions of electron transfer from alkali metals in aprotic solvents. Reaction with lithium in the presence of a catalytic amount of naphthalene in THF led to the reductive cleavage of an arylmethyl carbon-oxygen bond, with formation of a stable dilithium compound. Trapping of this intermediate with several electrophiles (alkyl halides, carbonyl derivatives, CO2) was successful. The extension of this procedure to several substituted phthalans (1b-i) was investigated, and the regiochemistry as well as the synthetic usefulness of these reactions are discussed.
Iron-catalyzed Benzannulation Reactions of 2-Alkylbenzaldehydes and Alkynes Leading to Naphthalene Derivatives
An efficient and practical method for the synthesis of naphthalene derivatives via Fe(III)-catalyzed benzannulation of 2-(2-ozoethyl)-benzaldehydes and alkynes has been developed. The system holds the advantages of cheap catalysts, wide substrate scope, and mild reaction conditions.