Efficient Synthesis of Tribenzohexadehydro[12]annulene and Its Derivatives in the Ionic Liquid

Abstract

A simple and efficient synthesis of tribenzohexadehydro[12]annulene and related derivatives in the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate is described. A Sonogashira coupling reaction is the key step. In this system, the amount of CuI normally used can be reduced so that homocoupling is minimized.

Synthesis of 5-(2-methoxy-1-naphthyl)- and 5-[2-(methoxymethyl)-1-naphthyl]-11H-benzo[b]fluorene as 2,2'-disubstituted 1,1'-binaphthyls via benzannulated enyne–allenes

“…1-Iodo-2-[2-(trimethylsilyl)ethynyl]benzene was prepared by treatment of 1-bromo-2-[2-(trimethylsilyl)ethynyl]benzene in THF with n -butyllithium at −78 °C followed by treatment with iodine [7]. 1-Ethynyl-2-iodo-benzene ( 15 ) [30] was prepared in quantitative yield by desilylation of 1-iodo-2-[2-(trimethylsilyl)ethynyl]benzene with sodium hydroxide in methanol. 1 - Ethynyl - 2 - (methoxymethyl)benzene ( 4b ) [31] and dimethyl (1-diazo-2-oxopropyl)phosphonate [32] were prepared according to the reported procedures.…”

Carboxylate‐Based, Room‐Temperature Ionic Liquids as Efficient Media for Palladium‐Catalyzed Homocoupling and Sonogashira–Hagihara Reactions of Aryl Halides

“…The efficient synthesis of [12]annulene and related derivatives in [bmim]BF 4 (bmim = 1-butyl-3-methylimidazolium) has been reported under Sonogashira conditions in the presence of CuI and [Pd(PPh 3 ) 4 ]. [18] The use of [bmim]PF 6 [19] and other ILs, such as butylpyridinium salts [20] (C 4 PyPF 6 , C 4 PyBF 4 , and C 4 PyNO 3 ), has also been described in copper-free, phosphane-assisted Sonogashira processes. This reaction was also conducted in [bbim]BF 4 , as solvent in the absence of a copper co-catalyst and a phosphane ligand but requires ultrasound irradiation.…”

Ionic liquids: a versatile medium for palladium-catalyzed reactions

“…Homocoupling was minimized under this reaction conditions. 155 Sonogashira coupling reaction of aryl iodides with terminal acetylenes (aromatic or aliphatic) proceeds efficiently in IL, [bmim][PF 6 ], using PdCl 2 (PPh 3 ) 2 as the catalyst (Scheme 36). This reaction works well in the absence of a copper salt.…”