Benzylation of aromatics with PhCH 2 Cl and PhCH 2 OH is conveniently performed in [BMIM][OTf] or [BMIM][PF 6 ] ionic liquids (ILs), by using TfOH, Sc(OTf) 3 and Yb(OTf) 3 ?xH 2 O as catalysts. With PhCH 2 Cl, high conversions were achieved by using 20% Sc(OTf) 3 or Yb(OTf) 3 hydrate under mild conditions (65-80 uC). Triflic acid is superior to Yb(OTf) 3 as promoter for benzylation with PhCH 2 OH in the IL solvent, since in most cases little or no dibenzyl ether (DBE) was formed as side product. The scope of arene benzylation with benzyl alcohol in the TfOHcatalyzed and Yb(OTf) 3 -catalyzed reactions was examined in [BMIM][PF 6 ] solvent. Whereas conversions are typically quantitative at 65-70 uC, minor amounts of DBE were produced, along with the corresponding ArCH 2 Ph (with minor amounts of dibenzylated derivatives being detected in benzylation of mesitylene and biphenyl). Substrate selectivity (K T /K B ) and regioselectivity (isomer distribution) measured for benzylation in IL solvents employing TfOH or Yb(OTf) 3 as catalyst are similar to those reported previously in molecular solvents employing Nafion-H, AlCl 3 , TiCl 4 or ''clayzic''. The observed high yields and chemoselectivities (absence of DBE), coupled to easy isolation of the benzylated products and recycling/reuse of the IL, provide a new life for this classical transformation.

A mild and efficient process has been developed for the one-pot adamantylation of aromatic substrates employing 1-AdaOH, 1-AdaCl, 1-AdaBr, and 1-Br-3,5,7-trimethyladamantane as adamantylating agents, with triflic acid (TfOH) as promoter and n-butylmethylimidazolium triflate [BMIM][OTf] room temperature ionic liquid (IL) as solvent. The influence of reaction temperature, reaction time and the amount of TfOH was gauged in model reactions employing 1-AdaOH, 1-AdaCl and 1-AdaBr with toluene as the substrate. Under optimal conditions, the reactions exhibit high para selectivity with little or no adamantane side-product being formed. The synthetic scope of this transformation was tested for representative alkylbenzenes and haloalkylbenzenes. Comparative reactions carried out in 1,2-dichloroethane (DCE) produce increased amounts of the meta isomer and substantial amounts of adamantane. Substrate selectivities (K(T)/K(B)) were measured in competitive experiments in [BMIM][OTf] and in DCE as solvents. Isomerization tests were performed to shed light on the origin of the meta isomer. A DFT study was also conducted to compare relative stabilities of the isomeric products, to gauge the relative stabilities of the intermediate isomeric benzenium ions of adamantylation and their charge distribution modes, and to explore the intramolecular process for isomerization in the benzenium ion.

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Metallic triflates M(OTf)(3) (M = Bi, Sc, Yb), immobilized in imidazolium ionic liquids [BMIM][BF(4)], [BMIM][PF(6)] and [BMIM][OTf] are efficient systems for one-pot reactions of propargylic alcohols 1,3-diphenyl-2-propyn-1-ol Ia, 1-methyl-3-phenyl-2-propyn-1-ol Ib, and 2-pentyn-1-ol Ic, with a wide range of arenes bearing activating substituents, under mild conditions. The [BMIM][PF(6)]/B(C(6)F(5))(3) and [BMIM][PF(6)]/TfOH systems were superior in propargylation with Ib and Ic, while reaction of 3-phenyl-2-propyn-1-ol Id with activated aromatics resulted in the formation of diaryl-propanones instead. Propargylation of anisole with Ib under M(OTf)(3) catalysis is highly para selective, but with TfOH or B(C(6)F(5))(3) as catalyst the ortho isomer was also formed. Steric influence of the propargylic moiety on substrate selectivity is reflected in the lack of ortho propargylation for phenol and ethylbenzene by using propargylic alcohol Ia, and notable formation of the ortho isomer employing alcohol Ib. In the later case para selectivity could be increased by running the reaction at r. t. for 10 h. The Bi(OTf)(3)-catalyzed reaction of 1,3-dimethoxybenzene with Ia led to minor formation of dipropargylated derivative, along with the monopropargyl product. Propargylation of the less reactive arenes (mesitylene, ethylbenzene, toluene), using Sc(OTf)(3) as catalyst, led increasingly to the formation of dipropargylic ethers and propargyl ketones, with no ring propargylation product with toluene. Concomitant formation of dipropargylic ether was also observed in Yb(OTf)(3)-catalyzed propargylation of β-naphthol, whereas propargylation of 2-nitro and 4-nitro-aniline led to N-propargylation. The recycling/reuse of the IL was demonstrated in representative cases with no appreciable decrease in the conversions over 3 cycles. It was also shown that recycled IL could be used to propargylate a different aromatic compound. The efficacy of IL/M(OTf)(3) and IL/TfOH systems for cross-breeding two propargylic alcohols or a propargylic alcohol with a non-propargylic alcohol and/or self-coupling, to form a wide variety of functionalized ethers is also demonstrated.