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Under mild conditions, Beckmann rearrangement of a variety of ketoximes could proceed in the presence of chlorosulfonic acid using toluene as a solvent with excellent conversion and selectivity. This procedure could also be applied in the dehydration of aldoximes for obtaining the corresponding nitriles.

★★★★☆ D. Li et al. / Tetrahedron Letters 46 (2005) 671–674.

9-beta-D-Arabianofuranosyl guanine (6) and 2-amino-9-(beta-D-arabianofuranosyl)purine (8) were prepared from 2-amino-6-chloro-9-(2,3,5-triphenylmethoxyl-p-D-arabianofuranosyl)purine (4), a key intermediate which was stereoselectively prepared from 2,3,5-triphenylmethoxyl-D-arabianofuranose and 2-amino-6-chloro-purine. The yield of the intermediate was obviously improved and only P-isomer was formed by using the activated molecular sieve as environmental friendly catalyst, overcoming the defect that a 1: 1 mixture of alpha- and beta-isomers was formed, which was difficult to separate, when toxic mercury cyanide was previously used as catalyst.

★★★☆☆ X.-J. Yu et al. / Bioorg. Med. Chem. Lett. 15 (2005) 683–685.

A new kind of silica gel confined ionic liquid containing a metal complex as heterogenized catalysts was prepared for the carbonylation of amines and nitrobenzene without molecular oxygen to afford the corresponding ureas with greatly enhanced catalytic activity (TOF exceeded 11000mol.mol(-1). h(-1)), with a much lower amount of ionic liquids being needed, with easy catalyst separation and possible reusability, and avoidance of the using of explosive CO + O-2 gas mixtures. Such an enhancement in catalytic activity may be derived from the effect of a high concentration of ionic liquid containing a metal complex due to the confinement into the nanopores or cavities of the silica gel matrix.

★★★☆☆ Keywords: amines; carbonylation; ionic liquids; nitrobenzene; phosgene-free

★★★☆☆ Adv. Synth. Catal. 2005, 347, 225 –230.

★★★★★ J. AM. CHEM. SOC. 2005, 127, 4182-4183. ★★★★★

Beckmann rearrangement of several oximes catalyzed by metaboric acid was studied in room temperature ionic liquids. Especially for conversion of cyclohexanone oxime into e-caprolactam, excellent conversion and selectivity were obtained.

★★★☆☆ Keywords: Beckmann rearrangement; Oxime; Metaboric acid; Ionic liquid

★★★☆☆ S. Guo, Y. Deng / Catalysis Communications 6 (2005) 225–228.

Four non-chloroaluminate acidic ionic liquids have been used as catalysts for Pechmann condensations of phenols under solvent-free conditions. SO3H-functionalized trifluoromethanesulfonate imidazolium ionic liquid has proved to be the most active catalyst. Ionic liquid loads as low as 5 mol % can be used leading to high yields with activated phenols at an oil bath temperature of 80 degrees C. The acidities of the four ionic liquids have also been tested using the Hammett method in dichloromethane. The results are consistent with their catalytic activities as observed in the Pechmann reaction of resorcinol. This methodology offers significant improvements for the synthesis of coumarins with regard to yield of products, simplicity in operation, and green aspects by avoiding toxic catalysts and solvents.

★★★☆☆ Keywords: acid catalysis; coumarins; determination of acidity; ionic liquids; Pechmann condensation

★★★☆☆ Adv. Synth. Catal. 2005, 347, 512– 516.

Several novel sulfonyl chloride functionalized ionic materials were used as media and catalysts for Beckmann rearrangement of cyclohexanone oxime and satisfactory results were achieved under mild conditions. The effects of all parameters were discussed. Moreover, the deactivation of ionic liquid catalytic system during the recycle was investigated by using FTIR spectroscopy and mass balance calculation. The trapping of acidic ionic material with basic product is proved to be mainly responsible for the difficulties encountered in the reuse of this type of material. A possible mechanism was conjectured.

★★★☆☆ Keywords: Beckmann rearrangement; Cyclohexanone oxime; Caprolactam; Sulfonyl chloride functionalized ionic materials; IR investigation

★★★☆☆ Z. Du et al. / Journal of Molecular Catalysis A: Chemical 237 (2005) 80–85.

The carbonylation of amines with propargylic alcohol using CO2 as carbonyl source to yield N-substituted 4-methylene-2-oxazolidinones could efficiently proceed in ionic liquids, and various 4-methylene oxazolidinones with high yields could be obtained under relatively mild conditions. This result showed that ionic liquid might be an effective catalyst and reaction medium for the activation of CO2, which also offered a new way to the chemical fixation of CO2.

★★★★☆ Q. Zhang et al. / Tetrahedron Letters 46 (2005) 5907–5911.

The reactions of propargylic alcohols, aliphatic primary amines, and CO2 were conducted in CuCl/[BMIm]BF4 system to produce the corresponding 5-methylene-1,3-oxazolidin-2-ones under relatively mild conditions. The products could be conveniently isolated by means of liquid-liquid extraction. The solvent ionic liquid as well as CuCl catalyst can be recovered and reused three times without appreciable loss of activity. By this green approach, several new 5-methylene-1,3-oxazolidin-2-ones were prepared in excellent yields and purity and were well-characterized.

★★★★☆ J. Org. Chem. 2005, 70, 7376-7380.

A new concept of designing and synthesizing highly dispersed ionic-liquid catalysts was developed through physical confinement or encapsulation of ionic liquids (with or without metal complex) in a silica-gel matrix through a sol-gel process. We studied ionic liquids such as EMImBF4, BuMImBF4, DMImBF4, CMImBF4, BuMImPF6, either with or without [Pd(PPh3)2Cl2] and [Rh(PPh3)3Cl], in a silica-gel matrix (E=ethyl, Bu=butyl M=methyl, D=decyl, C=cetyl and Im=imidazolium). The contents of ionic liquids and loadings of Pd or Rh were 8-53 wt % and 0.10.15 wt %, respectively. Analyses of FT-Raman spectra showed that abnormal Raman spectra of the confined ionic liquids were observed in comparison with the bulk and pure ionic liquids. EMImBF4 and BuMImBF4 ionic liquids could be completely washed out from the silica-gel matrix under vigorous reflux conditions, but ionic liquids with larger molecular size, for example, DMImBF4 or CMImBF4, could be confined into the silica-gel nanopores relatively firmly. These results suggested that the ionic liquids were physically confined or encapsulated into the silica gel. The N2 adsorption measurements indicated that the silica-gel skeleton was mesoporous with 50-110 ? pore size after the BuMImBF4 ionic liquid was removed completely. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis showed that the silica-gel matrix was amorphous and non-uniformly mesoporous. Carbonylation of aniline and nitrobenzene for synthesis of diphenyl urea, carbonylation of aniline for synthesis of carbamates, and oxime transformation between cyclohexanone oxime and acetone were used as test reactions for these catalysts. Catalytic activities were remarkably enhanced with much lower amounts of ionic liquids needed with respect to bulk ionic-liquid catalysts or silica-supported ionic-liquid catalysts prepared with simple impregnation, in which the ionic liquid may be deposited as a thin layer on the support. Such unusual enhancement in catalytic activities may be attributed to the formation of nanoscale and high-concentration ionic liquids due to the confinement of the ionic liquid in silica gel; this results in unusual changes in the symmetry and coordination geometry of the ionic liquids.

★★★★☆ Keywords: carbonylation · catalysis· ionic liquids · nanotechnology ·synthesis design

★★★★☆ Chem. Eur. J. 2005, 11, 5279 – 5288