Deprotection of t-butyldimethylsilyl ethers promoted by cerium(IV) triflate

Bartoli, Giuseppe; Cupone, Giovanna; Dalpozzo, Renato; Nino, Antonio De; Maiuolo, Loredana; Procopio, Antonio; Sambri, Letizia; Tagarelli, Antonio

doi:10.1016/s0040-4039(02)01254-6

Cited by 47 publications

(11 citation statements)

References 15 publications

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“…Recently, the relative Lewis acidities of lanthanoid (III) triflates were evaluated by means of tandem mass spectrometry [4], and taking advantage from that, some of us studied the catalytic effect of erbium and cerium triflate, exhibiting pK h and WERC [5][6][7][8][9][10][11][12][13][14] values in accordance to Kobayashi statement. The role of the lanthanide cations in the catalytic activity of the corresponding triflates has not yet been fully clarified.…”

Section: Introductionmentioning

confidence: 99%

Principal properties (PPs) for lanthanide triflates as Lewis‐acid catalysts

Fortuna

Musumarra

Nardi

et al. 2006

Journal of Chemometrics

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A multivariate insight into lanthanide triflates descriptors allowed derivation of three principal properties (PPs). The first one resembling the lanthanide sequence in the periodic table, the second one reflecting the discontinuity in lanthanides properties, the so called 'gadolinium break', and the third one related to the change of coordination number of Ln ions in aqueous solution from nine to eight around Sm-Gd. Experimental support to the predicting ability of the above PPs as descriptors in the prediction of the yields for the synthesis of a-tocopherol from a selected set of four triflate catalysts (La, Eu, Er, Lu) was provided, opening new horizons for a rational selection in multivariate experimental design of Ln triflates catalysed organic reactions.

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Section: Introductionmentioning

confidence: 99%

Principal properties (PPs) for lanthanide triflates as Lewis‐acid catalysts

Fortuna

Musumarra

Nardi

et al. 2006

Journal of Chemometrics

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“…On the contrary, reaction of 29 with CuBr 2 /PhCOCl furnished the corresponding alcohol 31 [9] instead of its benzoate in good yield ( Table 2, Chemoselective deprotective acetylation between aliphatic and aromatic TBDMS ethers was also investigated. However, no selectivity in the deprotection was confirmed in the reaction of di-TBDMS ether of 3-(2-hydroxyphenyl)-1-propanol (34) [16] with 30 mol% of CuBr 2 at ambient temperature when a mixture of 3-(2-hydroxyphenyl)-1-propanol (35) and 3-(2-tert-butyldimethylsilyloxyphenyl)-1-propanol (36) was isolated in 80% and 17% yields respectively ( Table 2, entry 5).…”

Section: Resultsmentioning

confidence: 99%

CuBr2 Catalyzed One-Pot Transprotection of TBDMS Ethers to Acetates/benzoates: Chemoselective Acetylation of Aliphatic in the Presence of Aromatic TBDMS Ethers

Bhatt¹,

Nayak

2008

LOC

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A variety of TBDMS ethers were directly transprotected into their acetates/benzoates with acetyl chloride/benzoyl chloride in a one-pot procedure using CuBr 2 (30 mol%). Chemo-selective transprotection of aliphatic TBDMS ethers in the presence of aromatic TBDMS ethers was achieved using 10 mol% of the catalyst. Various sensitive functional groups such as ketals, ketones, alkenes, allyl and benzyl ethers were found to be compatible under the reaction conditions.

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“…Tetramethylethylenediamine 4 , tertiary phosphines 5 , carbon tetrabromide in ethyl acetate 6 , p-toluenesulfonic acid 7 , zinc chloride 8 , iodine 9 , sulfamic acid 10 , magnesium bromide 11 , cobalt chloride 12 , tantalum chloride 13 , La(OPr-i)3 14 , silica gel-supported sodium hydrogen sulfate 15 , montmorillonite K-10 and KSF 16 , alumina 17 , yttria zirconia with acetic acid 18 , Ac2O-pyridine/basic alumina under microwave irradiation 19 , KF-Al2O3 with Ac2O/AcCl 20 , vanadyl(V) acetate 21 , distannoxane 22 , zeolite HSZ-360 23 , Pseudo-monas cepacia PS lipase adsorbed on Celite 24 , and twisted amides 25 have also been applied for the acetylation of alcohols and phenols. Another important development has been the introduction of trifluorme-thanesulfonate derivatives, such as TMSOTf 26 , Yb-(OTf)3 27 , Cu(OTf)2 28 , Sc(OTf)3 29 , In(OTf)3 30 , Bi(OTf)3 31 , cerium(III) 32 and (IV) 33 salts as efficient catalysts in acetylation with acetic acid, or anhydride or acetyl chloride. All these ways lead to wastes as well as some reactions involving solvents, often toxic, polluting and longer time.…”

Section: Introductionmentioning

confidence: 99%