Facile and Highly Selective Deprotection of tert‐Butyldimethyl Silyl Ethers using Sulfated SnO₂ as a Solid Catalyst

Application of Sulfated Tin (IV) Oxide Solid Superacid Catalyst to Partial Coupling Reaction of α-Pinene to Produce Less Viscous High-Density Fuel

“…When compound 11 or 12 reacted under this condition as a sole starting material, the chemical equilibrium consisted of only compounds 11, 12, 15, and a small amount of p-mentha-3,8-diene (20), where stabilization by the formation of a conjugated diene was considered the driving Scheme 1. Plausible mechanism of isomerization of α-pinene over sulfated tin oxide catalyst: α-pinene (1); pinanyl cation (2); bornanyl cation (3); tricyclene (4); isocamphanyl cation (5); camphene (6); p-mentha-1-en-8-yl cation (7); p-mentha-1-en-4-yl cation (8); limonene (9); terpinolene (10); α-terpinene (11); γ-terpinene (12); p-mentha-4(8)-en-2-yl cation (13); allylic carbocation I (14); isoterpinolene (15); allylic carbocation II (16); p-mentha-2-en-8-yl cation (17); allylic carbocation III (18); p-mentha-3-en-1-yl cation (19); p-mentha-3,8-diene (20); p-cymene (21); p-menthene isomers (22a-c).…”

“…However, this suggestion has been controversial considering various isoterpinolene/terpinolene concentration ratios, either higher or lower than 1 [37]. A second possible mechanism is initiated by protonation of α-terpinene (11) or γ-terpinene (12), which gives allylic carbocation III (18) and p-mentha-3-en-1-yl cation (19). This proposal was supported by Salacinski's results which showed the chemical equilibria of p-menthadiene species under sulfuric acid at 67 • C [38].…”

“…Herein, we used sulfated tin(IV) oxide (SO 4 2− /SnO 2 ) as a solid superacid catalyst to carry out partial coupling of α-pinene for the production of less viscous high-density fuel molecules. SO 4 2− /SnO 2 catalysts have been used in various types of organic reactions, such as dehydration of sorbitol and xylose to isosorbide and furfural, respectively, esterification of free fatty acids, the Penchmann condensation reaction, and deprotection of silyl ether groups [15][16][17][18][19]. Successive chemical precipitation and immersion in diluted sulfuric acid yielded this catalyst from tin chloride pentahydrate in a facile procedure.…”

Rapid and efficient protection of alcohols and phenols, and deprotection of trimethylsilyl ethers catalyzed by a cerium‐containing polyoxometalate

“…Deprotection of TMS ethers to their corresponding alcohols under mild reaction conditions is of practical importance and several methods and catalysts such as bismuth(III) salts, [23] NaBrO 3 -NH 4 Cl, [24] PhCH 2 PPh 3 HSO 5 , [25] Zr(KPO 4 ) 2 , [26] potassium dodecatungstocobaltate(III) trihydrate, [27] cobalt(II) tetrasulfophthalocyanine, [28] trimethylsilyl bromide, [29] CuBr 2 , [30] tetraethylammonium superoxide, [31] DABCO-bromine, [32] sulfated SnO 2 [33] and LiOAc [34] have been reported for this transformation. However, in some of the reported methods one or more disadvantages, such as harsh reaction conditions, high reaction temperatures, long reaction times, high cost or toxicity of the reagents have been experienced.…”

A mild and chemoselective method for the deprotection of tert-butyldimethylsilyl (TBDMS) ethers using iron(III) tosylate as a catalyst

“…Several alternative methods have also been developed for the deprotection of TBDMS ethers. These include Selectfluor (10.0 mol %), 4 LiOAc (20.0 mol %), 5 pyridinium tribromide (Py·Br 3 ) (5.0-100.0 mol %), 6 ZrCl 4 (20.0 mol %), 7 tris( 4-bromophenyl )aminium hexachloroantimonate (TBPA + ·SbCl 6 -) (5.0-10.0 mol %), 8 sulfated Sn0 2 (1.0% by weight ), 9 silica supported NaHS0 4 , lOTiCl4-Lewis base complexes (1.2 equiv), 11 sulfonic acid-functionalized nanoporous silica, 12 phosphomolybdic acid, 13 NiCb in 1,2-ethanediol (20.0 mol %), 14 19 ceric ammonium nitrate (10.0 mol %), 20 tetrabutylammonium tribromide (10.0 mol %), 21 TMSOTf (2.0 equiv), 22 Zn(BF 4 h (4.0 equiv), 23 and DMSO-H 2 0 (excess DMSO) 24 Methods for the de protection of TBDMS ethers under acidic conditions have also been developed. These include aqueous HF, 25 CF 3 COOH/H 2 0 (9:1), 26 and CH 3 COOH in aqueous THF (13:7:3 ).…”