Graphene oxide‐bound electron‐deficient tin(IV) porphyrin: a highly efficient and selective catalyst for trimethylsilylation of alcohols and phenols with hexamethyldisilazane

The catalytic activity of graphene oxide‐bound tetrakis(p ‐aminophenyl)porphyrinatotin(IV) trifluoromethanesulfonate, [Sn^IV(TNH₂PP)(OTf)₂], in the trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) is reported. The prepared catalyst was characterized using inductively coupled plasma analysis, scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared and diffuse reflectance UV–visible spectroscopies. This heterogeneous catalyst was used for selective trimethylsilylation of various alcohols and phenols with HMDS in short reaction times and high yields. Also, the catalyst is of high reusability and stability, in that it was recovered several times without loss of its initial activity. The chemoselectivity of this catalytic system in the silylation of primary alcohols in the presence of secondary and tertiary alcohols and also phenols was investigated.     

Mild and efficient silylation of alcohols and phenols with HMDS using Bi(OTf)3 under solvent-free condition

A very efficient and mild silylation of alcohols and phenols with hexamethyldisilazane (HMDS) at rt is developed using Bi(OTf)₃ as the catalyst. Primary, secondary and tertiary alcohols as well as phenols are excellently converted into corresponding TMS ethers in a very short reaction time. This procedure can also be applied to large scale silylation for industrial application.     

Rapid,highly efficient and chemoselective trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) catalyzed by reusable electron‐deficient tin(IV)porphyrin

In this paper, rapid and highly efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) in the presence of catalytic amounts of high‐valent [Sn^IV(TPP)(OTf)₂] is reported. This catalytic system catalyzes trimethylsilylation of primary, secondary and tertiary alcohols as well as phenols, and the corresponding TMS‐ethers were obtained in high yields and short reaction times at room temperature. It is noteworthy that this method can be used for chemoselective silylation of primary alcohols in the presence of secondary and tertiary alcohols and phenols. The catalyst was reused several times without loss of its catalytic activity. Copyright © 2009 John Wiley & Sons, Ltd.     

Highly efficient chemo- and regioselective silylation of -OH groups and cyanosilylation of aldehydes promoted by TiCl2(OTf)-SiO2 as a new recyclable catalyst

TiCl₂(OTf)-SiO₂ as an easy handling recyclable catalyst was applied for trimethylsilylation of diethyl α-hydroxyphosphonates, alcohols and phenols with high selectivity using HMDS as a silylating agent. Cyanotrimethylsilyl ethers were also obtained in excellent yields from treatment of aldehydes with TMSCN in the presence of this catalyst.     

[Sn(TPP)(BF4)2]: An efficient and reusable catalyst for chemoselective trimethylsilylation of alcohols and phenols with hexamethyldisilazane

Tin(IV)tetraphenylporphyrinato tetrafluoroborate, [Sn^IV(TPP)(BF₄)₂], was used as an efficient catalyst for trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS). High-valent [Sn^IV(TPP)(BF₄)₂] catalyzes trimethylsilylation of primary, secondary and tertiary alcohols as well as phenols, and the corresponding TMS-ethers were obtained in high yields and short reaction times at room temperature. While, under the same reaction conditions [Sn^IV(TPP)Cl₂] is less efficient to catalyze these reactions. One important feature of this catalyst is its ability in the chemoselective silylation of primary alcohols in the presence of secondary and tertiary alcohols and phenols. The catalyst was reused several times without loss of its catalytic activity.     

High-valent [Sn(Br8TPP)(OTf)2] as a highly efficient and reusable catalyst for selective methoxymethylation of alcohols and phenols: The effect of substituted bromines on the catalytic activity

High-valent tin(IV)octabromotetraphenylporphyrinato trifluoromethanesulfonate, [Sn^IV(Br₈TPP)(OTf)₂], was used for selective methoxymethylation of alcohols and phenols with formaldehyde dimethyl acetal (FDMA) at room temperature. Different primary, secondary and tertiary alcohols as well as phenols were converted to their corresponding methoxymethyl ethers with FMDA in the presence of an electron deficient tin(IV) porphyrin. The catalyst was reused several times without significant loss of its activity.     

RuIII(OTf)SalophenCH2–NHSiO2–Fe: an efficient and magnetically recoverable catalyst for trimethylsilylation of alcohols and phenols with hexamethyldisilazane

Efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) catalyzed by ruthenium(III) complex of chloromethylated Salophen supported on nanomagnetic materials is reported. First, the iron nanomagnets were silica coated, functionalized with amine and then ruthenium CM‐Salophen was successfully bonded to their surface. The catalyst, Ru^III(OTf)SalophenCH₂–NHSiO₂–Fe, was characterized by elemental analysis, FT‐IR and UV–visible spectroscopic techniques, transmission electron microscopy and inductively coupled plasma (ICP). The Ru^III(OTf)SalophenCH₂–NHSiO₂–Fe catalyzed trimethylsilylation of primary and secondary alcohols as well as phenols, and the corresponding TMS ethers were obtained in high yields and short reaction times at room temperature. This new heterogenized trimethylsilylation catalyst is easily recovered with a magnet and showed no appreciable loss of activity even after five consecutive runs. Copyright © 2014 John Wiley & Sons, Ltd.     

Polystyrene‐Gallium Trichloride Complex: A Mild,Highly Efficient,and Recyclable Polymeric Lewis Acid Catalyst for Chemoselective Silylation of Alcohols and Phenols with Hexamethyldisilazane

Polystyrene‐supported gallium trichloride (PS/GaCl₃) as a highly active and reusable heterogeneous Lewis acid effectively activates hexamethyldisilazane (HMDS) for the efficient silylation of alcohols and phenols at room temperature. In this heterogeneous catalytic system, primary, secondary, and tertiary alcohols as well as phenols were converted to their corresponding trimethylsilyl ethers with short reaction times and high yields under mild reaction conditions. The heterogenized catalyst is of high reusability and stability in the silylation reactions and was recovered several times with negligible loss in its activity or a negligible catalyst leaching, and also there is no need for regeneration. It is noteworthy that this method can be used for chemoselective silylation of different alcohols and phenols with high yields.     

Selective tetrahydropyranylation of alcohols and phenols using titanium(IV) salophen trifluoromethanesulfonate as an efficient catalyst

Titanium(IV) salophen trifluoromethanesulfonate, [Ti^IV(salophen)(OSO₂CF₃)₂], as a catalyst enables selective tetrahydropyranylation of alcohols and phenols with 3,4‐dihydro‐2H‐pyran. Using this catalytic system, primary, secondary and tertiary alcohols, as well as phenols, were converted to their corresponding tetrahydropyranyl ethers in high yields and short reaction times at room temperature. Investigation of the chemoselectivity of this method showed discrimination between the activity of primary alcohols in the presence of secondary and tertiary alcohols and phenols. This heterogenized catalyst could be reused several times without loss of its catalytic activity. Copyright © 2016 John Wiley & Sons, Ltd.     

Highly efficient protection of alcohols and phenols catalysed by tin porphyrin supported on MIL‐101

The catalytic activity of 5,10,15,20‐tetrakis(4‐aminophenyl)porphyrinatotin(IV) trifluoromethanesulfonate, [Sn^IV(TNH₂PP)(OTf)₂], supported on chloromethylated MIL‐101, was investigated in the trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) and also their tetrahydropyranylation with 3,4‐dihydro‐2H‐pyran. Excellent yields, mild reaction conditions, short reaction times and reusability of the catalyst without significant decrease in its initial activity are noteworthy advantages of this supported catalyst. Copyright © 2015 John Wiley & Sons, Ltd.     

Green and Efficient Procedure for the Trimethylsilylation of Hydroxy Groups and Their Regeneration Using Sulfamic Acid as Recyclable Catalyst

Structurally diverse alcohols and phenols were efficiently transformed into their corresponding trimethylsilyl ethers with hexamethyldisilazane (HMDS) in the presence of catalytic amounts of sulfamic acid (SA) at room temperature under both acetonitrile and solvent-free conditions. Deprotection of these trimethylsilyl ethers to their parent alcohols and phenols was also achieved using this catalyst in water at room temperature.     

Cross‐linked poly(4‐vinylpyridine/styrene) copolymer‐supported bismuth(III) triflate: an efficient heterogeneous catalyst for silylation of alcohols and phenols with HMDS

Cross‐linked poly(4‐vinylpyridine/styrene) copolymer‐supported bismuth(III) triflate (³⁰P/S‐Bi) effectively activates hexamethyldisilazane (HMDS) for the silylation of alcohols and phenols. By the use of this heterogeneous catalytic system, a wide range of alcohols as well as phenols are converted into their corresponding trimethylsilyl ethers in high yield under mild reaction conditions. The catalyst was reused more than 10 times without significant loss of its catalytic activity. Copyright © 2011 John Wiley & Sons, Ltd.     

Highly efficient and chemoselective trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) catalyzed by reusable electron-deficient [Ti(salophen)(OTf)2]

In the present work, highly efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) catalyzed by high-valent [Ti^IV(salophen)(OTf)₂] is reported. Under these conditions, primary, secondary and tertiary alcohols as well as phenols were silylated in short reaction times and high yields. It is noteworthy that this method can be used for chemoselective silylation of primary alcohols in the presence of secondary and tertiary alcohols and phenols. The catalyst was reused several times without loss of its catalytic activity.     

Highly efficient tetrahydropyranylation of alcohols and phenols catalyzed by a new and reusable high-valent vanadium(IV) porphyrin

In the present work, the catalytic activity of high-valent tetraphenylporphyrinatovanadium(IV) trifluoromethanesulfonate, [V^IV(TPP)(OTf)₂], in the tetrahydropyranylation of alcohols and phenols with 3,4-dihydro-2H-pyran (DHP) is reported. This new electron-deficient V(IV) compound was used as a highly efficient catalyst for pyranylation of primary (aliphatic and benzylic), sterically-hindered secondary and tertiary alcohols with DHP. Tetrahydropyranylation of phenols with DHP was also performed to afford the desired THP-ethers. The chemoselectivity of this method was also investigated. The results indicated that primary alcohols are more reactive in the presence of secondary and tertiary alcohols and phenols. This catalyst was reused several times without loss of its activity.     

无催化剂下醇和酚的高效O-硅基化

硅醚类化合物广泛应用于有机合成、 分离分析和精细化工等领域. 六甲基二氮硅烷是近年来发展的一种新型硅基化试剂, 被用于硅醚的高效合成, 但由于六甲基硅烷较为惰性, 通常需要加入催化剂活化. 本文报道了一种无催化剂下醇、 酚的高效硅基化新方法. 研究结果表明, 该方法可以兼容一级苄醇、 杂芳基苄醇、 脂肪醇, 二级醇甚至三级醇, 多数反应可以实现定量转化, 无需柱层析即可实现产物的分离纯化. 该方法可以拓展到酚的高效硅醚化, 也可以很方便地放大到100 mmol, 收率达到99%, 表明该方法具有较好的实用价值.     

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

Herein, we want to report a simple and convenient way for protection‐deprotection of alcohols in the presence of ammonium decatungstocerate(IV) {(NH₄)₈[CeW₁₀O₃₆]·20H₂O} as catalyst under ambient temperature in CH₃CN. Using 0.002 mmol of the catalyst, various alcohols and phenols were transformed easily to the corresponding TMS ethers in excellent yields. In the second part, various TMS ethers were successfully converted to the parent hydroxyl compounds in the presence of the ammonium decatungstocerate(IV) catalyst. Copyright © 2010 John Wiley & Sons, Ltd.     

Vanadium Hydrogen Sulfate (I): Chemoselective Trimethylsilylation of Alcohols and Deprotection of Trimethylsilyl Ethers

Trimethylsilylation of alcohols with hexamethyldisilazane (HMDS) catalyzed by V(HSO₄)₃ under mild and completely heterogeneous reaction condition is reported. The method is highly chemoselective for the protection of alcohols in the presence of phenols, amines and thiols. Also, the deprotection of trimethylsilyl ethers is performed in the presence of V(HSO₄)₃ at room temperature in good to high yields.     

Trimethylsilylation of Hydroxyl Group with 1,1,1,3,3,3‐Hexamethyldisilazane (HMDS) Catalyzed by Tribromomelamine (TBM)

Tribromomelamine (TBM) can be used as a novel catalyst for the trimethylsilylation of alcohols and phenols with 1,1,1,3,3,3‐hexamethyldisilazane (HMDS). A wide variety of hydroxyl groups were selectively protected in CH₂Cl₂/CH₃CN under mild conditions.     

Poly(4-vinylpyridine) catalyzed chemoselective O-TMS protection of alcohols and phenols and N-Boc protection of amines

Poly(4-vinylpyridine) (PVP) acts as an efficient and reusable catalyst for the selective and efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) and N-tert-butoxycarbonylation of amines with (Boc)₂O. All reactions were performed under mild conditions in good to high yields.     

A Mild and Highly Efficient Method for the Preparation of Silyl Ethers using Fe(HSO4)3/Et3N by Chlorosilanes

A very efficient and mild procedure for preparation of silyl ethers from benzylic, allylic, propargilic alcohols, phenols, naphtoles and some of phenolic drugs with trimethylsilylchloride (TMSCl), triethylsilylchloride (TESCl) and t‐buthyldimethylsilyl chloride (TDSCl) ethers in the presence of Fe(HSO₄)₃/Et₃N in room temperature in excellent yields is reported. This procedure also allows the excellent selectivity for silylation of alcohols and phenols.