TMS·OTf-Catalyzed α-bromination of carbonyl compounds by N-bromosuccinimide

Various carbonyl compounds undergo α-bromination reaction under a mild and practical condition utilizing N-bromosuccinimide (NBS), catalyzed by trimethylsilyl trifluoromethanesulfonate (TMS·OTf). This method is also effective for the side-chain bromination of heteroaromatic carbonyl compounds without the ring brominations.     

Convenient preparation of cyclic acetals,using diols,TMS-source,and a catalytic amount of TMSOTf

With use of diol, alkoxysilane, and a catalytic amount of trimethylsilyl trifluoromethanesulfonate (TMSOTf), carbonyl compounds are converted to acetals in good yields under mild conditions. This procedure, which was carried out without synthesizing the silylated diols, is a more convenient adaptation of Noyori's method. This acetalization applies to not only simple but also conjugated carbonyl compounds. Moreover, various TMS compounds, including solid supported compounds, are effective for this method instead of alkoxylsilane.     

Reissert compound studies. LXIV. Reissert compound and other products from an isolated N-benzoylisoquinolinium triflate salt

In the presence of trimethylsilyl trifluoromethanesulfonate, a methylene chloride solution of isoquinoline and benzoyl chloride gave N-benzoylisoquinolinium triflate ( 3 ) and N-H-isoquinolinium triflate ( 4 ). Depending on the reaction conditions, reaction of 3 may occur on the isoquinoline ring yielding a Reissert compound and 1,2-dihydroisoquinoline species. Otherwise, reactions transpire on the carbonyl of 3 to give an amide, an ester, and an anhydride.     

Studies on imidazole derivatives and related compounds. 3. Regioselective glycosylation of 4-carbamoylimidazolium-5-olate

In the synthesis of glycosyl derivatives of 4-carbamoylimidazolium-5-olate ( 2 ) by the silyl-Hilbert-Johnson method using trimethylsilyl trifluoromethanesulfonate as catalyst, we obtained N-3 nucleosides 5 as major products and N-1,N-bis-nucleosides 6 as minor ones. The desired N-1 nucleosides 4 were isolated in only low yields. However, the yields of 4 were improved by adding ca. One equivalent of stannic chloride to the silylated 4-carbamoylimidazolium-5-olate ( 3 ). On the basis of nuclear magnetic resonance (¹³C and ²⁹Si) and ultraviolet spectroscopic studies, we verify the formation of σ-complexes between the silylated base 3 and the Lewis acid (stannic chloride or trimethylsilyl trifluoromethanesulfonate), and the propose the structures of these complexes and the reaction mechanism.     

Silyl trifluoromethanesulfonate-activated para-methoxybenzyl methyl ether as an alkylating agent for thiols and aryl ketones

para-Methoxybenzyl methyl ether acts as an alkylating agent for thiols in the presence of trimethylsilyl trifluoromethanesulfonate and trialkylamine base in good yields (58–96%). Aryl ketones are alkylated under similar conditions, probably through an enol silane intermediate, also in high yields (67–95%). The active alkylating species is likely a p-methoxybenzyl cation.     

The Activation of Imines to Nucleophilic Attack by Grignard Reagents

The reaction of trimethylsilyl trifluoromethanesulfonate (trimethylsilyl triflate, TMSOTf) with imines leads to the formation of N-trimethylsilyliminium salts which react efficiently with soft nucleophiles to form secondary amines.     

Regio- and stereodefined synthesis of trimethylsilyl enol ethers resulted from the isomerization of α-trimethylsilyl ketones

The isomerization of an α-trimethylsilyl ketone is lead to the corresponding trimethylsilyl enol ether with the enhanced regioselectivity by heating or by the assist of trimethylsilyl trifluoromethanesulfonate. The thermal reaction discloses a new regiodefined (E)-selective route to silyl enol ethers.     

Synthesis and Reactivity of the New Trimethylsilyl Esters of Aminomethylenebisorganophosphorus Acids

The interaction of trimethylsilyl esters of trivalent organophosphorus acids containing PH and POSiMe₃ fragments in the presence of trimethylsilyl trifluoromethanesulfonate as catalyst is proposed as a convenient method for the synthesis of new trimethylsilyl esters of aminomethylenebisorganophosphorus acids with three and four coordinated phosphorus. Also the new functionalized derivatives of the aminomethylenebisphosphinic acids with substituted hydroxymethyl moieties are synthesized, and some properties of the obtained compounds are presented.     

Trimethylsilyl trifluoromethanesulfonate as a catalyst of the reaction of allyltrimethylsilane and acetals

In the presence of a catalytic amount of trimethylsilyl trifluoromethanesulfonate, allyltrimethylsilane reacts with acetals to give the corresponding homoallyl ethers in high yields.     

A facile procedure for acetalization under aprotic conditions

Carbonyl compounds are readily acetalized by alkoxysilanes in the presence of trimethylsilyl trifluoromethanesulfonate catalyst.     

Synthesis of the New Types of N‐Unsubstituted Aminomethylenebisorganophosphorus Acids and Their Derivatives

The interaction of trimethylsilyl esters of trivalent organophosphorus acids containing PH and POSiMe₃ groups with hydrochlorides of ethoxymethylene imines is a convenient method for the synthesis of new trimethylsilyl esters of N‐unsubstituted aminomethylenebisorganophosphorus acids with three and four coordinated phosphorus. Also trimethylsilyl trifluoromethanesulfonate as effective catalyst is used for the similar interaction of hydrochlorides of ethoxymethylene imines with tris(trimethylsilyl)phosphite. The corresponding bisorganophosphorus acids and their derivatives are presented.     

Stereo- and regio-controlled aldol synthesis

Treatment of (Z)-trimethylsilyl enol ethers with dibutylboryl trifluoromethanesulfonate followed by removal of trimethylsilyl triflate generated and addition of aldehydes affords the corresponding erythro aldols with almost complete stereo- and regio-selectivities.     

Synthesis of new functionalized aryl‐substituted methylphosphonic and methylenediphosphonic acids and their derivatives

The convenient syntheses of new aryl‐substituted hydroxymethylphosphonic and methylenediphosphonic acids from the aromatic aldehydes, their derivatives, and phosphorous acid esters in the presence of the effective catalysts (trimethylsilyl trifluoromethanesulfonate, zinc chloride, and cadmium iodide) were developed.     

Lewis base catalyzed Mannich-type reactions between trimethylsilyl enol ethers and aldimines

Lewis base catalyzed Mannich-type reaction between trimethylsilyl enol ethers and N-tosylaldimines is described. Nitrogen anions generated from amides or imides such as lithium benzamide or potassium phthalimide are found to be effective Lewis base catalysts in DMF at room temperature to afford the corresponding beta-amino carbonyl compounds in good to high yields; the oxygen anion generated from carboxylic acids such as lithium acetate was also found to be effective in dry DMF. The above-mentioned lithium acetate-catalyzed Mannich-type reaction between aldimines and various trimethylsilyl (TMS) enol ethers such as silyl ketene acetal proceeded smoothly even in water-containing DMF. Then, Lewis base catalyzed three-component Mannich-type reactions of TMS enol ether, tosylamide, and aromatic aldehyde having electron-withdrawing group such as p-nitrobenzaldehyde were investigated. The reaction proceeded smoothly to afford the corresponding beta-amino ester in good yield. Further, ammonium carboxylates such as tetrabutyl ammonium acetate or tetrabutyl ammonium benzoate were found to be more effective Lewis base catalysts in the above-mentioned Mannich-type reaction. The synthesis proceeded in various solvents at lower temperatures. The reaction between aldimines and TMS enol ethers generated from thioester and various ketones such as propiophenone or cyclohexanone also proceeded smoothly to afford the corresponding beta-amino carbonyl compounds in high yields with good to high anti-selectivities.     

A New Strategy for the Stereoselecitve Syntheses of C-Glycosyl Compounds of β-Pentapyranoses

The C-glycosyl compounds of β-L-xylopyranose and β-D-arabinopyranose were conveniently prepared by reduction of methyl α-D-glucopyranoside and methyl α-D-mannopyranoside with triethylsilane in the presence of trimethylsilyl trifluoromethanesulfonate, respectively.     

A novel aminomethylation of silyl enol ethers with aminomethyl ethers catalyzed by iodotrimethylsilane or trimethylsilyl trifluoromethanesulfonate

The iodotrimethylsilane-catalyzed reaction of silyl enol ethers with aminomethyl ethers in acetonitrile gives aminomethylation products of the corresponding ketones readily. The reaction can slso be catalyzed by trimethylsilyl trifluoromethanesulfonate in dichloromethane.     

Benzylation of β-dicarbonyl compounds and 4-hydroxycoumarin using TMSOTf catalyst: a simple, mild, and efficient method

The direct benzylation of 1,3-dicarbonyl compounds and 4-hydroxycoumarin with a wide variety of benzylic alcohols was achieved using trimethylsilyl trifluoromethanesulfonate as an efficient catalyst. The reaction proceeded under very mild conditions at room temperature providing the desired products in good to excellent yields.     

Regiospecific synthesis of 6-halouridine derivatives: An effective method for coupling sterically hindered pyrimidine bases to ribose

6-Halouridine derivatives were synthesized regiospecifically through the coupling of N3-protected 6-halouracil to a ribose derivative. The combination of the silylating reagent N,O-bis(trimethylsilyl)acetamide and Lewis acid catalyst trimethylsilyl trifluoromethanesulfonate is unique in their ability to facilitate the coupling of sterically hindered pyrimidine bases to ribose to form nucleoside derivatives.     

A tandem enol silane formation-Mukaiyama aldol reaction mediated by TMSOTf

A slight excess of silyl trifluoromethanesulfonate mediates a tandem enol silane formation-Mukaiyama aldol reaction in the presence of Hunig’s base. Preformation of the enol silane is unnecessary for efficient reactions, which proceed in 75-97% yield for the addition of aryl methyl ketones and acetate esters to non-enolizable aldehydes. Mechanistic data suggests that free amine is crucial for full conversion.     

The synthesis of head-to-tail (H-T) dimers of 3-substituted thiophenes by the hypervalent iodine(III)-induced oxidative biaryl coupling reaction

The head-to-tail (H-T) dimers could be obtained selectively by the oxidative coupling reaction of 3-substituted thiophenes using a combination of hypervalent iodine(III) reagents and trimethylsilyl trifluoromethanesulfonate.