Acids Trityl tetrafluoroborate

Trialkylaluminums, 204 Trichloroisopropoxytitanium, 300 Triisobutylaluminum, 205 Trimethylaluminum, 205 Trityl perchlorate, 339 Trityl tetrafluoroborate, 301 Zinc bromide, 349 Zinc chloride, 44, 108, 181, 190, 349 Zinc iodide, 88, 112, 280, 349, 350 Zirconium(IV) acetylacetonate, 351 Zirconium(IV) chloride, 16 Zirconium(IV) isopropoxide, 311 Other Organic and Inorganic Acids Acetic acid, 45 Benzoic acid, 312 Camphor-10-sulfonic acid, 62, 64 Formic acid, 137... 

They react with trityl tetrafluoroborate in acetonitrile or tetra-fluoroboric acid in acetic anhydride giving the 2-unsubstituted... 

Alkoxy- or 2-alkylthio-l,3-dithioles (119) are easily prepared. 264,26 5 They react with trityl tetrafluoroborate in acetonitrile or tetra-fluoroboric acid in acetic anhydride giving the 2-unsubstituted... 

Trityl tetrafluoroborate oxidizes secondary alcohols to ketones primary, secondary diols are selectively oxidized at the secondary position by this reagent. /Lt-Oxo-bis(chlorotriphenylbismuth) is a mild reagent for the oxidation of alcohols, and is particularly suitable for the oxidation of the hydroxy-group in allylic alcohols. Dichlorodicyanobenzoquinone (DDQ) with periodic acid in HCl-benzene has also been used for the latter purpose. ... 

Acid-catalyzed dealkoxylation is particularly suitable for the preparation of highly reactive, cationic iron(IV) carbene complexes, which can be used for the cyclopropanation of alkenes [438] (Figure 3.11). Several reagents can be used to catalyze alkoxide abstraction these include tetrafluoroboric acid [457-459], trifluoroacetic acid [443,460], gaseous hydrogen chloride [452,461], trityl salts [434], or trimethylsilyl triflate [24,104,434,441,442,460], In the case of oxidizing acids (e.g. trityl salts) hydride abstraction can compete efficiently with alkoxide abstraction and lead to the formation of alkoxycarbene complexes [178,462] (see Section 2.1.7). 

The same approach allows preparation of various pyrylium carboranes from the corresponding 4/f-pyran carboranes 174a,b and 175b by the action of acetyl perchlorate,245 perchloric acid,244 and triarylamine radical cation salts,244,245 as well as electrochemically.243 The oxidation of condensed 4H-pyran 345 with trityl perchlorate, 2,3,5,6-tetra-substituted 4f/-pyrans 431 and 153 with tropylium tetrafluoroborate or 153 with heterocyclic salt 393 led to useful preparations of pyrylium salts 394,330 395a,359 and 395b,360 respectively. 

Di-te/Y-butyl-4//-thiopyran (363) as well as its 4-methyl derivative 243 were readily aromatized to thiopyrylium salts 403 using trityl tetra-fluoroborate.286 2,4,6-Triphenyl-4//-thiopyran (45) (R = Ph) was analogously converted to salts 404 by the action of methyl iodide, dimethyl sulfate, triethyloxonium tetrafluoroborate,39 perchloric acid,362 or oxygen in acetic acid.363... 

When nitronium tetrafluoroborate was attempted to react with the trityl cation in CH2CI2 or sulfolane, no nitration occurred due to the deactivating effects of the carbenium ion center in 215. Nitration of deactivated substrates is also readily accomplished by reaction with NO2CI with three mole excess AICI3 suggesting Lewis acidic electrophilic solvation of the nitronium cation (217, eq 62).105... 

Improved preparation. Trityl fluoroborate can be prepared conveniently by the reactions of triphenylmethyl chloride with anhydrous tetrafluoroboric acid-dimethyl ether complex in dry benzene ... 

Tetrafluoroboric acid treatment of 7-amino-3-trityl-3//-azepines (11) converts them into the azanorcaradiene salts (12) which revert back to (11) on treatment with potassium carbonate in acetone <88T3309>. Warming compounds (11) converts them into 2-amino-6-trityl-3//-azepines (13). 

Two new procedures have appeared for the regeneration of alcohols from their TBDMS ethers, using either NBS in aqueous DMSO (a cheap and easy alternative) or a tetrafluoroborate salt (lithium or trityl). The tri-isopropylsilyl (TIPS) group has been examined as a protecting function for hydroxy-groups. TIPS ethers are found to be intermediate in stability towards acid hydrolysis between TBDMS ethers and the more resistant t-butyldiphenylsilyl (TBDPS) ethers. Base hydrolysis is slower than in acid, and TBDPS ethers now react more rapidly than TIPS ethers. Not surprisingly the TIPS group may be removed by fluoride ion. 

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