0-Triphenylmethyl derivatives hydrolysis

As with triphenylmethyl salts, the hexachlorantimonate derivative of tropylium ion is by far the most convenient to handle and to use as a catalyst. In this case, thermal decomposition or hydrolysis of the tropylium salt is almost nonexistent under ordinary conditions, and the catalyst can be prepared conveniently, purified, and stored over long... 

Some imidoyllithiums 52 derived from triphenylmethyl isocyanide (51) dissociate to produce nitriles, which react with an organolithium reagent to give the corresponding imines and, after their hydrolysis, ketones. The intermediate nitrile can be isolated working at —78°C, whereas for the isolation of imines or ketones, after addition of the organolithium, the reaction was allowed to warm to room temperature (Scheme 14)74. The structure of the imidoyllithium intermediate has been assigned by IR spectroscopy... 

Derivation of polymer also serves as a useful method for tacticity determination. Poly(triphenylmethyl methacrylate) is easily converted to PMMA by hydrolysis and the subsequent methylation with diazomethene. The polymers obtained by anionic polymerization not only in toluene but also in tetrahydrofuran are highly isotactic.189 Even the radical polymerization of the monomer gives an isotactic polymer. 

Pyrylium phosphonic acids (60a) have been prepared by the reaction of triethyl phosphite with pyrylium salts followed by oxidation of the product (either before or after hydrolysis) with the triphenylmethyl carbonium ion. This approach has been used to obtain the analogous thiopyrylium phos-phonates (60b) and the cyclopropene and tropylidene derivatives (61) and (62). The enamine phosphonates (63) are readily accessible from addition... 

Ort/io-substituted benzaldehyde complexes have been prepared in high enantiomeric purity (97% ee), and in a one-pot sequence, from an optically pure hydrazone derivative, readily available from -q -benzaldehyde chromium tricarbonyl and SAMP [(S)-l-amino-2-(methoxymethyl)pyrrolidine]. The novelty derives from the combined use of a diastereoselective orthoaddition reaction of an organolithium nucleophile and a hydride abstraction with a triphenylmethyl cation. The subsequent acid hydrolysis serves to remove the hydrazone group, thus liberating the aldehyde functionality (Scheme 6.13). 

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