Triphenylmethyl chloride, amine alkylations

Amines can also be protected from unwanted acylation or from twofold alkylation by alkylation with a sterically demanding group that is amenable to selective removal after completion of the synthesis. The most commonly used groups for this purpose are triphenylmethyl derivatives. Amines are readily tritylated using trityl chloride in the presence of a tertiary amine. Deprotection is achieved by treatment with dilute... 

In Schemes 8.204 and 8,205 above we showed that tritylamines can be generated by reductive amination and N-alkylation of trityiamine. However, N-alkyla-tion of amines by triphenylmethyl chloride (mp 110-112 °C) or triphenylmethyl bromide (mp 152-154 °C) in an aprotic solvent such as chloroform or chloro-form-DMF mixtures together with a base such as triethylamine is the most common method for introduting the trityl group [Scheme 8,212]434 4,4 -Dimethoxy-trityl tetrafluoroborate and 4i4, 4"-trimethoxytrityl tetrafluoroborate are also... 

There is direct evidence, from ir and nmr spectra, that the fert-butyl cation is quantitatively formed when ferf-butyl chloride reacts with AICI3 in anhydrous liquid HCl. In the case of alkenes, Markovnikov s rule (p. 1019) is followed. Carbocation formation is particularly easy from some reagents, because of the stability of the cations. Triphenylmethyl chloride and 1-chloroadamantane alkylate activated aromatic rings (e.g., phenols, amines) with no catalyst or solvent. Ions as stable as this are less reactive than other carbocations and often attack only active substrates. The tropylium ion, for example, alkylates anisole, but not benzene. It was noted on p. 476 that relatively stable vinylic cations can be generated from certain vinylic compounds. These have been used to introduce vinylic groups into aryl substrates. Lewis acids, such as BF3 or AIEta, can also be used to alkylation of aromatic rings with alkene units. 

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