Trapping triphenylmethyl

Thiopyran-3(6//)-ones (133 R=H or Me) are converted into 3-hydroxythiopyrylium perchlorates (134 R = H or Me) by triphenylmethyl perchlorate. Deprotonation of these salts (134) by tertiary base did not liberate the thiopyrylium-3-olates (132) but instead gave dimeric products (135 and 136) in high yield. Evidence for the transient formation of the mesomeric betaines (132) is provided by the appearance of a greenish-yellow coloration which rapidly fades. The parent betaine (132 R = H) gave exclusively the endo dimer (136 R = H) (70%). In addition to the endo dimer (136 R = Me) (75%), the 5-methyl derivative (132 R = Me) also gave a small amount of the exo dimer (135 R = Me) (6%). The dimerization (132 136) appears to be rapid and irreversible Attempts to trap the... 

The introduction and cleavage of the trityl ether proceeds through a very well-stabilised triphenylmethyl carbocation. In the case of trityl ether bond formation, the reaction is performed under anhydrous conditions and the carbocation, which is formed by an SN1 mechanism, reacts with an alcohol. In the case of cleavage, the triphenylmethyl carbocation ion is formed by treatment with acid, which is then trapped by water or a nucleophilic solvent to give trityl alcohol or other derivatives, respectively. Trityl ethers have also been used to protect thiols. 

Hydride abstraction from tertiary amines by arylmethyl cations leads to iminium ions which can be hydrolyzed or trapped with nucleophiles. For example, r-butyldimethylamine reacts with triphenylmethyl perchlorate to give a 93% yield of the iminium salt. This can be trapped with acetophenone to give Ae Mannich product (Scheme 1). 

Ot.su and I azaki have reported on the use of triphenylmethylazobenzene (39) as an initiator. In this case, phenyl radical initiates polymerization and the triphenylmethyl radical reacts mainly by primary radical termination to form a macroinitiator. The early report that triphenylmethyl radical does not initiate MMA polymerization may only indicate a very low rate of polymerization. The addition of triphenylmethyl radical to MMA has been demonstrated in radical trapping experiments. ... 

N-CIDNP investigations of the decomposition of several unsymmetric diazenes and radical trapping experiments both confirm a mechanism involving initial cleavage of one carbon-nitrogen bond (P 7). In the case of phenylazotriphenylmethane, for example this cleavage leads to the phenyldiazenyl-triphenylmethyl radical pair... 

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