Tritylone alcohol

Tritylone alcohol reacts readily with alcohols to give tritylone ethers. Selective reaction of primary alcohols in the presence of secondary alcohols is possible. These new ethers are more stable to acid than trityl ethers. They can be cleaved by Wolff Kishner reduction. ... 

The suitability of tritylone ethers as protecting groups for alcohols has been explored, with cholesterol among model alcohols.The ether (134) was formed from tritylone alcohol and cholesterol under acidic conditions with azeotropic... 

The p-cyanobenzyl ether, prepared from an alcohol and the benzyl bromide in the presence of sodium, hydride (74% yield), can be cleaved by electrolytic reduction (—2.1 V, 71% yield). It is stable to electrolytic removal ( — 1.4 V) of a tritylone ether [i.e., 9-(9-phenyl-10-oxo)anthiyl ether]. ... 

The tritylone ether is used to protect primary hydroxyl groups in the presence of secondary hydroxyl groups. It is prepared by the reaction of an alcohol with 9-phenyl-9-hydroxyanthrone under acid catalysis (cat. TsOH, benzene, reflux, 55-95% yield).It can be cleaved under the harsh conditions of the WolfT-Kishner reduction (H2NNH2, NaOH, 200°, 88% yield), " and by electrolytic reduction (-1.4 V, LiBr, MeOH, 80-85% yield). It is stable to 10% HCl, 55 h. ... 

The tritylone group (22), which has been used199 for the protection of alcohols, resembles the trityl group, but it is more stable to acid. It... 

Tritylone ethers (57), used as acid-stable protecting groups for alcohols, are cleaved under Wolff-Kishner (Huang-Minlon) conditions as the unblocking step. ... 

Carbinols conjugated with aromatic systems, such as benzylic alcohols [59-62], trityl (VIII), tritylone (IX), and benzhydryl alcohols [59,62,63], and 9-hydroxy-9-phenylan-throne, heteroaromatic systems [64], a-hydroxy ketones [65-67], a-hydroxy acids, and their derivatives [68-70] can also be cleaved at potentials less negative than that of the activating group. Thus the radical anion of benzyl benzoate cleaves rapidly to benzoate and benzyl radical, which is reduced to the anion protonation leads to toluene. In the absence of added proton donor, the base generated during the reduction (EGB) may cleave the ester to benzoate and benzyl alcohol [44]. 

The formation of triphenylmethyl (trityl) ethers from trityl chloride and primary or secondary alcohols is another reaction now found to be catalysed by DMAP. In this procedure, as with the silylation reported above, stoicheiometric triethylamine is used to regenerate the DMAP. Tritylone ethers (60) are more... 

The utility of but-2-enyl ethers as alcohol protecting groups has been described the function is stable to mild acid and base, but is readily cleaved by potassium t-butoxide in DMSO at room temperature. A full description of the use of tritylone ethers as protecting groups has been published. 

An alcohol protecting group cleavable by specific base catalysis is offered as an alternative to the more common acid-labile functions. Tritylone ethers... 

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