P-Methoxybenzyl thioethers

S-p-Methoxybenzyl Thioether RSCH2C6H4-/ -OCH3 (Chart 7) Formation... 

The S-p-methoxybenzyl thioether of cysteine has also been utilized in a synthesis of oxytocin (Table 7.1). In these studies [15, 17] the thioether was removed with refluxing trifluoroacetic acid in the presence of anisole. The ability of trifluoroacetic acid to cleave the S-/>-methexybenzyl group (albeit at reflux) is probably a reflection of the increased stability of the cation as compared to the benzyl carbonium ion. The activity of the oxytocin obtained by this route (after air oxidation of... 

An effective and mild electrocatalytic procedure for the deprotection of the 1,3-dithiane group of (68), giving the ketone (67), has been developed by using a small amount of tris(p-tolyl)amine as a homogeneous electron-transfer catalyst (Scheme 26) [86]. The scope and limitations are discussed in detail [87]. The method can be applied also for oxidative removal of the 4-methoxybenzyl thioether protecting group from poly-cystinyl peptides [88]. 

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