Thioethers vinylic hydrolysis

Sulfur ylides have been used to generate bicyclic macrolactams, as shown in Scheme 35. Argogel-bound thioacetic acid 130 was synthesized from thioacetic acid esters by alkylation with Argogel-Cl resin and subsequent basic hydrolysis of the ester (not shown in Scheme 35). Esterification with co-hydroxy vinyl ketone 131 gave intermediate 132. Alkylation with MeOTf activated the thioether and reaction of 133 with DBU in CH2CI2 at room temperature provided the macrocycle 134 containing an additional cyclopropyl unit in 52 % yield as the pure trans diastereoi-somer [51]. 

Hydrolysis of Vinylogous Thioacetals. Carbanions prepared by lithiation of y-phenylthioallyl phenyl thioethers can serve as synthetic equivalents of /3-acyl vinyl anions. Umpolung of the usual electrophilic reactivity of 2-cyclohexenone is achieved by a sequence exploiting electrophilic capture of a hthiated vinylogous thioacetal and subsequent CuOTf-assisted hydrolysis (eq 57). Otherwise unfunctionalized vinylogous thioacetals can be hydrolyzed to enones by mercury(II) chloride in wet acetonitrile. However, the keto-substituted derivative in eq 57 gave only a 25% yield of enone by this method. A superior yield was obtained by CuOTf-assisted hydrolysis. ... 

Isolated cytochrome c in neutral solution shows absorption bands at 408, 530, and 695 m/x in the oxidized form and at 415, 520, and 550 m/x in the reduced form. The heme group is not readily removed by treatment with acid acetone. Following hydrolysis with hydrochloric acid a porphyrin can be isolated which is referred to as porphyrin c. This porphyrin differs from protoporphyrin IX in the nature of side chains 2 and 4 in which the vinyl groups are replaced by thioether bridges with cysteine (Fig. 10). 

Electrophilic addition of bromodimethylsulphonium bromide to alkenes gives, after dehydrobromination, variable yields of vinylsulphonium salts. Hydrolysis of the vinyl thioether derivatives gives a formal conversion of an alkene into a carbonyl compound with some degree of control over regioselect-ivity. Halohydrins (derived from alkenes) can be converted into ketones by dehydrohalogenation with potassium carbonate, catalysed by palladous acetate. ... 

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