Aryl carbamates, hydroxylation

The C-H hydroxylation of para-, meta- and more sterically hindered < rt/j< -substituted aryl carbamates in DCE is catalysed by [RuCl2(p-cymene)]2 (61) using Phl(TFA)2 as the oxidant at a low temperature with excellent chemo- and site-selectivities. ... 

Modification of C6-OH of the aglycone is not only possible, it is preferable. Methylation I of this hydroxyl group yields an antibiotic (cla-I rithromycin) with superior pharmacokinetics I (82). Numerous 6-0-aryl derivatives yielded I agents with superior antibiotic activity for I erythromycin, ketolide, and 11,12-carbamate derivatives (106, 116). The authors of this I study speculated that the newly introduced... 

Starch reacts with isocyanates to produce carbamates (urethanes), which are esters of carbamic acid. Several reactions of starch with phenyl-, various aryl-, 1-naphthyl-isocyanates or 1,6-hexamethylene- and 2,4-tolyl-diisocyanates were conducted either in pyridine or morpholine below the boiling point of these solvents.2546-2548 In each case all three hydroxyl groups of the glucose units reacted to give tricarbanilates, provided a sufficient amount of the isocyanate reagent was used. 

Formal replacement of an aromatic hydroxyl group by a thiol group is shown in the preparation of thiophenols by way of O-aryl iV,A-dialkylthio-carbamates, which undergo rearrangement to. the S-esters, whence hydrolysis gives the thiophenols.373 The same reaction occurs in the heterocyclic series. Good yields are obtained in all the steps. 

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