Carboxylic anhydrides Pummerer rearrangement

Electrc hilic reagents capable of Mnging about Pummerer rearrangement include inoiganic and organic acids, carboxylic anhydrides, acyl halides, isocyanates, caibodiimides, irimethylsilyl halides and triflate, sulfonyl and sulfenyl halides, phosphorus pentoxide and many typical Lewis acids such as boron... 

Unlike the synthesis of phenols from non-aromatic sources that of thiophenol by similar methodology is virtually unknown. The synthesis shown of the diacetate of a tricyclic compound containing an o-substituted thiophenol system would appear to be applicable to the simpler central portion and to bicydic analogues. Ethyl 4-(1-benzyl-2-thioxo-pyrrolidin-3-yl)-5-(diazoacetyl)-pyrrole -2-carboxylate in dichloromethane was treated with boron trifluoride etherate in the same solvent and after 15 mins, the intermediate shown resulted which in a sealed tube (under vacuum) with acetic acid/acetic anhydride (3 1) at 132°C during 90mins. produced by a Pummerer rearrangement, ethyl... 

Pummerer Rearrangement. 5 Ethyl ethanethlosulfinate on treatment with trifluoroacetic anhydride produces an approximately equimolar mixture of the corresponding disulfide and sulfinyl trifluoroacetates. The reaction proceeds with the initial acylation of the sulfinyl oxygen followed by formation of the sulfenyl trifluoroacetate as transient intermediate (eq 7). This sulfinyl carboxylate is only stable in solution at room temperature, as attempted isolation was unsuccessful and led to the isolation of the sulfonate and the disulfide. ... 

---