Triflate aryl ester phenol

Triflates derived from phenols are carbonylated to form aromatic esters by using Pd-Ph3P. The carbonylation of triflates is 500 times faster if DPPP (XLIV) is used [219]. This reaction is a good preparative method of benzoates from phenols and naphthoates from naphthols [220]. Carbonylation of enol triflates derived from ketones and aldehydes affords a,/Cunsaturated esters. The enol triflate in 451 is more reactive than the aryl triflate and the carbonylation proceeds stepwise chemoselectively. At... 

Itami et al. observed that an aryl ester could replace an aryl halide in their azole arylation protocol such a finding led to the first method for Ar-H/Ar-0 couplings and dramatically increased its synthetic utility simply due to the availability of phenols. The Ni(cod)2/dcype catalyst system was active for the coupling of azoles 152 with phenol derivatives such as carbamates, carbonates, mesylates, triflates, and tosylates to afford 2-arylazole products 153A-D in high yields (Scheme 10.53). ... 

A reaction which is related to hydroxy-de-diazoniations is the formation of aryl trifluoromethylsulfonic esters (aryl triflates, ArOSC CFs) which became widely used reagents because of their leaving-group properties. The classical method of synthesis by esterification of phenols with trifluoromethane-sulfonic anhydride or -sulfonyl halide is, however, not applicable for the preparation of aryl triflates bearing a (free)... 

Reactions catalyzed by transition-metal complexes allow the synthesis of a variety of esters ruthenium(II) promotes the addition of acids to alkynes,379 380 e.g. 2,6-difluorobenzoic acid (9) undergoes addition to but-l-en-3-yne to furnish the enol ester 10.380 Aryl bromides381 and aryl or vinyl triflates,382-384 but also aryl chlorides when their tricarbonylchromium(O) complexes are used,385 react with palladium382- 385 or cobalt complexes38 to form a C —M bond. Insertion of carbon monoxide into the carbon-metal bond followed by trapping with an alcohol or phenol leads to ester formation, e.g. triflate 11 gives ester 12.382... 

Palladium-catalyzed carbonylation of aryl triflates in the presence of an alcohol141 or amine1423 provides a good method for preparation of arenecarboxylic esters and amides from phenols (equation 121). However, palladium-catalyzed cyanation of 5,6,7,8-tetrahydro-2-naphthyl triflate with potassium cyanide failed completely whereas the more reactive tetrakis(triphenylphosphine)nickel(0) could catalyze the same reaction which gives the nitrile in a good yield142b (equation 122). 

In none of our extensive test reactions of aryl halides with benzoic acids carried out in the presence of diverse palladium catalysts, we were able to detect even traces of the unsymmetrical biaryl. Instead, we observed mostly homocoupling and dehalogenation products in some cases along with phenol esters. The conversion of aryl triflates with potassium benzoates did not lead to the desired biaryls, either, but to the phenol esters instead. 

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