Arenecarboxylic acid arenecarboxylate ester

Carboxamides and esters of arenecarboxylic acids are obtainable directly by reacting arenediazosulfones (Ar — N2 —S02 —Ar ) with CO and amines or alcohols, respectively, in the presence of Pd catalysts (Kamigata et al., 1989). Aromatic aldehydes are formed if the reaction is carried out in the presence of triethylsilane (Kikukawa et al., 1984). In an analogous way, arenediazonium salts can be transformed into ketones (ArCO —R R = CH3, C2H5, or C6H5) in the presence of stan-nanes, R4Sn (Kikukawa et al., 1982). 

These quinoxalinylalkyl esters of aUcane- or arenecarboxylic acids are sometimes used as intermediates (see, e.g.. Section 3.4.2). The formation of an analogous quinoxalinylmethyl nitrate is included in this section. Examples follow. 

The photochemical reactions of arenecarboxylic acid esters with alkenes has received recent attention by Cantrell. - For example, irradiation of 2,3-dimethyl-2-butene and methyl benzoate gave a mixture of alkoxyoxetane (56), carbonyl-alkene metathesis product (57) and ketone (58), resulting from alkoxy radical allylic hydrogen abstraction and radical recombination. Such alkoxyoxetane photoproducts are... 

Some of the latest developments in terms of substrates for the Heck reactions are nitrophenyl benzoates [55], acyl benzoates (mixed anhydrides) [236], and substituted benzoic acids [53]. For the last two, the leaving groups are carbon dioxide and carbon monoxide, respectively. A variety of alkenes have been coupled with these substrates. While esters and anhydrides presumably react in a catalytic cycle like that of the classical Heck reaction [237], arenecarboxylic acids, when treated with an equimolar amount of a silver salt as reoxidant, appear to undergo a nonclassical Heck reaction as demonstrated by the coupling with 2-cyclohexenone to give a 3-arylcyclohexenone. 

O-acetyl-jS-D-glycopyranosides from 0-, m- and p-02T C H 0 a-nitro esters from methyl nitroacetate, and alkyl phenyl selenides from PhSe". Similarly arenesulfonyl fluorides or isothiocyanates can be produced from arenesulfonyl chlorides and F" or SCN", and arene-carboxylic acid cyanides and isothiocyanates from arenecarboxylic acid chlorides and CN" or SCN ... 

Cantrell, T. S., Allen, A. C., and ZifFer, H., Photochemical 2-1-2 cycloaddition of arenecarboxylic acid esters to furans and 1,3-dienes 2-1-2 cycloreversion of oxetanes to dienol esters and ketones, /. Org. Chem., 54,140,1989. 

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