Pyryliumverbindungen. 36. Substituierte Benzoesäureester aus 2,4,6-Triaryl-pyryliumsalzen und α-Ketocarbonsäureestern

Pyrylium Compounds. 36. Substituted Benzoic Acid Esters from 2,4,6-Triarylpyrylium Salts and α-Ketocarboxylic Acid Esters 2,4,6-Triarylpyrylium salts 1 react with α-ketocarboxylic acid esters 2 in the presence of two equivalents of an appropriate condensing agent (e.g. dialkylamine salts of weak acids, triethylamine/acetic acid, or sodium acetate) to give 2-aroyl-3,5-diarylbenzoic acid esters 3 . However, using only one equivalent of the condensing agent, the formation of 3,5-diarylbenzoic acid esters 5 predominates. Alkaline saponification of the new esters 3 and 5 yields the corresponding substituted benzoic acids 4 and 6 , respectively. – I.r., u.v., n.m.r. and mass spectroscopic data of the novel products 3 – 6 are reported.