Carcinogenic nitrogen compounds. Part LXIV. The Ullmann–Fetvadjian reaction with anthrylamines

Intramolecular Reversible Addition Reactions to the C=O Group

“…The carboxylate anion of these acids always has an open structure (Ie) which does not depend on the structure of the acid molecule and on the substituent R [5,[7][8][9][10][11][12][13][14][15][16][17][18]. Since the acidity of the cyclic form (IB) is considerably lower than that of the open form (IA) [19] the cyclic anion (ID) does not appear in the equilibrium mixture in any detectable concentration.…”

“…The signals of protons located at the carbon atoms in the chain between ketone and carboxyl groups are only rarely used [27,43]. The signals of aldehyde and methine protons of aldehydrocarboxylic acids (HC=O in (IA) and HC(OH)O in (18») are also suitable for analytical measurements [11,12,14,[16][17][18]21,30].…”

“…2-Formylbenzoic acid in the solid state exists as the cyclic hydroxyphthalide (lOB, R = H) [62][63][64], and this form also predominates in the solutions (see Table 3) [5,8,12,26,65]. The same behavior applies to solutions of 2-formyl-5,6-dimethoxybenzoic (opianic) acid [16,18], but for 2-formyl-3-hydroxy-2-methylpyridine-4-carboxylic acid the equilibrium is shifted toward the open form [14,18].…”

“…The cyclization is accompanied by 1,4-dehydration to the lactone (17) [88-90]: o (17) o Z-3-Acylacrylic Acids (le). Z-3-Formylacrylic acid [2,35,91,92], its 2-methyl [93], 3-methyl [94], 2,3-halogeno [11,17,[95][96][97][98], and other 2,3substituted derivatives [99], and also Z-3-acetylacrylic acids [15,20,[100][101][102][103], exist in the solid state, as well as in solution, entirely in the ring form (18B) as does penicillic (Z-3-methacryl-3-methoxyacrylic) acid [104,105].…”

“…A dilution of solutions [10,30], a use of pyridine or triethylamine as solvent or their addition to solutions [30] shifts the equilibrium toward the open form. In acid media the equilibrium is shifted in favor of the less acid cyclic form [10,[16][17][18]. Raising the temperature favors the open form [65,131].…”