Trichloroisocyanuric Acid Mediated High-Yielding Synthesis of N-Acylbenzotriazoles under Mild Reaction Conditions

Abstract

N-Acylbenzotriazoles are achieved in good yields from the corresponding carboxylic acids by using only 0.35 equivalent of trichloroisocyanuric acid and 1.2 equivalents of PPh3. The salient features of the developed reaction path include an economic, facile, base-free, and equally useful method in milligram to gram scale.

Ultrasound-Assisted Synthesis of N-Acylcyanamides and N-Acyl-Substituted Imidazolones from Carboxylic Acids by Using Trichloroisocyanuric Acid/Triphenylphosphine

“…This signal completely disappeared after the addition of TCCA, giving rise to a new major peak at  p = 64.62 ppm corresponding to triphenylphosphonium chloride. 19,26 Other lower intensity signals were also observed at  p = 59.62, 23.94, and 23.66 ppm that could be attributed to other oxyphosphonium species 27 (see Figure S1 in the Supporting Information). These signals disappeared upon treatment with benzoic acid, when a single peak at  p = 29.23 ppm corresponding to triphenylphosphine oxide appeared.…”

“…As illustrated in Scheme 1, the applications of TCCA in combination with triphenylphosphine (PPh 3 ) as a carboxylic acid activator have recently been demonstrated in the synthesis of various derivatives. [18][19][20][21] Nonetheless, to the best of our knowledge, the reagent system has never been used in the synthesis of N-acylcyanamides or under ultrasonication.…”

Synform Issue 2019/10

“…Their synthetic strategy begins with the N-acylbenzotriazoles 1, prepared from the corresponding carboxylic acids by reaction with thionyl chloride, NBS/PPh 3 or PySSPy/PPh 3 and 1H-benzotriazole in dichloromethane. 6 "Although the reaction of N-acylbenzotriazoles with NaN 3 afforded the corresponding carbamates, thiocarbamates, and symmetric ureas in average to good yields via Curtius rearrangement, 5 the method was not equally applicable for the production of unsymmetrical ureas, which therefore became our next objective, 7 " explained Dr. Tiwari. A number of reactions with a diverse range of reagents were attempted, ending with the conclusion that N-acylbenzotriazole 1a (1.0 equiv) on treatment with aniline (1.0 equiv), TMSN 3 (1.0 equiv) and triethylamine (1.0 equiv) in anhydrous toluene at 110 °C afforded the required unsymmetrical urea derivative 2a in 83% yield.…”

Trichloroacetimidate-Triggered Expeditious and Novel Synthesis of N-Acylbenzotriazoles

“…Moreover, the carbonyl activation pathway has been explored, mainly because this process avoids the use of strong acids and bases which makes the transformation more convenient and practical. We have recently reported a new approach using 2,2 ' -dipyridyl disulfide/PPh3 26 and further extended this with the aid of TCICA/PPh3 27 for easy access to diverse N-acylbenzotriazoles from corresponding acids through a carbonyl activation pathway in high-to-excellent yields. In the context of carbonyl activation, a report is well documented for the conversion of carboxylic acids into respective amides (via acid chloride formation) using the combination of the activators trichloroacetonitrile (TCA) and PPh3.…”

“…27,40 White solid, yield: 0.230g (70%); m.p.=134-137 o C Rf = 0.5 (10% ethyl acetate/n-hexane);1 H NMR (500 MHz, CDCl3): δ= 8.38 (d, J = 9.0 Hz, 1H), 8.22-8.17 (m, 3H), 7.73-7.70 (m, 1H), 7.57-7.55 (m, 3H);13 C NMR (125 MHz, CDCl3): δ= 165.5, 145.7, 140.4, 133.1, 132.2, 130.5, 129.7, 128.8, 126.4, 120.2, and 114.7 ppm. (1H-benzo[d][1,2,3]triazol-1-yl)(2chlorophenyl)methanone(2b).…”