Superacidic Activation of α,β‐Unsaturated Amides and Their Electrophilic Reactions

Abstract

The electrophilic reactivity of α,β‐unsaturated amides towards weak nucleophiles such as arenes and cyclohexane, initiated either with triflic acid (CF3SO3H) or with excess AlCl3, has been studied. The amides generally condense readily with aromatics in the presence of AlCl3 to give 3‐arylpropionamides and related compounds in excellent yields, while some amides also undergo selective ionic hydrogenation with cyclohexane to give saturated amides. The proposed mechanism of these reactions involves dicationic intermediates (superelectrophiles). The direct observation of a dicationic species (by low‐temperature NMR) is reported. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

A synthesis of 4-aryl quinolin-2(1H)-ones by acidic zeolite promoted intramolecular cyclization of N-aryl amides of 3-arylpropynoic acids

“…17 Zeolite CBV-720 was observed to be quite tolerant to substituents on both aromatic rings of the amides 1a-r. This was in contrast to a previous report where the Brønsted acid CF 3 amides bearing electron-withdrawing groups on the N-aryl ring were used. 17 Surprisingly, amides 1c and 1g, possessing methyl groups in meta positions on the N-aryl moiety, were largely unreactive (entries 4, 5 and 9).…”

Supported phosphotungstic acid catalyst on modified activated carbon for Friedel–Crafts alkenylation of diverse aromatics to their corresponding α-arylstyrenes

“…Moreover, the low catalytic efficiency could be observed while the HY was used as catalyst for the alkenylation, ascribed to the reaction only taking place on the external surface of the catalyst because of its narrow pore channels within the HY zeolite, as well as the improvement in the catalytic efficieny and enlargehttp://dx.doi.org/10.1016/j.apcata.2015.07.007 0926-860X/© 2015 Elsevier B.V. All rights reserved. ment in scope of substrates are deirable [11,13]. Recently, it was demonstrated that the Fe-containing mesoporous alluminosilicate exhibited vey high activity for the Friedel-Crafts alkenylation of phenols with aryl-substituted alkynes under mild conditions [14].…”

Reactions of arylacetylenic compounds with arenes in the presence of aluminum halides

“…Various Lewis acids have also found wide application in the chemistry of alkynes [12]. However, until recently the use of such common Lewis acids as aluminum halides AlBr 3 and AlCl 3 for direct activation of triple carbon-carbon bond was fairly limited and occasional [13][14][15]. Effective participation of aluminum halides in electrophilic activation of acetylenic compounds was demonstrated by us only recently [16][17][18].…”