Reactions of linear conjugated dienone structures with arenes under superelectrophilic activation conditions. An experimental and theoretical study of intermediate multicentered electrophilic species

Abstract

Reactions of linear conjugated dienone structures ArCH=CHCH=CHC(=O)X, 1,5-diarylpenta-2,4-dien-1-ones (X = Ar), 5-phenylpenta-2,4-dienoic acid (Ar = Ph, X = OH) and its methyl ester (Ar = Ph, X = OMe), with...

DFT insights into superelectrophilic activation of α,β-unsaturated nitriles and ketones in superacids

“…9,11,[30][31][32] It is not surprising, therefore, that these and analogous species have been repeatedly proposed as key superelectrophilic 2 intermediates in the corresponding reactions with weak nucleophiles, such as benzene, deactivated aromatics and alkanes. 6,[8][9][10][11][12][13][14][15][16][17][18][19][20][22][23][24][25][26]33 On the other hand, perhaps the most widely proposed candidate for the role of a strong electrophile derived from α,β-enones in superacids is the O,O-diprotonated form 6 (Fig. 4).…”

“…undergo a specific kind of electrophilic activation upon action with strong Brønsted or Lewis acids. 1–25 This allowed involving them in a large variety of Friedel–Crafts type transformations, offering quite appealing synthetic solutions. Fig.…”

“…9,11,30–32 It is not surprising, therefore, that these and analogous species have been repeatedly proposed as key superelectrophilic 2 intermediates in the corresponding reactions with weak nucleophiles, such as benzene, deactivated aromatics and alkanes. 6,8–20,22–26,33…”

5,5,5-Trichloropent-3-en-one as a Precursor of 1,3-Bi-centered Electrophile in Reactions with Arenes in Brønsted Superacid CF3SO3H. Synthesis of 3-Methyl-1-trichloromethylindenes

“…Based on our recent studies on superelectrophilic activation of electron deficient alkenes [ 19 , 20 , 21 ], we undertook this study on electrophilic activation of E -5,5,5-trichloropent-3-en-2-one 1 (CCl 3 -enone). The presence of two electron withdrawing groups, COMe and CCl 3 , at the carbon-carbon double bond increases its electrophilicity, especially under protonation of the carbonyl oxygen-resulting O -protonated species A ( Scheme 1 b).…”