Positional reactivity of dibenzofuran in electrophilic substitutions

Abstract

95; H, 7.31; N, 10.15.4-Amino-5-tert -butyl-rl'-(dimethylamino)bipheny1-3-carbonitrile (8c) was prepared from 0.17 g (0.49 mmol) of 13 in 25 mL of CH3CN by addition of 1 mL of HBF, (40% in ether).After being stirred for 45 min, the solution was treated with lu until an aqueous extract was no longer acidic. The solvent was evaporated, and the residue was several times extracted with ether. The resulting colorless material was recyrstallized from methanol and yielded 70 mg (51%) of 8c: mp 137-138 "C; MS m / z 293 (100, M' ), 278 (28), 263 (10); 'H NMR (90 MHz, CCl,) 6 1.44 (9, 9 H, tert-butyl), 2.95 (s,6 H, N(CH3),), 4.49 (s,2 H, NH,), 6.5-7.6 (m, 6 H, aromatic protons); l R (KBr) 347013390 (NH), 2900 (CH), 2205 (CN). Anal. Calcd for CIOHaN3: C, 77.78; H, 7.90; N, 14.32. Found: C, 77.61; H, 7.71; N, 14.02. Diethyl 2-[3,5-Di-tert-butyl-l-[4-(dimethylamino)-phenyl]-4-imino-2,5-cyclohexadien-1-yllmalonate ( 12). A 2.55-g (16-"01) portion of diethyl malonate was treated with 0.12 g (5.2 "01) of Na dissolved in 20 mL of EtOH. The resulting solution was added to a solution of 4c (from anodic oxidation of 0.28 g (0.86 mmol) of aniline IC) in acetonitrile. After immediate decolorization, the excess of diethylmalonate was evaporated at 100 "C (0.1 Torr). The product 12 was isolated as an oil (yield, 93%): MS m/z 482 (6, M+), 426 (13), 324 (loo), 309 (44), 173 (68); 'H NMR (90 MHz, CDC13), 6 1.13 (t, 6 H, J = 7 Hz, OCH,CH,), 1.31 (8, 18 H, tert-butyl), 2.89 ( 8 , 6 H, N(CH3),), 4.02 (4, J = 7 Hz, OCHzCH3), 4.17 (8, CH(CO0Et)z; the integration of the signals at 4.02 and 4.17 corresponds to 5 H), 6.68 (8, vinylic protons), 6.84 (q, A2Bz, J = 9 Hz, aromatic protons; the integration of the signals between 6.56 and 7.11 corresponds to 6 H), a signal for the NH proton was not found, in CeDe it was detected at 9.98 (9, broad, 1H); IR (KBr) 3400 (NH), 2960 (CH), 1760/1735 (C=O), 1565 (C=N) cm-'. Anal. Calcd for C29H42N204: C, 72.17; H, 8.77; N, 5.80. Found: C, 71.95; H, 8.61; N, 5.72. 1,5-Di-tert -butyl-3-[ 44 dimet hylamino) phenyl]-6-imino-2,4-cyclohexadiene-1-carbonitrile (13) was obtained after addition of a 7% excess of NBu4CN to the electrogenerated solution of 4c (from 0.27 g (0.83 mmol) of IC). It was recrystallized from petroleum ether (30/50), giving yellow crystals (yield, 64%): mp 98 "C dec; MS m / z 349 (1, M+), 324 (2), 293 (loo), 278 (36); 'H NMR (90 MHz, CC1$ 6 1.06 (8, 9 H, tert-butyl), 1.33 (8, 9 H, tert-butyl), 2.99 (9, 6 H, N(CH3),), 5.97 (d, 1 H, J = 2 Hz), 6.60 (d, J = 2 Hz, vinylic protons), 6.91 (9, A2B2, J = 9 Hz, aromatic protons, the integration of the signals between 6.50 and 7.50 corresponds to 5 H), 10.69 (9, broad, 1 H, NH); IR (KBr) 3390 (NH), 2890 (CH), 2225 (CN), 1585/1525 (C=N) cm-' . Anal. Calcd for C23H31N3: C, 79.04; H, 8.94; N, 12.02. Found: C, 79.25; H, 9.12; N, 12.23.Reaction of 4c with Thiophenolate Ion. To a solution of cation 4c (derived from 0.28 g (0.86 mmol) of IC) in acetonitrile were added 1 g of powdered NazCOs and 1 g (9.0 mmol) of thiophenol. From the resulting colorless solution ...

Aromatic reactivity revealed: beyond resonance theory and frontier orbitals

“…6a, S10 and S15 †). 52 Borazarophenanthrenes have been shown to pose a particular challenge to many reactivity models, with FMO theory, the condensed Fukui function and atomic charge calculations all failing to predict the observed reactivity patterns (Fig. S15 †).…”

Synthesis and characterization of cell-permeant 6-nitrodibenzofuranyl-caged IP3

“…1, which is known to have a distinct reactivity for acylation/bromination and nitration. 27 The former occurs at the 2-position, whereas the latter occurs at the 3-position. Initially, we coupled the known 17 secondary bromide 3 to diol 4 to give alcohol 5 with high regioselectivity but low yield (5%).…”

Synthesis of multi‐substituted dibenzo[b,d]furan

“…Such reactions provide, either mono substituted [5] or multi-substituted dibenzo [b,d]furans [6]. However the disadvantage of such reactions is that we tend to get substitutions at undesired position on the heterocycle.…”

“…A literature survey revealed that most of the substituted dibenzo [b,d]furans have been synthesized by electrophilic substitution of commercially available dibenzo [b,d]furan. Such reactions provide, either mono substituted [5] or multi-substituted dibenzo[b,d]furans [6]. However the disadvantage of such reactions is that we tend to get substitutions at undesired position on the heterocycle.…”