Synthesis of Annularly Functionalized Dicationic Benzimidazolophanes and Benzotriazolophanes

Abstract

Annularly functionalized dicationic benzimidazolophanes (1, 2, and 3) and benzotriazolophanes (1a, 2a, and 3a) were synthesized by alkylation followed by double quaternization.Cationic heterophanes [1] are rapidly developing classes of cyclophanes, which mimic molecular recognition events in biological systems by apolar complexation of guest molecules in aqueous solution. Some of the important application aspects of cationic heterophanes are their ability to show increased chelating effects, solubilizing power,

Active Cobalt Catalyst for the Cleavage of Benzyl Ether

“…Chemical shifts (in ppm) were referenced with tetramethylsilane (δ = 0 ppm) in deuterated chloroform, deuterated acetone, or deuterated benzene. 13 C NMR spectra were obtained by using the same NMR spectrometers and were calibrated with CDCl 3 (δ = 77.00 ppm), (CD 3 ) 2 CO (δ = 29.84, 206.26 ppm), or C 6 D 6 (δ = 128.00 ppm). High-resolution mass spectrometry was performed on a mass spectrometer.…”

“…(Dodecyloxy)(ethyl)dimethylsilane (1b): colorless oil; 1 H NMR (400 MHz, CDCl 3 ) δ 3.50 (t, 2H, J = 6.7 Hz), 1.40−1.50 (m, 2H), 1.15−1.28 (m, 18H), 0.88 (t, 3H, J = 7.9 Hz), 0.81 (t, 3H, J = 6.8 Hz), 0.50 (q, 2H, J = 7.9 Hz), 0.01 (s, 6H); 13 (Dodecyloxy)triethylsilane (1e): colorless oil; 1 H NMR (400 MHz, (CD 3 ) 2 CO) δ 3.50 (t, 2H, J = 6.4 Hz), 1.38 (m, 2H), 1.30−1.10 (m, 18H), 0.83 (t, 9H, J = 7.9 Hz), 0.75 (t, 3H, J = 7.0 Hz), 0.47 (q, 6H, J = 7.9 Hz); 13…”

“…1 A plethora of reagents and methods have been used to remove benzyl ethers, including catalytic hydrogenolysis, 2−6 reductive cleavage (lithium naphthalenide 7,8 and TIBAL, 9 etc. 10,11 ), Lewis acid (TMSI 12 and TiCl 4 , 13 etc. 14−16 ), or oxidation-based cleavage (2,3-dichloro-5,6-dicyano-1,4-benzoquinone 17,18 and 4-acetamido-2,2,6,6-tetramethylpiperidine-1oxoammonium tetrafluoroborate 19 ).…”

“…(Benzyloxy)butyl pivalate (4a): colorless oil; 1 H NMR (400 MHz, CDCl 3 ) δ 7.17−7.31 (m, 5H), 4.44 (s, 2H), 4.00 (t, 2H, J = 6.3 Hz), 3.43 (t, 2H, J = 6.2 Hz), 1.64 (m, 4H), 1.12 (s, 9H);13 C NMR (100 MHz, CDCl 3 ) δ 178.6, 138.5, 128.4, 127.6, 127.6, 72.9, 69.8, 64.2, 38.7, 27.2, 26.3, 25.5; HRMS (ESI) calcd for C 16 H 24 O 3 [M + Na] + 287.1623, found 287.1615. 4-((Dimethyl(phenyl)silyl)oxy)butyl pivalate (4b): colorless oil; 1 H NMR (400 MHz, CDCl 3 ) δ 7.46−7.52 (m, 2H), 7.26−7.34 (m, 3H), 3.96 (t, 2H, J = 6.3 Hz), 3.54 (t, 2H, J = 6.2 Hz), 1.46−1.65 (m, 4H), 1.11 (s, 9H), 0.30 (s, 6H); 13 C NMR (100 MHz, CDCl 3 ) δ 178.5, 137.9, 133.4, 129.6, 127.8, 64.1, 62.5, 38.7, 29.1, 27.2, 25.2, −1.8; HRMS (ESI) calcd for C 17 H 28 O 3 Si [M + Na] + 331.1705, found 331.1702.…”

Azolium Cyclophanes

“…For example, Baker et al found that in the preparation of the p -xylyl linked imidazolium cyclophanes 27-29, as the number of methyl groups on the xylyl component of the bis-azole was increased (none in 27, two in 28 and four in 29) the requirement for the use of low concentrations to avoid polymeric products decreased (Fig. 118 69% [18] n 126 n = 1 54% [16] 127 n = 2 40% [16] 128 X = CH, R = H 70% [47,48] 129 X = CH, R = Br 60% [47,48] 130 X = CH, R = CO 2 H 50% [47,48] 131 X = CH, R = CO2Me 45% [47,48] 132 X = CMe, R = H 50% [47,48] 133 X = CMe, R = Br 55% [47,48] 134 X = N, R = H 60% [34,48] 135 X = N, R = Br 57% [34,48] 136 X = N, R = CO 2 H 40% [34,48] 137 X = N, R = CO 2 Me 43% [34,48] 120 X = CH 52% [46] 121 X = N 45% [46] 122 m X = CH 48% [46] 123 m X = N 55% [46] 124 p X = CH 54% [46] 125 p X = N 54% [46] m or p m or p Fig. This result may be a consequence of the additional methyl groups restricting conformational freedom of the imidazole unit in the intermediate formed during the 3+1 synthesis, and thereby favouring cyclization over polymerization [26].…”