General procedures for synthesis of the condensation products.
Method A: A mixture of 5-arylfuran-2-carboxaldehyde 1a-h (2 mmol), benzothiazolium salt 4a,b (2.4 mmol) and a catalytic amount of potassium acetate (0.2 mmol) in dry acetonitrile (10-15 mL) was refluxed with stirring 1-5 h (monitored by TLC using 4:1 chloroform-methanol). After cooling down to room temperature the solid product was separated by filtration, washed with acetonitrile and methanol, dried and purified by crystallisation. Products 5a-6h were prepared using this method.
Method B: A mixture of 5-arylfuran-2-carboxaldehyde 1a-h (2 mmol) or furo[b]type aldehyde 2 or 3 (2 mmol) and benzothiazolium salt 3a,c (2.4 mmol) in methanol (15 mL) was refluxed for 1-4 h in the presence of a catalytic amount of pyridine (15 mg). Reactions were monitored by TLC (4:1 chloroform-methanol). After cooling down to room temperature the solid product was separated by filtration, washed with methanol and dried. Products 7a-9 were prepared by this procedure.
2-{(E)-2-[5-(4-Chlorophenyl)furan-2-yl]vinyl}-3-methyl-1,3-benzothiazolium iodide (5a). Reaction time: 85 min; yield 57%; m.p. 249-254°C (methanol); Calc. for C20H15ClINOS (479.76): 50.07% C, 3.15% H, 7.39% Cl, 2.92% N, 6.68% S; found: 50.22% C, 3.12% H, 7.43% Cl, 2.89% N, 6.71% S; UV: 463 (3.32); 1H-NMR (400 MHz): 8.42 (d, 1H, J(4,5) = 8.1 Hz, H-4), 8.24 (d, 1H, J(6,7) = 8.4 Hz, H-7), 8.08 (d, 2H, J(2´´,3´´) = 8.5 Hz, H-2´´, H-6´´), 8.12 (d, 1H, J(α,β) = 15.6 Hz, H-β), 7.87 (t, 1H, J(4,5) = 8.1 Hz, J(5,6) = 8.3 Hz, H-6), 7.78 (t, 1H, J(5,6) = 8.3 Hz, J(6.7) = 8.4 Hz, H-5), 7.74 (d, 1H, J(α,β) = 15.6 Hz, H-α), 7.61 (d, 2H, J(2´´,3´´) = 8.5 Hz, H-3´´, H-5´´), 7.47 (d, 1H, J(3´,4´) = 3.7 Hz, H-3´), 7.43 (d, 1H, J(3´,4´ ) = 3.7 Hz, H-4´), 4.36 (s, 3H, N+CH3); 13C-NMR (100 MHz): 170.9 (C-2), 157.0 (C-5´), 150.5 (C-2´), 142.1 (C-3a), 134.1 (C-4´´), 133.1 (C-β), 129.3 (C-6), 129.2 (C-2´´), 128.2 (C-5), 127.6 (C-7a), 127.5 (C-1´´), 126.7 (C-3´´), 124.2 (C-7), 123.7 (C-3´), 116.7 (C-4), 111.1 (C-4´), 110.1 (C-α), 36.2 (N+CH3).
2-{(E)-2-[5-(4-Bromophenyl)furan-2-yl]vinyl}-3-methyl-1,3-benzothiazolium iodide (5b). Reaction time: 160 min; yield 57%; m.p. 255-258°C (ethanol); Calc. for C20H15BrINOS (524.21): 45.82% C, 2.88% H, 15.24% Br, 2.67% N, 6.12% S; found: 46.05% C, 2.92% H, 15.19% Br, 2.62% N, 6.17% S; UV: 463 (3.69); 1H-NMR (400 MHz): 8.42 (d, 1H, J(4,5) = 8.0 Hz, H-4), 8.24 (d, 1H, J(6,7) = 8.4 Hz, H-7), 8.00 (d, 2H, J(2´´,3´´) = 8.4 Hz, H-2´´, H-6´´), 8.11 (d, 1H, J(α,β) = 15.2 Hz, H-β), 7.87 (t, 1H, J(5,6) = 7.8 Hz, J(6,7) = 8.4 Hz, H-6), 7.78 (t, 1H, J(4,5) = 8.0 Hz, J(5,6) = 8.3 Hz, H-5), 7.73 (d, 1H, J(α,β) = 15.2 Hz, H-α), 7.73 (d, 2H, J(2´´,3´´) = 8.4 Hz, H-3´´, H-5´´), 7.47 (d, 1H, J(3´,4´) = 3.7 Hz, H-3´), 7.43 (d, 1H, J(3´,4´) = 3.7 Hz, H-4´), 4.37 (s, 3H, N+CH3); 13C-NMR (100 MHz): 170.9 (C-2), 157.1 (C-5´), 150.5 (C-2´), 142.0 (C-3a), 132.1 (C-2´´), 133.1 (C-β), 129.3 (C-6), 128.2 (C-5), 127.8 (C-4´´), 127.6 (C-7a), 126.8 (C-3´´), 124.2 (C-7), 122.9 (C-1´´), 123.7 (C-3´), 116.6 (C-4), 111.1 (C-4´), 110.1 (C-α), 36.3 (N+CH3).
3-Methyl-2-{(E)-2-[5-(4-nitrophenyl)furan-2-yl]vinyl}-1,3-benzothiazolium iodide (5c). Reaction time: 270 min; yield 84%; m.p. 242-246°C (ethanol); Calc. for C20H15IN2O3S (490.32): 48.99% C, 3.08% H, 5.71% N, 6.54% S; found: 49.38% C, 3.14% H, 5.91% N, 6.61% S; UV: 453 (3.64); 1H-NMR (400 MHz): 8.44 (d, 1H, J(4,5) = 8.0 Hz, H-4), 8.37 (d, 2H, J(2´´,3´´) = 8.0 Hz, H-3´´, H-5´´), 8.30 (d, 2H, J(2´´,3´´) = 8.0 Hz, H-2´´, H-6´´), 8.27 (d, 1H, J(6,7) = 8.7 Hz, H-7), 8.16 (d, 1H, J(α,β) = 15.6 Hz, H-β), 7.89 (t, 1H, J(4,5) = 8.0 Hz, J(5,6) = 7.7 Hz, H-6), 7.85 (d, 1H, J(α,β) = 15.6 Hz, H-α), 7.80 (t, 1H, J(5,6) = 7.7 Hz, J(6,7) = 8.7 Hz, H-5), 7.66 (d, 1H, J(3´,4´) = 3.7 Hz, H-3´), 7.52 (d, 1H, J(3´,4´) = 3.7 Hz, H-4´), 4.37 (s, 3H, N+CH3); 13C-NMR (100 MHz): 171.4 (C-2), 156.0 (C-5´), 152.4 (C-2´), 147.1 (C-1´´), 142.7 (C-3a), 135.0 (C-4´´), 133.5 (C-β), 130.1 (C-6), 129.0 (C-5), 128.5 (C-7a), 126.3 (C-3´´), 125.0 (C-2´´), 124.9 (C-7), 123.6 (C-3´), 117.0 (C-4), 114.5 (C-4´), 112.2 (C-α), 37.0 (N+CH3).
3-Methyl-2-{(E)-2-[5-(3-nitrophenyl)furan-2-yl]vinyl}-1,3-benzothiazolium iodide (5d). Reaction time: 120 min; yield 82%; m.p. 220-224°C (ethanol); Calc. for C20H15IN2O3S (490.32): 48.99% C, 3.08% H, 5.71% N, 6.54% S; found: 49.26% C, 3.21% H, 5.87% N, 6.65% S; UV: 449 (3.36); 1H-NMR (400 MHz): 8.76 (s, 1H, H-2´´), 8.49 (d, 1H, J(4,5) = 8.0 Hz, H-4), 8.43 (d, 1H, J(5´´,6´´) = 8.1 Hz, H-6´´), 8.27 (d, 1H, J(6,7) = 8.0 Hz, H-7), 8.26 (d, 1H, J(4´´,5´´) = 8.2 Hz, H-4´´), 8.1 (d, 1H, J(α,β) = 15.5 Hz, H-β), 7.88 (t, 1H, , J(4,5) = 8.0 Hz, J(5,6) = 7.5 Hz, H-6), 7.83 (t, 1H, J(4´´,5´´) = 8.2 Hz, J(5´´,6´´) = 8.1 Hz, H-5´´), 7.83 (d, 1H, J(α,β) = 15.5 Hz, H-α), 7.79 (t, 1H, J(5,6) = 7.5 Hz, J(6,7) = 8.0 Hz, H-5), 7.65 (d, 1H, J(3´,4´) = 3.7 Hz, H-3´ ), 7.51 (d, 1H, J(3´,4´) = 3.7 Hz, H-4´), 4.38 (s, 3H, N+CH3); 13C-NMR (100 MHz): 170.8 (C-2), 155.3 (C-5´), 151.0 (C-2´), 148.5 (C-3´´), 141.9 (C-3a), 132.9 (C-β), 130.7 (C-6´´), 130.6 (C-4´´), 130.1 (C-1´´), 129.3 (C-6), 128.2 (C-5), 127.7 (C-7a), 124.9 (C-7), 124.1 (C-5´´), 122.9 (C-3´), 116.6 (C-4), 119 (C-2´´), 112.3 (C-4´), 111 (C-α), 36.2 (N+CH3).
3-Methyl-2-{(E)-2-[5-(2-nitrophenyl)furan-2-yl]vinyl}-1,3-benzothiazolium iodide (5e). Reaction time: 7 hours (synthesised without using a catalyst); yield 37%; m.p. 240-243°C (ethanol); Calc. for C20H15IN2O3S (490.32): 48.99% C, 3.08% H, 5.71% N, 6.54% S; found: 48.66% C, 3.19% H, 5.82% N, 6.48% S; UV: 439 (3.49); 1H-NMR (360 MHz): 8.43 (d, 1H, J(4,5) = 8.7 Hz, H-4), 8.25 (d, 1H, J(6,7) = 8.6 Hz, H-7 ), 8.12 (d, 1H, J(α,β) = 15.5 Hz, H-β ), 8.1 (d, 1H, J(5´´,6´´) = 7.9 Hz, H-6´´), 8.02 (d, 1H, J(3´´,4´´) = 8.1 Hz, H-3´´), 7.85 (t, 1H, J(4,5) = 8.7 Hz, J(5,6) = 7.7 Hz, H-6), 7.84 (t, 1H, J(4´´,5´´) = 8.6 Hz, J(5´´,6´´) = 7.9 Hz, H-5´´), 7.74 (t, 1H, J(3´´,4´´) = 8.1 Hz, J(4´´,5´´) = 8.6 Hz, H-4´´), 7,70 (t, J(5,6) = 7.7 Hz, J(6,7) = 8.6 Hz, 1H, H-5), 7.51 (d, 1H, J(α,β) = 15.5 Hz, H-α), 7.48 (d, 1H, J(3´,4´) = 3.7 Hz, H-3´), 7.22 (d, 1H, J(3´,4´) = 3.7 Hz, H-4´), 4,30 (s, 3H, N+CH3); 13C-NMR (100 MHz): 171 (C-2), 152.9 (C-5´), 151.8 (C-2´), 147.7 (C-2´´), 142.4 (C-3a), 133.3 (C-β), 133.3 (C-5´´), 131.3 (C-4´´), 130.1 (C-6´´), 129.9 (C-6), 128.9 (C-5), 128.3 (C-7a), 124.8 (C-3´´), 124.7 (C-7), 122.5 (C-3´), 122 (C-1´´), 117.2 (C-4), 114.3 (C-4´), 111.5 (C-α), 36.3 (N+CH3).
3-Methyl-2-((E)-2-{5-[3-(trifluoromethyl)phenyl]furan-2-yl}vinyl)-1,3-benzothiazolium iodide (5f). Reaction time: 150 min; yield 46%; m.p. 242-246°C (methanol); Calc. for C21H15F3INOS (513.32): 49.14% C, 2.95% H, 2.73% N, 6.25% S; found: 49.30% C, 3.01% H, 2.69% N, 6.22% S; UV: 449 (3.32); 1H-NMR (400 MHz): 8.52 (d, 1H, J(4,5) = 8.0 Hz, H-4), 8.29 (d, 1H, J(5´´,6´´) = 8.2 Hz, H-6´´), 8.33 (s, 1H, H-2´´), 8.26 (d, 1H, J(6,7) = 8.2 Hz, H-7), 8.17 (d, 1H, J(α,β) = 15.4 Hz, H-β ), 7.85 (t, 1H, J(4,5) = 8.0 Hz, J(5,6) = 8.0 Hz, H-6), 7.82 (t, 1H, J(5,6) = 8.0 Hz, J(6,7) = 8.2 Hz, H-5 ), 7.76 (d, 1H, J(4´´,5´´) = 7.9 Hz, H-4´´), 7,72 (d, 1H, J(α,β) = 15.4 Hz, H-α) 7.69 (t, 1H, J(4´´,5´´) = 7.9 Hz, J(5´´,6´´) = 8.2 Hz, H-5´´), 7.59 (d, 1H, J(3´,4´) = 3.7 Hz, H-3´), 7.55 (d, 1H, J(3´,4´) = 3.7 Hz, H-4´), 4.50 (s, 3H, N+CH3); 13C-NMR (100 MHz): 171.4 (C-2), 155.8 (C-5´), 151.0 (C-2´), 143.2 (C-3a), 134.1 (C-β), 130.9 (C-5´´), 130.1 (CF3), 129.5 (C-6), 128.9 (C-6´´), 128.1 (C-5), 127.9 (C-7a), 126.1 (C-4´´), 124.8 (C-7), 123.7 (C-3´), 122.2 (C-1´´), 117.1 (C-4), 112.0 (C-4´), 110.5 (C-α), 37.1 (N+CH3).
2-{(E)-2-[5-(2-Bromophenyl)furan-2-yl]vinyl}-3-methyl-1,3-benzothiazolium iodide (5g). Reaction time: 60 min; yield 60%; m.p. 215-219°C (ethanol); Calc. for C20H15BrINOS (524.21): 45.82% C, 2.88% H, 15.24% Br, 2.67% N, 6.12% S; found: 45.96% C, 2.79% H, 15.31% Br, 2.59% N, 6.20% S; UV: 449 (3.44); 1H-NMR (400 MHz): 8.62 (d, 1H, J(4,5) = 8.0 Hz, H-4), 8.44 (d, 1H, J(6,7) = 8.0 Hz, H-7 ), 8.35 (d, 1H, J(5´´,6´´) = 7.8 Hz, H-6´´), 8.33 (d, 1H, J(α,β) = 15.5 Hz, H-β), 8.06 (d, 1H, J(4´´,5´´) = 7.7 Hz, H-5´´), 7.97 (t, 1H, J(3´´,4´´) = 8.0 Hz, J(4´´,5´´) = 7.7 Hz, H-4´´), 7.90 (d, 1H, J(α,β) = 15.5 Hz, H-α), 7.77 (t, 1H, J(4,5) = 8.4 Hz, J(5,6) = 7.7 Hz, H-6), 7.72 (d, 1H, J(3´,4´) = 3.7 Hz, H-3´), 7.69 (d, 1H, J(3´,4´) = 3.7 Hz, H-4´), 7.59 (t, 1H, J(5,6) = 7.7 Hz, J(6,7) = 8.0 Hz, H-5) 4.53 (s, 3H, N+CH3); 13C-NMR (100 MHz): 171.2 (C-2), 155.6 (C-5´), 150.7 (C-2´), 142.4 (C-3a), 134.9 (C-β), 133.5 (C-5´´), 131.3 (C-4´´), 130.3 (C-6´´), 129.8 (C-6), 129.4 (C-2´´), 128.7 (C-3´´), 128.6 (C-5), 128.1 (C-7a), 123.5 (C-7), 122.9 (C-3´), 120 (C-1´´), 117.1 (C-4), 114.3 (C-4´), 111.2 (C-α), 36.7 (N+CH3).
2-{(E)-2-[5-(2,4-Dichlorophenyl)furan-2-yl]vinyl}-3-methyl-1,3-benzothiazolium iodide (5h). Reaction time: 60 min; yield: 86 %; m.p. 248-253°C (ethanol); Calc. for C20H14Cl2INOS (514.21): 46.72% C, 2.74% H, 13.79% Cl, 24.68% I, 2.72% N, 3.11% O, 6.24% S; found: 46.72% C, 2.74% H, 13.79% Cl, 2.72% N, 6.24% S; UV: 449 (3.59); 1H-NMR (400 MHz): 8.35 (d, 1H, J(4,5) = 8.4 Hz, H-4), 8.30 (d, 1H, J(5´´,6´´) = 8.6 Hz, H-6´´ ), 8.25 (d, 1H, J(6,7) = 8.0 Hz, H-7 ), 8.15 (d, 1H, J(α,β) = 15.5 Hz, H-β), 7.88 (t, 1H, J(4,5) = 8.4 Hz, J(5,6) = 7.6 Hz, H-6), 7.84 (s, 1H, H-3´´), 7.79 (t, 1H, J(5,6) = 7.6 Hz, J(6,7) = 8.0 Hz, H-5), 7.77 (d, 1H, J(α,β) = 15.5 Hz, H-α), 7.64 (d, 1H, J(5´´,6´´) = 8.6 Hz, H-5´´), 7.53 (d, 1H, J(3´,4´) = 3.8 Hz, H-3´), 7.50 (d, 1H, J(3´,4´) = 3.8 Hz, H-4´), 4.36 (s, 3H, N+CH3); 13C-NMR (100 MHz): 170.7 (C-2), 152.6 (C-5´), 150.2 (C-2´), 141.9 (C-3a), 134.1 (C-4´´), 132.8 (C-β), 130.7 (C-2´´), 130.4 (C-5´´), 130 (C-3´´), 129.3 (C-6), 128.2 (C-6´´), 127.8 (C-5), 127.7 (C-7a), 125.8 (C-1´´), 124.1 (C-7), 122.5 (C-3´), 116.6 (C-4), 115.5 (C-4´), 111.1 (C-α), 36.2 (N+CH3).
2-{(E)-2-[5-(4-Chlorophenyl)furan-2-yl]vinyl}-3-ethyl-1,3-benzothiazolium iodide (6a). Reaction time: 150 min; yield 62%; m.p. 245-246°C (methanol); Cal. for C21H17ClINOS (493.79): 51.08% C, 3.47% H, 7.18% Cl, 2.84% N, 6.49% S; found: 51.74% C, 3.55% H, 7.21% Cl, 2.79% N, 6.53% S; UV 468 (3.61); 1H-NMR (400 MHz): 8.43 (d, 1H, J(4,5) = 8.0 Hz, H-4), 8.28 (d, 1H, J(6,7) = 8.5 Hz, H-7), 8.07 (d, 2H, J(2´´,3´´) = 8.6 Hz, H-2´´, H-6´´), 8.14 (d, 1H, J(α,β) = 15.4 Hz, H-β), 7.87 (t, 1H, J(4,5) = 8.0 Hz, J(5,6) = 7.8 Hz, H-6), 7.78 (t, 1H, J(5,6) = 7.8 Hz, J(6,7) = 8.5 Hz, H-5), 7.71 (d, 1H, J(α,β) = 15.4 Hz, H-α), 7.61 (d, 2H, J(2´´,3´´) = 8.6 Hz, H-3´´, H-5´´), 7.50 (d, 1H, J(3´,4´) = 3.7 Hz, H-3´), 7.43 (d, 1H, J(3´,4´) = 3.7 Hz, H-4´), 4.97 (q, 2H, N+CH2), 1.49 (t, 3H, CH3); 13C-NMR (100 MHz): 171.4 (C-2), 158.1 (C-5´), 151.4 (C-2´), 141.9 (C-3a), 135.1 (C-4´´), 134.6 (C-β), 130.4 (C-6), 130.1 (C-2´´), 129.2 (C-5), 129 (C-7a), 128.4 (C-1´´), 127.7 (C-3´´), 125.4 (C-7), 124.8 (C-3´), 117 (C-4), 112.1 (C-4´), 110.2 (C-α), 45.3 (N+CH2), 15.1 (CH3).
2-{(E)-2-[5-(4-Bromophenyl)furan-2-yl]vinyl}-3-ethyl-1,3-benzothiazolium iodide (6b). Reaction time: 180 min; yield 45 %; m.p. 248-249°C (methanol); Calc. for C21H17BrINOS (538.24): 46.86% C, 3.18% H, 14.85% Br, 2.60% N, 5.96% S; found: 46.80% C, 3.08% H, 14.69% Br, 2.62% N, 5.82% S; UV 468 (3.61); 1H-NMR (400 MHz): 8.43 (d, 1H, J(4,5) = 8.0 Hz, H-4), 8.27 (d, 1H, J(6,7) = 8.4 Hz, H-7), 7.98 (d, 2H, J(2´´,3´´) = 8.6 Hz, H-2´´, H-6´´), 8.11 (d, 1H, J(α,β) = 15.4 Hz, H-β), 7.85 (t, 1H, J(5,6) = 7.8 Hz, J(6,7) = 8.4 Hz, H-6), 7.76 (t, 1H, J(4,5) = 8.0 Hz, J(5,6) = 7.8 Hz, H-5), 7.71 (d, 1H, J(α,β) = 15.4 Hz, H-α), 7.70 (d, 2H, J(2´´,3´´) = 8.6 Hz, H-3´´, H-5´´), 7.49 (d, 1H, J(3´,4´) = 3.7 Hz, H-3´), 7.43 (d, 1H, J(3´,4´) = 3.7 Hz, H-4´), 4.98 (q, 2H, N+CH2), 1,47 (t, 3H, CH3); 13C-NMR (100 MHz): 171.5 (C-2), 158.1 (C-5´), 151.5 (C-2´), 141.9 (C-3a), 134.6 (C-β), 133.0 (C-2´´), 130.4 (C-6), 129.2 (C-5), 129 (C-7a), 128.7 (C-4´´), 127.9 (C-3´´), 125.4 (C-7), 124.8 (C-3´), 123.8 (C-1´´), 117.4 (C-4), 112.1 (C-4´), 110.3 (C-α), 45.3 (N+CH2), 15.1 (CH3).
3-Ethyl-2-{(E)-2-[5-(4-nitrophenyl)furan-2-yl]vinyl}-1,3-benzothiazolium iodide (6c). Reaction time: 220 min; yield 79%; m.p. 265-268°C (ethanol); Calc. for C21H17IN2O3S (504.34): 50.01% C, 3.40% H, 5.55% N, 6.36% S; found: 50.08% C, 3.45% H, 5.61% N, 6.42% S; UV: 458 (3.57); 1H-NMR (400 MHz): 8.46 (d, 1H, J(4,5) = 8.9 Hz, H-4), 8.35 (d, 2H, J(2´´,3´´) = 8.9 Hz, H-3´´, H-5´´), 8.29 (d, 2H, J(2´´,3´´) = 8.9 Hz, H-2´´, H-6´´), 8.29 (d, 1H, J(6,7) = 8.9 Hz, H-7), 8.17 (d, 1H, J(α,β) = 15.5 Hz, H-β), 7.88 (t, 1H, J(4,5) = 8.9 Hz, J(5,6) 7.6 Hz, H-6), 7.80 (t, 1H, J(5,6) = 7.6 Hz, J(6,7) = 8.9 Hz, H-5), 7.71 (d, 1H, J(α,β) = 15.5 Hz, H-α), 7.66 (d, 1H, J(3´,4´) = 3.7 Hz, H-3´), 7.55 (d, 1H, J(3´,4´) = 3.7Hz, H-4´), 5.01 (q, 2H, N+CH2), 1.51 (t, 3H, CH3); 13C-NMR (100 MHz): 170.3 (C-2), 155.3 (C-5´), 151.6 (C-2´), 146.9 (C-1´´), 142.8 (C-3a), 134.1 (C-4´´), 133.3 (C-β), 129.5 (C-6), 128.3 (C-5), 128.2 (C-7a), 125.6 (C-3´´), 124.3 (C-2´´), 124.3 (C-7), 123.1 (C-3´), 116.5 (C-4), 113.7 (C-4´), 110.7 (C-α), 44.4 (N+CH2), 14.1 (CH3).
3-Ethyl-2-{(E)-2-[5-(3-nitrophenyl)furan-2-yl]vinyl}-1,3-benzothiazolium iodide (6d). Reaction time: 90 min; yield 74%; m.p. 246-248°C (ethanol); Calc. for C21H17IN2O3S (504.34): 50.01% C, 3.40% H, 5.55% N, 6.36% S; found: 49.89% C, 3.35% H, 5.48% N, 6.41% S; UV: 449 (3.36); 1H-NMR (400 MHz): 8.75 (s, 1H, H-2´´), 8.49 (d, 1H, J(4,5) = 8.0 Hz, H-4), 8.43 (d, 1H, J(5´´,6´´) = 8.0 Hz, H-6´´), 8.31 (d, 1H, J(4´´,5´´) = 7.9 Hz, H-4´´), 8.27 (d, 1H, J(6,7) = 8.5 Hz, H-7), 8.2 (d, 1H, J(α,β) = 15.4 Hz, H-β), 7.88 (t, 1H, J(4,5) = 8.0 Hz, J(5,6) = 7.7 Hz, H-6), 7.85 (t, 1H, J(4´´,5´´) = 7.9 Hz, J(5´´,6´´) = 8.0 Hz, H-5´´), 7.80 (d, 1H, J(α,β) = 15.4 Hz, H-α), 7.80 (t, 1H, J(5,6) = 7.7 Hz, J(6,7) = 8.5 Hz, H-5), 7.66 (d, 1H, J(3´,4´) = 3.7 Hz, H-3´), 7.55 (d, 1H, J(3´,4´) = 3.7 Hz, H-4´), 4.99 (q, 2H, N+CH2), 1.51 (t, 3H, CH3); 13C-NMR (100 MHz): 170.5 (C-2), 155.4 (C-5´), 151.0 (C-2´), 148.5 (C-3´´), 140.8 (C-3a), 133.5 (C-β), 130.7 (C-4´´), 130.6 (C-1´´), 129.4 (C-6), 128.2 (C-5), 128.1 (C-7a), 124.3 (C-5´´), 123.5 (C-7), 123.0 (C-3´´), 119.0 (C-2´´), 116.5 (C-4), 112.4 (C-4´), 110.7 (C-α), 44.3 (N+CH2), 14.0 (CH3).
3-Ethyl-2-{(E)-2-[5-(2-nitrophenyl)furan-2-yl]vinyl}-1,3-benzothiazolium iodide (6e). Reaction time: 190 min; yield 46%; m.p. 227-231°C (ethanol); Calc. for C21H17IN2O3S (504.34): 50.01% C, 3.40% H, 5.55% N, 6.36% S; found: 50.21% C, 3.42% H, 5.61% N, 6.41% S; UV: 439 (3.47); 1H-NMR (400 MHz): 8.45 (d, 1H, J(4,5) = 8.0 Hz, H-4), 8.32 (d, 1H, J(6,7) = 8.4 Hz, H-7 ), 8.16 (d, 1H, J(α,β) = 15.5 Hz, H-β ), 8.1 (d, 1H, J(5´´,6´´) = 7.7 Hz, H-6´´), 8.01 (d, 1H, J(3´´,4´´) = 7.9 Hz, H-3´´), 7.88 (t, 1H, J(4,5) = 8.0 Hz, J(5,6) = 7.7 Hz, H-6), 7.84 (t, 1H, J(4´´,5´´) = 8.8 Hz, J(5´´,6´´) = 7.7 Hz, H-5´´), 7.80 (t, 1H, J(3´´,4´´) = 7.8 Hz, J(4´´,5´´) = 8.8 Hz, H-4´´), 7.72 (t, J(5,6) = 7.7 Hz, J(6,7) = 8.4 Hz, 1H, H-5), 7.50 (d, 1H, J(α,β) = 15.5 Hz, H-α), 7.50 (d, 1H, J(3´,4´) = 3.7, H-3´), 7.29 (d, 1H, J(3´,4´) = 3.7 Hz, H-4´), 5.01(q, 2H, N+CH2), 1.51 (t, 3H, CH3); 13C-NMR (100 MHz): 169.9 (C-2), 152.3 (C-5´), 151.2 (C-2´), 147.1 (C-2´´), 140.8 (C-3a), 133.1 (C-β), 132.5 (C-5´´), 130.7 (C-4´´), 129.5 (C-6), 129.2 (C-6´´), 128.3 (C-5), 128.2 (C-7a), 124.4 (C-3´´), 124.0 (C-7), 122.0 (C-3´), 121.2 (C-1´´), 116.4 (C-4), 113.6 (C-4´), 110.52 (C-α), 44.3 (N+CH2), 13.8 (CH3).
3-Ethyl-2-((E)-2-{5-[3-(trifluoromethyl)phenyl]furan-2-yl}vinyl)-1,3-benzothiazolium iodide (6f). Reaction time: 100 min; yield 58%; m.p. 170-174°C (methanol); Calc. for C22H17F3INOS (527.34): 50.11% C, 3.25% H, 2.66% N, 6.08% S; found: 50.22% C, 3.31% H, 2.72% N, 6.11% S; UV: 453 (3.24); 1H-NMR (400 MHz): 8.47 (d, 1H, J(4,5) = 8.0 Hz, H-4), 8.35 (d, 1H, J(5´´,6´´) = 7.6 Hz, H-6´´), 8.33 (s, 1H, H-2´´), 8.31 (d, 1H, J(6,7) = 8.7 Hz, H-7), 8.17 (d, 1H, J(α,β) = 15.2 Hz, H-β ), 7.85 (t, 1H, J(4,5) = 8.0 Hz, J(5,6) = 7.6 Hz, H-6), 7.8 (t, 1H, J(5,6) = 7.6 Hz, J(6,7) = 8.7 Hz, H-5), 7.78 (d, 1H, J(4´´,5´´) = 7.7 Hz, H-4´´), 7,78 (d, 1H, J(α,β) = 15.2 Hz, H-α) 7.77 (t, 1H, J(4´´,5´´) = 7.7 Hz, J(5´´,6´´) = 7.6 Hz, H-5´´), 7.61 (d, 1H, J(3´,4´) = 3.7 Hz, H-3´), 7.55 (d, 1H, J(3´,4´ ) = 3.7 Hz, H-4´), 4.99 (q, 2H, N+CH2), 1.50 (t, 3H, CH3); 13C-NMR (100 MHz): 170.6 (C-2), 156.3 (C-5´), 150.9 (C-2´), 141.0 (C-3a), 133.7 (C-β), 130.3 (C-5´´), 129.9 (d, CF3), 129.5 (C-6), 128.6 (C-6´´), 128.3 (C-5), 128.2 (C-7a), 125.7 (C-4´´), 124.4 (C-7), 123.4 (C-3´), 122.6 (C-1´´), 116.5 (C-4), 112.0 (C-4´), 110.1 (C-α), 44.4 (N+CH2), 14.1 (CH3).
2-{(E)-2-[5-(2-Bromophenyl)furan-2-yl]vinyl}-3-ethyl-1,3-benzothiazolium iodide (6g). Reaction time: 90 min; yield 47 %; m.p. 235-237°C (methanol); Calc. for C21H17BrINOS (538.24); 46.86% C, 3.18% H, 15.24% Br, 2.67% N, 6.12% S; found: 46.95% C, 3.06% H, 15.32% Br, 2.74% N, 6.09% S; UV: 449 (3.65); 1H-NMR (400 MHz): 8.44 (d, 1H, J(4,5) = 7.9 Hz, H-4), 8.30 (d, 1H, J(6,7) = 8.4 Hz, H-7), 8.18 (d, 1H, J(α,β) = 15.5 Hz, H-β), 8.1 (d, 1H, J(5´´,6´´) = 7.9 Hz, H-6´´), 7.84 (t, 1H, J(4´´,5´´) = 7.6 Hz, J(5´´,6´´) = 7.9 Hz, H-5´´), 7.79 (t, 1H, J(3´´,4´´) = 8.0 Hz, J(4´´,5´´) 7.6 Hz, H-4´´), 7.70 (d, 1H, J(α,β) = 15.5 Hz, H-α), 7.59 (t, 1H, J(4,5) = 7.9 Hz, J(5,6) = 8.0 Hz, H-6), 7.40 (t, 1H, J(5,6) = 8.0 Hz, J(6,7) = 8.4 Hz, H-5), 7.55 (d, 1H, J(3´,4´) = 3.7 Hz, H-3´), 7.52 (d, 1H, J(3´,4´) = 3.7 Hz, H-4´), 4.96 (q, 2H, N+CH2), 1.49 (t, 3H, CH3); 13C-NMR (100 MHz): 171.0 (C-2), 155.7 (C-5´), 150.7 (C-2´), 141.3 (C-3a), 133.8 (C-β), 132.5 (C-5´´), 131.3 (C-4´´), 130.7 (C-6´´), 129.4 (C-6), 129.3 (C-2´´), 128.7 (C-3´´), 128.7 (C-7a), 128.6 (C-5), 124.8 (C-7), 122.9 (C-3´), 120.0 (C-1´´), 116.9 (C-4), 115.1 (C-4´), 110.5 (C-α), 44.8 (N+CH2), 14.5 (CH3).
2-{(E)-2-[5-(2,4-Dichlorophenyl)furan-2-yl]vinyl}-3-ethyl-1,3-benzothiazolium iodide (6h). Reaction time: 130 min; yield: 88 %, m.p. 260-263°C (methanol); Calc. for C21H16Cl2INOS (528.23): 47.75% C, 3.05% H, 13.42% Cl, 2.65% N, 6.07% S; found: 47.90% C, 3.15% H, 13.46% Cl, 2.71% N, 6.11% S; UV: 449 (3.59); 1H-NMR (400 MHz): 8.44 (d, 1H, J(4,5) = 8.1 Hz, H-4), 8.30 (d, 1H, J(6,7) = 8.5 Hz, H-7), 8.27 (d, 1H, J(5´´,6´´) = 8.8 Hz, H-6´´), 8.17 (d, 1H, J(α,β) = 15.5 Hz, H-β), 7.87 (t, 1H, J(4,5) = 8.1 Hz, J(5,6) = 7.7 Hz, H-6), 7.83 (s, 1H, H-3´´), 7.80 (t, 1H, J(5,6) = 7.7 Hz, J(6,7) = 8.5 Hz, H-5), 7.75 (d, 1H, J(α,β) = 15.5 Hz, H-α), 7.64 (d, 1H, J(5´´,6´´) = 8.8 Hz, H-5´´), 7.54 (br s, 2H, H-3´, H-4´), 4.99 (q, 2H, N+CH2), 1.48 (t, 3H, CH3); 13C-NMR (100 MHz): 170.4 (C-2), 152.9 (C-5´), 150.2 (C-2´), 140.8 (C-3a), 134.1 (C-4´´), 133.4 (C-β), 130.8 (C-2´´), 130.4 (C-5´´), 130.1 (C-3´´), 129.5 (C-6), 128.1 (C-6´´), 128.1 (C-7a), 127.9 (C-5), 125.9 (C-1´´), 124.3 (C-7), 122 (C-3´), 116.4 (C-4), 113.6 (C-4´), 110.5 (C-α), 44.3 (N+CH2), 14 (CH3).
3-Benzyl-2-{(E)-2-[5-(4-chlorophenyl)furan-2-yl]vinyl}-1,3-benzothiazolium bromide (7a). Reaction time: 70 min; yield: 91%; m.p. 232-235°C; Calc. for C26H19BrClNOS (508.85): 61.37% C, 3.76% H, 15.70% Br, 6.97% Cl; found: 61.21% C, 3.63% H, 15.81% Br, 7.06% Cl; UV: 478 (3.96); 1H-NMR (500 MHz): 8.55(d, 1H, J(4,5) = 8.0 Hz, H-4), 8.24 (d, 1H, J(6,7) = 8.5 Hz, H-7), 8.00 (d, 2H, J(2´´,3´´) = 8.6 Hz, H-2´´, H-6´´), 8.26 (d, 1H, J(α,β) = 15.3 Hz, H-β), 7.82 (t, 1H, J(4,5) = 8.0 Hz, J(5,6) = 7.8 Hz, H-6), 7.84 (t, 1H, J(5,6) = 7.8 Hz, J(6,7) = 8.5 Hz, H-5), 7.93 (d, 1H, J(α,β) = 15.4 Hz, H-α), 7.63 (d, 2H, J(2´´,3´´) = 8.6 Hz, H-3´´, H-5´´), 7.58 (d, 1H, J(3´,4´) = 3.7 Hz, H-4´), 7.47 (d, 1H, J(3´,4´) = 3.7 Hz, H-3´), 6.34 (s, 2H, N+CH2Ph), 7.40-7.44 (m, 4H, ArH); 13C-NMR (125 MHz): 171.78 (C-2), 157.44 (C-5´), 150.59 (C-2´), 141.44 (C-3a), 134.29 (C-4´´), 134.25 (C-β), 129.64 (C-6), 129.26 (C-3´´), 128.13 (C-7a), 128.36 (C-5), 127.49 (C-1´´), 126.81 (C-2´´), 124.69 (C-4), 124.54 (C-4´), 116.89 (C-7), 111.38 (C-3´), 109.63 (C-α), 51.46 (N+CH2Ph), 134.15, 129.26, 128.61, 127.11.
3-Benzyl-2-{(E)-2-[5-(4-bromophenyl)furan-2-yl]vinyl}-1,3-benzothiazolium bromide (7b). Reaction time: 100 min; yield: 87%; m.p. 225-228°C; Calc. for C26H18Br2NOS (553.31): 56.44% C, 3.46% H, 28.88% Br, 2.53% N, 5.80% S; found: 56.62% C, 3.35% H, 29.21% Br, 2.74% N, 6.12% S; UV: 478 (3.67); 1H-NMR (500 MHz): 8.55 (d, 1H, J(4,5) = 8.0 Hz, H-4), 8.23 (d, 1H, J(6,7) = 8.4 Hz, H-7), 8.32 (d, 1H, J(α,β) = 15.4 Hz, H-β), 8.00 (d, 2H, J(2´´,3´´) = 8.6 Hz, H-2´´, H-6´´), 7.86 (t, 1H, J(4,5) = 8.0 Hz, J(5,6) = 7.8 Hz, H-6), 7.82 (t, 1H, J(5,6) = 7.8 Hz, J(6,7) = 8.4 Hz, H-5), 7.79 (d, 2H, J(2´´,3´´) = 8.6 Hz, H-3´´, H-5´´), 7.71 (d, 1H, J(α,β) = 15.4 Hz, H-α), 7.56 (d, 1H, J(3´,4´) = 3.7 Hz, H-4´), 7.48 (d, 1H, J(3´,4´) = 3.7 Hz, H-3´), 6.34 (s, 2H, N+CH2Ph); 13C-NMR (125 MHz): 171.84 (C-2), 157.49 (C-5´), 150.59 (C-2´), 141.44 (C-3a), 134.26 (C-β), 132.27 (C-3´´), 129.67 (C-6), 128.64 (C-5), 128.13 (C-7a), 127.84 (C-1´´),127.11 (C-2´´), 124.65 (C-4), 124.50 (C-4´), 123.12 (C-4´´), 116.89 (C-7), 114.43 (C-3´), 109.68 (C-α), 51.48 (N+CH2Ph), 129.29, 128.72, 127.14.
3-Benzyl-2-{(E)-2-[5-(4-nitrophenyl)furan-2-yl]vinyl}-1,3-benzothiazolium bromide (7c). Reaction time: 130 min; yield: 64%; m.p. 235-240°C; Calc. for C26H19BrN2O3S (519.41): 60.12% C, 3.69% H, 15.38% Br, 5.39% N, 6.17% S; found: 60.44% C, 3.45% H, 15.37% Br, 5.62% N, 6.22% S; UV: 463 (3.58); 1H-NMR (500 MHz): 8.54 (d, 1H, J(4,5) = 8.6 Hz, H-4), 8.40 (d, 2H, J(2´´,3´´) = 8.9 Hz, H-3´´, H-5´´), 8.31 (d, 2H, J(2´´,3´´) = 8.9 Hz, H-2´´, H-6´´), 8.27 (d, 1H, J(6,7) = 8.6 Hz, H-7), 8.32 (d, 1H, J(α,β) = 15.5 Hz, H-β), 7.88 (t, 1H, J(4,5) = 8.9 Hz, J(5,6) 7.6 Hz, H-5), 7.82 (t, 1H, J(5,6) = 7.6 Hz, J(6,7) = 8.6 Hz, H-6), 8.05 (d, 1H, J(α,β) = 15.5 Hz, H-α), 7.71 (d, 1H, J(3´,4´) = 3.7Hz, H-4´), 7.60 (d, 1H, J(3´,4´) = 3.7 Hz, H-3´), 6.38 (s, 2H, N+CH2Ph); 13C-NMR (125 MHz): 171.85 (C-2), 155.78 (C-5´), 151.85 (C-2´), 147.27 (C-4´´), 141.48 (C-3a), 134.35 (C-1´´), 134.12 (C-β), 129.82 (C-6), 128.64 (C-5), 128.37 (C-7a), 125.84, (C-2´´), 124.77 (C-4), 124.59 (C-3´´), 117.09 (C-7), 123.85 (C-3´), 114.16 (C-4´), 111.2 (C-α), 51.66 (N+CH2Ph), 129.34, 128.72, 127.18.
3-Benzyl-2-{(E)-2-[5-(3-nitrophenyl)furan-2-yl]vinyl}-1,3-benzothiazolium bromide (7d). Reaction time: 100 min; yield: 86%; m.p. 245-247°C; Calc. for C26H19BrN2O3S (519.41): 60.12% C, 3.69% H, 15.38% Br, 5.39% N, 6.17% S; found: 60.13% C, 3.52% H, 15.43% Br, 5.56% N, 6.24% S; UV: 458 (3.73); 1H-NMR (300 MHz): 8.74 (s, 1H, H-2´´), 8.50 (d, 1H, J(4,5) = 7.5 Hz, H-4), 8.44-8.48 (m, 3H, Harom), 8.27 (d, 1H, J(5´´,6´´) = 7.5 Hz, H-6´´), 8.26 (d, 1H, J(α,β) = 15.6 Hz, H-β), 7.94 (d, 1H, J(α,β) = 15.6 Hz, H-α ), 7.78-7.86 (m, 3H, Harom), 7.66 (d, 1H, J(3´,4´) = 3.6 Hz, H-3´), 7.42 (d, 1H, J(3´,4´) = 3.6 Hz, H-4´), 7.37 – 7.39 (m, 4H, Harom), 6.32 (s, 2H, CH2Ph); 13C-NMR (75 MHz): 171.65 (C-2), 155.64 (C-5´), 151.0 (C-2´), 148.55 (C-3´´), 141.37 (C-3a), 134.01 (C-β), 130.81 (C-6´´), 130.08 (C-4´´), 129.63 (C-1´´), 128.15 (C-6), 127.00 (C-7a), 124.56 (C-7), 123.73 (C-5´´), 123.65 (C-3´), 116.83 (C-4´), 110.56 (C-α), 51.4 (CH2Ph), 128.55, 128.40, 119.06.
3-Benzyl-2-{(E)-2-[5-(2-nitrophenyl)furan-2-yl]vinyl}-1,3-benzothiazolium bromide (7e). Reaction time: 75 min; yield: 68%; m.p. 194-198°C; Calc. for C26H19BrN2O3S (519.41): 60.12% C, 3.69% H, 15.38% Br, 5.39% N, 6.17% S; found: 60.32% C, 3.65% H, 15.47% Br, 5.61% N, 6.14% S; UV: 449 (3.62); 1H-NMR (300 MHz): 8.49 (d, 1H, J(4,5) = 8.5 Hz, H-4), 8.31 (d, 1H, J(6,7) = 8.3 Hz, H-7), 8.21 – 8.29 (m, 5H, Harom), 8.19 (d, 1H, J(α,β) = 15.5 Hz, H-β), 7.98 – 8.06 (m, 6H, Harom), 7.53 (d, 1H, J(α,β) = 15.5 Hz, H-α), 7.39 (d, 1H, J(3´,4´) = 3.7 Hz, H-3´), 7.24 (d, 1H, J(3´,4´) = 3.7 Hz, H-4´), 6.20 (s, 2H, CH2Ph); 13C-NMR (75 MHz): 171.23 (c-2), 154.98 (C-5´), 151.16 (C-2´), 149.11 (C-3´´), 141.49 (C-3a), 134.11 (C-β), 130.91 (C-6´´), 130.22 (C-4´´), 129.68 (C-1´´), 128.40 (C-6), 128.01 (C-7a), 124.70 (C-7), 123.33 (C-5´´), 123.65 (C-3´), 116.78 (C-4´), 111.00 (C-α), 51.38 (CH2Ph), 128.77, 128.70, 119.12.
3-Benzyl-2-((E)-2-{5-[3-(trifluoromethyl)phenyl]furan-2-yl}vinyl)-1,3-benzothiazolium bromide (7f). Reaction time: 90 min; yield: 66%; m.p. 250-254°C; Calc. for C27H19BrF3NOS (542.41): 59.79% C, 3.53% H, 14.73% Br, 2.58% N, 5.91% S; found: 60.10% C, 3.43% H, 14.86% Br, 2.64% N, 6.05% S; UV: 463 (3.58); 1H-NMR (300 MHz): 8.49 (d, 1H, J(4,5) = 8.1 Hz, H-4), 8.31 (d, 1H, J(6,7) = 8.3 Hz, H-7), 8.21-8.29 (m, 5H, Harom), 8.19 (d, 1H, J(α,β) = 15.7 Hz, H-β), 7.98 – 8.06 (m, 6H, Harom), 7.79 (d, 1H, J(α,β) = 15.7 Hz, H-α), 7.53 (d, 1H, J(3´,4´) = 3.6 Hz, H-3´), 7.39 (d, 1H, J(3´,4´) = 3.6 Hz, H-4´), 6.20 (s, 2H, CH2Ph); 13C-NMR (75 MHz): 171.65 (C-2), 153.18 (C-5´), 150.29 (C-2´), 141.33 (C-3a), 133.91 (C-β), 130.83 (C-5´), 130.50 (C-4´´), 130.03 (C-6´´), 129.61 (C-6), 129.12 (C-2´´), 128.49 (C-3´´), 128.40 (C-7a), 128.16 (C-5), 128.81 (C-7), 124.58 (C-3´), 123.23 (C-1´), 116.83 (C-4), 115.36 (C-4´), 110.72 (C-α), 51.4 (CH2Ph), 134.28, 127.98, 126.92.
3-Benzyl-2-{(E)-2-[5-(2-bromophenyl)furan-2-yl]vinyl}-1,3-benzothiazolium bromide (7g). Reaction time: 120 min; yield: 52%; m.p. 220-224°C; Calc. for C26H18Br2NOS (553.31): 56.44% C, 3.46% H, 28.88% Br, 2.53% N, 5.80% S; found: 56.65% C, 3.33% H, 29.07% Br, 2.84% N, 6.43% S; 1H-NMR (300 MHz): 8.48 (d, 1H, J(4,5) = 8.2 Hz, H-4), 8.28 (d, 1H, J(6,7) = 8.1 Hz, H-7), 8.10-8.26 (m, 5H, Harom), 8.08 (d, 1H, J(α,β) = 15.5 Hz, H-β), 7.79 – 7.84 (m, 6H, Harom), 7.62 (d, 1H, J(α,β) = 15.5 Hz, H-α), 7.59 (d, 1H, J(3´,4´) = 3.6 Hz, H-3´), 7.53 (d, 1H, J(3´,4´) = 3.6 Hz, H-4´), 6.27 (s, 2H, CH2Ph); 13C-NMR (75 MHz): 171.68 (C-2), 155.12 (C-5´), 150.21 (C-2´), 141.36 (C-3a), 133.89 (C-β), 130.95 (C-5´), 129.82 (C-4´´), 129.60 (C-6´´), 129.01 (C-6), 128.79 (C-2´´), 128.46 (C-3´´), 128.38 (C-7a), 128.19 (C-5), 128.11 (C-7), 124.55 (C-3´), 123.11 (C-1´), 116.76 (C-4), 114.67 (C-4´), 110.24 (C-α), 51.33 (CH2Ph), 134.46, 134.23, 126.85.
3-Benzyl-2-{(E)-2-[5-(2,4-dichlorophenyl)furan-2-yl]vinyl}-1,3-benzothiazolium bromide (7h). Reaction time: 120 min; yield: 43%; m.p. 227-230°C; Calc. for C26H18BrCl2NOS (543.30): 57.48% C, 3.34% H, 13.05% Br, 14.71% Cl, 2.58% N, 5.90% S; found: 57.62% C, 3.23% H, 13.15% Br, % 14.81 Cl, 2.64% N, 5.85% S; UV: 463 (3.59); 1H-NMR (300 MHz): 8.48 (d, 1H, J(4,5) = 8.1 Hz, H-4), 8.28 (d, 1H, J(6,7) = 8.1 Hz, H-7), 8.10 – 8.26 (m, 5H, Harom), 8.08 (d, 1H, J(α,β) = 15.4 Hz, H-β), 7.78 – 8.07 (m, 6H, Harom), 7.62 (d, 1H, J(α,β) = 15.4 Hz, H-α), 7.59 (d, 1H, J(3´,4´) = 3.7 Hz, H-3´), 7.52 (d, 1H, J(3´,4´) = 3.7 Hz, H-4´), 6.27 (s, 2H, CH2Ph). δC (75 MHz): 171.65 (C-2), 153.18 (C-5´), 150.29 (C-2´), 141.33 (C-3a), 133.91(C-β), 130.83 (C-5´), 130.03 (C-4´´), 129.61 (C-6´´), 129.12 (C-6), 128.49 (C-2´´), 128.40 (C-3´´), 128.16 (C-7a), 127.98 (C-5), 126.91 (C-7), 124.56 (C-3´), 123.23 (C-1´), 116.83 (C-4), 11.36 (C-4´), 110.71 (C-α), 51.40 (CH2Ph), 134.27, 130.49, 125.81.
2-{(E)-2-[5-(Methoxycarbonyl)-4H-furo[3,2-b]pyrrol-2-yl]vinyl}-3-methyl-1,3-benzothiazolium iodide (8a). Yield 61%; m.p. 288-292°C (methanol); Calc. for C18H15IN2O3S (466.29): 46.36% C, 3.24% H, 6.01% N, 6.88% S; found: 46.51% C, 3.33% H, 6.03% N, 6.92% S. UV: 483 (3.66); 1H-NMR (500 MHz): 12.24 (s, 1H, NH), 8.42 (d, 1H, H-7), 8.25 (d, 1H, H-4), 8.11 (d, 1H, J(α,β) = 15.4 Hz, H-β), 7.88 (t, 1H, H-5), 7.79 (t, 1H, H-6), 7.63 (d, 1H, J(α,β) = 15.4 Hz, H-α), 7.48 (s, 1H, H-3´), 6.89 (s, 1H, H-6´), 4.32 (s, 3H, N+CH3), 3.87 (s, 3H, CO2CH3); 13C-NMR (125 MHz): 170.59 (C-2), 161.27 (CO2CH3), 156.07 (C-2´), 151.54 (C-6´a), 142.26 (C-3a), 134.37 (C-β), 130.79 (C-3´a), 129.2 (C-5´), 128.49 (C-6), 127.82 (C-7a), 124.1 (C-7), 121.63 (C-5), 116.86 (C-4), 109.91 (C-α), 108.8 (C-3´), 95.65 (C-6´), 52.18 (CO2CH3), 36.30 (N+CH3).
3-Benzyl-2-{(E)-2-[5-(methoxycarbonyl)-4H-furo[3,2-b]pyrrol-2-yl]vinyl}-1,3-benzothiazolium bromide (8b). Reaction time: 120 min; yield: 70%; m.p. 235-238°C; Calc. for C24H19BrN2O3S (495.39): 58.19% C, 3.87% H, 5.65% N, 6.47% S; found: 58.40% C, 3.72% H, 5.72% N, 6.54% S; UV: 497 (3.76); 1H-NMR (500 MHz): 12.30 (s, 1H, NH), 8.51 (d, 1H, J(4,5) = 8.2 Hz, H-4), 8.27 (d, 1H, J(α,β) = 15.3 Hz, H-β), 8.20 (d, 1H, J(6,7) = 8.1 Hz, H-4), 7.84 (t, 1H, H-6), 7.79 (t, 1H, H-5), 7.76 (d, 1H, J(α,β) = 15.3 Hz, H-α), 7.60 (s, 1H, H-3´), 7.44-7.36 (m, 5H, Harom), 6.86 (s, 1H, H-5´), 6.29 (s, 2H, N+CH2), 3.87 (s, 3H, CO2CH3); 13C-NMR (125 MHz): 171.35 (C-2), 160.99 (C-4´), 155.92 (C-2´), 151.69 (C-6a´), 141.41 (C-3a), 135.43 (C-β), 134.52 (C-3a´), 129.63 (C-6), 129.54 (CO2CH3), 128.32 (C-5), 127.98 (C-7a), 124.67 (C-4), 116.75 (C-7), 109.38 (C-3´), 109.02 (C-α), 95.55 (C-5´), 51.98 (CO2CH3), 51.13 (N+CH2), 133.98, 129.21, 128.47, 126.73.
3-Benzyl-2-{(E)-2-[5-(ethoxycarbonyl)-4-methylfuro[3,2-b]pyrrol-2-yl]vinyl}-1,3-benzothiazolium bromide (8c). Reaction time: 110 min; yield: 48%; m.p. 223-226°C; Calc. for C26H23BrN2O3S (523.44): 59.66% C, 4.43% H, 5.35% N, 6.13% S; found: 59.84% C, 4.20% H, 5.27% N, 6.07% S; UV: 497 (3.83); 1H-NMR (500 MHz): 8.51 (d, 1H, J(4,5) = 8.3 Hz, H-4), 8.29 (d, 1H, J(α,β) = 15.3 Hz, H-β), 8.21 (d, 1H, J(6,7) = 8.2 Hz, H-7), 7.84 (t, 1H, H-6), 7.79 (t, 1H, H-5), 7.76 (d, 1H, J(α,β) = 15.3 Hz, H-α), 7.69 (s, 1H, H-3´), 7.45-7.36 (m, 5H, Harom), 6.83 (H-6´), 6.29 (s, 2H, N+CH2), 4.31 (q, 2H, CO2CH2CH3), 4.01 (NCH3), 1.34 (t, 3H, CO2CH2CH3); 13C-NMR (125 MHz): 171.36 (C-2), 160.56 (CO2CH2CH3), 155.55 (C-2´), 149.13 (C-6a´), 141.38 (C-3a), 135.59 (C-β), 129.66 (C-6), 129.30 (C-4´), 133.94, 129.26, 128.50, 128.37 (C-5), 128.05 (C-7a), 124.60 (C-4), 116.72 (C-7), 109.36 (C-α), 108.86 (C-3´), 96.84 (C-5´), 60.59 (CO2CH2CH3), 51.17 (N+CH2), 35.08 (NCH3), 14.30 (CO2CH2CH3), 133.94, 129.26, 128.50, 126.77.
3-Benzyl-2-{(E)-2-[5-(ethoxycarbonyl)-4-benzylfuro[3,2-b]pyrrol-2-yl]vinyl}-1,3-benzothiazolium bromide (8d). Reaction time: 120 min; yield: 67%; m.p. 242-245°C; Calc. for C32H27BrN2O3S (599.54): 64.11% C, 4.54% H, 4.67% N, 5.35% S; found: 64.28% C, 4.38% H, 4.72% N, 5.41% S; UV: 497 (3.98); 1H-NMR (500 MHz): 8.49 (d, 1H, J(4,5) = 8.1 Hz, H-4), 8.27 (d, 1H, J(α,β) = 15.3 Hz, H-β), 8.21 (d, 1H, J(6,7) = 8.1 Hz, H-7), 7.85 (t, 1H, H-6), 7.79 (t, 1H, H-5), 7.76 (d, 1H, J(α,β) = 15.3 Hz, H-α), 7.52 (s, 1H, H-3´), 7.44-7.25 (m, 10H, Harom), 6.99 (s, 1H, H-5´), 6.28 (N+CH2), 5.78 (NCH2), 4.31 (q, 2H, CO2CH2CH3), 1.32 (t, 3H, CO2CH2CH3); 13C-NMR (125 MHz): 171.51 (C-2), 160.59 (CO2CH2CH3), 155.75 (C-2´), 149.46 (C-6a´), 141.44 (C-3a), 135.40 (C-β), 134.50 (C-3a´), 129.74 (C-6), 129.30 (C-4´), 128.42 (C-5), 116.81 (C-4), 109.82 (C-α), 108.98 (C-3´), 98.01(C-5´), 60.73 (CO2CH2CH3), 51.26 (N+CH2), 50.17 (NCH2), 14.25 (CO2CH2CH3), 137.68, 133.94, 129.25, 128.80, 128.54, 127.78, 127.10.
3-Benzyl-2-{(E)-2-[5-(methoxycarbonyl)-6-methoxymethylfuro[2,3-b]pyrrol-2-yl]vinyl}-1,3-benzo-thiazolium bromide (9). Reaction time: 160 min; yield: 45%; m.p. 278-282°C; Calc. for C26H23BrN2O4S (539.44): 57.89% C, 4.30% H, 5.19% N, 5.94% S; found: 58.12% C, 4.18% H, 5.27% N, 5.95% S; 1H-NMR (500 MHz): 8.48 (d, 1H, J(4,5) = 8.3 Hz, H-4), 8.30 (d, 1H, J(α,β) = 15.3 Hz, H-β), 8.22 (d, 1H, J(6,7) = 8.1 Hz, H-7), 7.87 (t, 1H, H-6), 7.81 (t, 1H, H-6), 7.68 (d, 1H, J(α,β) = 15.3 Hz, H-α), 7.67 (s, 1H, H-4´), 7.42-7.37 (m, 5H, Harom), 7.19 (s, 1H, H-3´), 6.26 (N+CH2), 5.83 (s, 2H, CH2OCH3), 3.87 (s, 3H, CO2CH3), 3.31 (s, 3H, CH2OCH3).