Page 21 of 32
The Journal of Organic Chemistry
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– 8.20 (m, 2H), 8.05 – 8.00 (m, 1H), 7.63 (ddd, J = 9.2, 5.6, 2.0 Hz, 3H), 7.19 – 7.07 (m, 2H), 4.88 (d, J =
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2.4 Hz, 2H), 2.58 (s, 1H); C{1H} NMR (101 MHz, Chloroform-d) δ 164.0, 157.9, 152.9, 149.9, 137.6,
136.9, 129.7, 128.6, 128.0, 126.0, 122.5, 122.2, 119.8, 113.3, 112.9, 111.1, 77.3, 56.6; MS (ESI), m/z (%)
381 [M]+ (100); HRMS (ESI) m/z: [M + Na]+ Calcd for C19H12N2NaO3S2 403.0187; Found 403.0181.
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(E)-3-(benzo[d]thiazol-2-ylsulfonyl)-6-phenylhex-4-en-2-one (7a). Reaction was carried out using the
described procedure with 0.050 g (0.2 mmol) of sulfone 2a. Purification using flash chromatography
(SiO2; EtOAc/petroleum ether = 1:3) and concentration of the relevant fractions provided the 7a as a
white solid (0.036 g, 49%). 1H NMR (400 MHz, Chloroform-d) δ 8.24 – 8.16 (m, 1H), 8.01 – 7.95 (m, 1H),
7.69 – 7.56 (m, 2H), 7.13 – 7.06 (m, 3H), 6.94 – 6.86 (m, 2H), 5.92 – 5.77 (m, 2H), 5.22 (d, J = 9.2 Hz,
1H), 3.35 (d, J = 6.0 Hz, 2H), 2.51 (s, 3H); 13C{1H} NMR (101 MHz, Chloroform-d) δ 196.6, 164.2, 152.6,
142.5, 138.1, 137.1, 128.6, 128.4, 128.3, 127.8, 126.5, 125.7, 122.5, 117.5, 78.0, 39.1, 31.2; MS (ESI),
m/z (%) 372 [M+1]+ (37); HRMS (ESI) m/z: [M + H]+ Calcd for C19H18NO3S2 372.0723; Found 372.0725.
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(E)-3-(benzo[d]thiazol-2-ylsulfonyl)hept-4-en-2-one (7b). Reaction was carried out using the described
procedure with 0.050 g (0.2 mmol) of sulfone 2a. Crude product proved to be unstable on SiO2. The
yield of the crude material was 0.019 g, 31%, (keto/enol = 1.7:1). Peaks attributed to enol form marked
with *; 1H NMR (400 MHz, Chloroform-d) δ(ppm): 0.84 (t, J = 7.6 Hz, 3H*), 1.00 (t, J = 7.6 Hz, 3H), 2.04
(qd, J = 7.6, 6.8, 5.2 Hz, 2H), 2.48 (dd, J = 7.6, 3.6 Hz, 1H*), 2.50 (s, 3H*), 2.52 (dd, J = 7.6, 0.4 Hz, 1H*),
2.57 (s, 3H), 5.16 (d, J = 9.2 Hz, 1H), 5.65 – 5.85 (m, 2H), 7.50 (t, J = 7.6 Hz, 1H*), 7.55 – 7.69 (m, 2H &
2H*), 7.98 – 8.04 (m, 1H & 1H*), 8.17 – 8.20 (m, 1H), 8.24 (ddd, J = 8.4, 1.6, 0.8 Hz, 1H*); HRMS (ESI)
m/z: [M + Na]+ Calcd for C14H15NNaO3S2 332.0391, found 332.0393.
General procedure for dihydropyran 9 synthesis. A vinyl-sulfone 3 (0.100 g, 0.29 mmol) was dissolved
in benzene (1.5 mL, 0.2 M) and vinyl-ether (0.278 mL, 2.9 mmol) was added in one portion. Mixture
was stirred for 24 hours. Volatilities were evaporated under reduced pressure to yield the crude
product.
2-(((4S)-2-ethoxy-6-methyl-4-phenyl-3,4-dihydro-2H-pyran-5-yl)sulfonyl)benzo[d]thiazole
(9a).
Reaction was carried out using the described procedure with 0.100 g (0.29 mmol) of vinyl-sulfone 3a.
Purification using flash chromatography (SiO2; EtOAc/petroleum ether = 1:3) and concentration of the
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relevant fractions provided the 9a as a yellow oil (0.129 g, 90%, d.r. = 1 : 1.1). H NMR (400 MHz,
Chloroform-d) δ 8.15 – 8.08 (m, 2H), 7.85 (d, J = 8.0 Hz, 1H), 7.79 (d, J = 8.0 Hz, 1H), 7.60 – 7.54 (m,
2H), 7.53 – 7.44 (m, 2H), 7.08 (bs, 5H), 7.02 (d, J = 7.2 Hz, 2H), 6.91 (t, J = 7.2 Hz, 1H), 6.84 (t, J = 7.6 Hz,
2H), 5.11 (dd, J = 6.8, 2.4 Hz, 1H), 4.95 (t, J = 6.0 Hz, 1H), 4.31 (t, J = 4.4 Hz, 1H), 4.19 (t, J = 7.6 Hz, 1H),
3.99 – 3.88 (m, 2H), 3.62 – 3.52 (m, 2H), 2.68 (bs, 3H), 2.64 (bs, 3H), 2.35 (ddd, J = 14.0, 7.6, 2.4 Hz,
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1H), 2.12 – 2.04 (m, 3H), 1.19 (t, J = 6.0 Hz, 3H), 1.16 (t, J = 6.0 Hz, 3H); C{1H} NMR (101 MHz,
Chloroform-d) δ 170.2, 169.6, 168.1, 167.8, 152.7, 152.5, 142.7, 141.6, 137.2, 136.9, 128.9, 128.6,
128.1, 127.8, 127.4, 127.2, 127.2, 127.0, 126.8, 126.4, 125.3, 125.2, 122.1, 121.9, 113.9, 110.6, 100.2,
98.7, 65.6, 65.2, 39.1, 38.5, 37.7, 35.9, 21.2, 20.7, 15.2, 15.1; MS (ESI), m/z (%) 416 [M+H]+ (62); HRMS
(ESI) m/z: [M + H]+ Calcd for C21H22NO4S2 416.0985; Found 416.0987.
2-(((4S)-6-(but-3-en-1-yl)-2-ethoxy-4-phenyl-3,4-dihydro-2H-pyran-5-yl)sulfonyl)benzo[d]thiazole (9b).
Reaction was carried out using the described procedure with 0.100 g (0.26 mmol) of vinyl-sulfone 3s.
Purification using flash chromatography (SiO2; EtOAc/petroleum ether = 1:3) and concentration of the
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relevant fractions provided the 9b as a yellow oil (0.109 g, 70%, d.r. = 1 : 1.1). H NMR (400 MHz,
Chloroform-d) δ 8.11 (t, J = 8.4 Hz, 2H), 7.85 (d, J = 8.0 Hz, 1H), 7.78 (d, J = 8.0 Hz, 1H), 7.60 – 7.53 (m,
2H), 7.53 – 7.45 (m, 2H), 7.09 (bs, 5H), 7.01 (d, J = 7.2 Hz, 2H), 6.91 (t, J = 7.2 Hz, 1H), 6.84 (t, J = 7.2 Hz,
2H), 5.97 (dddt, J = 20.8, 16.8, 10.4, 6.8 Hz, 2H), 5.19 – 5.07 (m, 3H), 5.06 – 4.98 (m, 2H), 4.96 – 4.89
(m, 1H), 4.33 (t, J = 4.8 Hz, 1H), 4.22 (t, J = 8.0 Hz, 1H), 3.94 (dqd, J = 9.6, 7.2, 2.4 Hz, 2H), 3.56 (ddq, J =
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