Page 17 of 24
The Journal of Organic Chemistry
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filtered and evaporated. The residue was resolved in acetone to remove remaining urea by filtration,
and the filtrate was evaporated. After purification by reversed phase chromatography (MeCN/H
2
O, 5%
–
5
95% MeCN, automatic flash purification system), 13 was obtained as colorless lyophilizate (222 mg,
5%). NMR spectra show a mixture of rotameres and keto-enol tautomers: R = 0.35 (silica gel,
f
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–1
CH/EtOAc, 8:2); IR (ATR) n (cm ) = 3016, 2951, 2857, 1746, 1658, 1528, 1455, 1253, 1118, 838;
3
1
1
[
α]
OH), 8.12 (dd, J = 8.2, 1.1 Hz, 1H, Ar-H3 enol), 8.10 (dd, J = 8.1, 1.1 Hz, 1H, Ar-H3 R1), 8.07 (dd, J
8.2, 1.1 Hz, 1H, Ar-H3 R2), 7.96 (d, J = 7.6 Hz, 1H, Ar-H6 R1), 7.80 (d, J = 7.8 Hz, 1H, Ar-H6
enol), 7.72 (dd, J = 8.0, 1.3 Hz, 1H, Ar-H6 R2), 7.70 (td, J = 7.6, 1.3 Hz, 1H, Ar-H5 R1), 7.63 (td, J =
.6, 1.3 Hz, 1H, Ar-H5 enol), 7.59 (td, J = 7.7, 1.3 Hz, 1H, Ar-H-5 R2), 7.50 – 7.47 (m, 1H, Ar-H3
R1), 7.47 – 7.41 (m, 1H, Ar-H3 enol), 7.35 (t, J = 7.5 Hz, 1H, Ar-H3 R2), 5.47 – 5.01 (m, 17H, H-4,
H-5, H-1‘, H-2‘, Ar-CH R1, Ar-CH enol, Ar-CH a R2), 4.97 (d, J = 18.2 Hz, 1H, Ar-CH b R2),
.94 – 4.92 (m, 1H, C-2‘‘ enol), 4.71 (s, 1H, C=CH-CONR enol), 4.55 (dd, J = 6.3, 4.0 Hz, 1H, C-2‘‘
R2), 4.47 (dd, J = 7.0, 3.3 Hz, 1H, C-2‘‘ R1), 4.25 – 4.20 (m, 1H, C-3‘‘ a enol), 4.20 – 4.17 (m, 2H, C-
D
= –74.5 (c 1.00, CHCl
3
); H NMR, COSY (600 MHz, CDCl
3
) δ (ppm) = 14.43 (s, 1H, enol-
=
7
2
2
2
2
4
2
3
‘‘ a R1 & R2), 4.04 – 3.98 (m, 3H, C-3‘‘ b), 3.76 (s, 3H, COOMe enol), 3.71 (s, 3H, COOMe R2),
.66 (s, 3H, COOMe R1), 3.64 (d, J = 16.5, 1H, CO-CH -CONR a R1), 3.62 (d, J = 16.4, 1H, CO-
-CONR b R2), 3.15 (d, J = 16.5 Hz, 1H, CO-
b R1), 2.60 (dd, J = 9.4, 5.0 Hz, 1H, H-3 R2), 2.44 (dd, J = 9.2, 5.2 Hz, 1H, H-3 R1),
3
2
2
CH
2
2
-CONR
2
2
a R2), 3.33 (d, J = 16.4 Hz, 1H, CO-CH
2
2
CH
-CONR
2.29 – 2.27 (m, 1H, H-3 enol), 1.84 – 1.65 (m, 16H, H-6, H-7a, H-9a, H-10a, H-11 R1 & enol), 1.65 –
1.57 (m, 4H, H-3‘, H-11 R2), 1.55 (dd, J = 6.4, 1.6 Hz, 3H, H-3‘), 1.53 – 1.44 (m, 2H, 2xH-8), 1.38
(dd, J = 6.4, 1.6 Hz, 3H, H-3‘), 1.37 – 1.33 (m, 2H, 1xH-8, 1xH-10b) 1.23 (s, 3H, C-2-Me R2), 1.12
(s, 3H, C-2-Me R1), 1.10 – 1.03 (m 2H, 2x H-9b), 0.93 – 0.87 (m, 13H, H-8-Me R1 & enol, C-2-Me
enol, 2xH-10b, 2x H-7b), 0.83–0.81 (m, 3H, C8-Me R2), 0.81 (s, 9H, C(CH
C(CH ), 0.76 – 0.74 (m, 1H, 1x H-7b), 0.50–0.46 (m, 1H, 1x H-9b), 0.02 (s, 3H, SiMe), –0.04 (s, 3H,
SiMe), –0.06 (s, 3H, SiMe), –0.07 (s, 3H, SiMe), –0.12 (s, 3H, SiMe), –0.13 (s, 3H, SiMe);
3
3
) ), 0.77 (s, 18H, 2x
)
3 3
1
3
1
C{ H} NMR, HSQC, HMBC (150.1 MHz, CDCl
C-1 enol), 173.9 (C=CH-CONR enol), 169.9 (COOMe enol), 169.8 (CONR
R1), 169.4 (COOMe R2), 168.7 (CONR R2), 147.8 (Ar-C2 R1), 147.44 (Ar-C2 R2), 147.39 (Ar-C2
3
) δ (ppm) = 208.1 (C-1 R2), 206.5 (C-1 R1), 183.9
(
2
2
R1), 169.5 (COOMe
2
enol), 136.7, 134.51 (Ar-C1 R2), 134.48 (Ar-C1 enol), 134.1 (Ar-C5 R1), 133.79 (Ar-C5 R2), 133.76
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