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General Procedure
for the Synthesis of Dienamide 3a
The mixture of vinyl
malononitrile 1a (1.5 mmol), aldehyde 2a (1 mmol), and Et3N (1 mmol)
in ethylene glycol (7 mL) was stirred at 40 ˚C
for 40 min. After the reaction was complete as indicated by TLC,
the reaction mixture was cooled to r.t. diluted with acid H2O
(10 mL). The resulting precipitate was filtered and subjected to
chromatographic purification over silica gel (Merck; 100-200
mesh; EtOAc-hexane = 3:7) to obtain dienamide 3a (78%) as a single diastereomer.
Spectral Data of Dienamide 3a (Table 1, Entry
1)
Off-white solid; yield 78%; mp 392 ˚C. ¹H
NMR (500 MHz, DMSO-d
6): δ = 1.55
(m, 2 H), 1.75 (m, 2 H), 2.53 (m, 4 H), 6.42 (s, 1 H), 7.21 (d, J = 8.4 Hz,
2 H), 7.38 (d, J = 8.4
Hz, 2 H), 7.53 (s, 1 H, D2O exchangeable), 7.87 (s, 1
H, D2O exchangeable). ¹³C
NMR (125 MHz, DMSO-d
6): δ = 26.0, 26.4,
29.9, 35.1, 106.6, 116.8, 127.2, 128.9, 128.9, 130.1, 131.4, 132.6,
135.0, 139.3, 164.3, 164.5. IR (KBr): νmax = 3397,
3385, 2935, 2216, 1673, 1388, 1092, 626 cm-¹.
ESI-MS: 287 [M + 1]. Anal. Calcd (%)
for C16H15ClN2O: C, 67.02; H, 5.27;
N, 9.77. Found: C, 66.97; H, 5.21; N, 9.71.
Spectral
Data of Dienamide 3k (Table 1, Entry 11)
Off-white
solid; yield 80%; mp 364 ˚C. ¹H
NMR (500 MHz, CDCl3): δ = 0.89 (t, J = 6.9 Hz,
3 H), 1.32 (m, 4 H), 1.47 (m, 2 H), 1.64 (m, 2 H), 2.82 (t, J = 8.4 Hz,
2 H), 5.87 (s, 1 H, D2O exchangeable), 6.33 (s, 1 H,
D2O exchangeable), 7.17 (d, J = 16.9
Hz, 1 H), 7.69 (d, J = 8.4
Hz, 2 H), 8.22 (d, J = 8.4
Hz, 2 H), 8.58 (d, J = 16.1
Hz. 1 H). ¹³C NMR (125 MHz, CDCl3): δ = 14.1,
22.5, 29.5, 30.3, 31.4, 33.8, 105.6, 117.8, 124.2, 124.2, 128.0,
128.7, 128.7, 137.1, 141.9, 148.2, 163.1, 166.0. IR (KBr): νmax = 3358,
3187, 2930, 2217, 1670, 1600, 1521, 1338 cm-¹.
ESI-MS: 328 [M + 1]. Anal. Calcd (%)
for C18H21N3O3: C, 66.04;
H, 6.47; N, 12.84. Found: C, 66.01; H, 6.43; N, 12.77.
<A NAME="RG15910ST-20">20</A>
Crystallographic data for compound 3a in this paper have been deposited with
the Cambridge Crystallographic Data Centre as supplemental publication
No. CCDC- 775677. Copies of the data can be obtained, free of charge
on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [fax: +44
(1223)336033 or email: deposit@ccdc.cam.ac.uk].