# Aromatic Amines in Organic Synthesis Part III; \(p\)-Aminocinnamic Acids and Their Methyl Esters
## 3 Materials and Methods
### Synthesis
#### 3.1.2 Synthesis of the Methyl \(p\)-(Dimethylamino)cinnamate
_3-[4-(Dimethylamino)-2-methylphenyl]acrylic acid (2d)_  
The compound was obtained as a pale-yellow solid; yield: 63%; mp 176 \({}^{\circ}\)C.  
\({}^{1}\)H NMR (400 MHz, DMSO-\(d_{6}\)) \(\sigma\) (ppm): 12.00 (s, 1H, COOH), 7.71 (d, \(J\) = 15.8 Hz, 1H, -CH=), 7.56 (d, \(J\) = 8.6 Hz, 1H), 6.59-6.54 (m, 3H), 6.18 (d, \(J\) = 15.7 Hz, 1H, -CH=), 2.95 (s, 6H, N(CH\({}_{3}\))\({}_{2}\)), 2.34 (s, 3H, ArCH\({}_{3}\)). \({}^{13}\)C NMR (100 MHz, DMSO-\(d_{6}\)) \(\sigma\) (ppm): 168.8 (CHO), 151.8 (C), 141.7 (CH), 139.1 (C), 128.2 (CH), 120.7 (C), 114.3 (CH), 113.7 (CH), 110.6 (CH), 40.1 (N(CH\({}_{3}\))\({}_{2}\)), 20.3 (ArCH\({}_{3}\)). IR (KBr): 1680, 1586, 1514, 1366, 1290, 1099, 827. Anal. Calcd for C\({}_{12}\)H\({}_{15}\)NO\({}_{2}\): C, 70.23; H, 7.37; N, 6.83. Found: C, 70.15; H, 7.27; N, 6.79. _3-[4-(Dimethylamino)-2,6-dimethylphenyl]acrylic acid (2e)_  
The compound was obtained as a pale-yellow solid; yield: 29%; mp 176 \({}^{\circ}\)C.  
\({}^{1}\)H NMR (400 MHz, DMSO-\(d_{6}\)) \(\sigma\) (ppm): 12.12 (s, 1H, COOH), 7.75 (d, \(J\) = 16.2 Hz, 1H, -CH=), 6.47 (s, 1H), 5.93 (d, \(J\) = 16.2 Hz, 1H, -CH=), 2.93 (s, 6H, N(CH\({}_{3}\))\({}_{2}\)), 2.32 (s, 6H, ArCH\({}_{3}\)). \({}^{13}\)C NMR (100 MHz, DMSO-\(d_{6}\)) \(\sigma\) (ppm): 168.7 (COOH), 150.6 (C), 142.3 (CH), 139.2 (C), 120.8 (C), 119.3 (CH), 112.7 (CH), 40.1 (N(CH\({}_{3}\))\({}_{2}\)), 22.5 (ArCH\({}_{3}\)). IR (KBr): 1672, 1581, 1364, 1313, 1219, 1201, 1144, 822. Anal. Calcd for C\({}_{13}\)H\({}_{17}\)NO\({}_{2}\): C, 71.21; H, 7.82; N, 6.39. Found: C, 71.25; H, 7.78; N, 6.45. _3-[4-(Dimethylamino)-3-methylphenyl]acrylic acid (2f)_  
The compound was obtained as a light-gray solid; yield: 69%; mp 129 \({}^{\circ}\)C.  
\({}^{1}\)H NMR (400 MHz, DMSO-\(d_{6}\)) \(\sigma\) (ppm): 12.21 (s, 1H, COOH), 7.51-7.44 (m, 3H), 7.04 (d, \(J\) = 5.1 Hz, 1H), 6.37 (d, \(J\) = 15.9 Hz, 1H, -CH=), 2.72 (s, 6H, N(CH\({}_{3}\))\({}_{2}\)), 2.29 (s, 3H, ArCH\({}_{3}\)). The compound was obtained as a pale-yellow solid; yield: 63%; mp 176 \({}^{\circ}\)C.  
\({}^{1}\)H NMR (400 MHz, DMSO-\(d_{6}\)) \(\sigma\) (ppm): 12.00 (s, 1H, COOH), 7.71 (d, \(J\) = 15.8 Hz, 1H, -CH=), 7.56 (d, \(J\) = 8.6 Hz, 1H), 6.59-6.54 (m, 3H), 6.18 (d, \(J\) = 15.7 Hz, 1H, -CH=), 2.95 (s, 6H, N(CH\({}_{3}\))\({}_{2}\)), 2. \({}^{13}\)C NMR (100 MHz, DMSO-\(d_{6}\)) \(\sigma\) (ppm): 168.3 (COOH), 154.5 (C), 144.4 (CH), 131.4 (CH), 131.3 (C), 128.3 (C), 127.5 (CH), 118.7 (CH), 117.0 (CH), 43.9 (N(CH\({}_{3}\))\({}_{2}\)), 19.0 (ArCH\({}_{3}\)). IR (KBr): 1684, 1621, 1602, 1506, 1420, 1279, 1232, 1109, 982, 827. Anal. Calcd for C\({}_{12}\)H\({}_{15}\)NO\({}_{2}\): C, 70.23; H, 7.37; N, 6.83. Found: C, 70.15; H, 7.31; N, 6.81. \({}^{3}\)_[4-(Dimethylamino)-2,5-dimethylphenyl)acrylic acid (2g)_  
The compound was obtained as a brown solid; yield: 61%; mp 151 \({}^{\circ}\)C.  
\({}^{1}\)H NMR (400 MHz, DMSO-\(d_{6}\)) \(\sigma\) (ppm): 12.21 (s, 1H, COOH), 7.73 (d, \(J\) = 15.8 Hz, 1H, -CH=), 7.50 (s, 1H), 6.82 (s, 1H), 6.28 (d, \(J\) = 15.8 Hz, 1H, -CH=), 2.67 (s, 6H, N(CH\({}_{3}\))\({}_{2}\)), 2.33 (s, 3H, ArCH\({}_{3}\)), 2.23 (s, 3H, ArCH\({}_{3}\)). \({}^{13}\)C NMR (100 MHz, DMSO-\(d_{6}\)) \(\sigma\) (ppm): 168.3 (COOH), 154.6 (C), 141.5 (CH), 136.2 (C), 129.7 (CH), 128.8 (C), 126.3 (C), 120.2 (CH), 117.4 (CH), 43.7 (N(CH\({}_{3}\))\({}_{2}\)), 19.5 (CH\({}_{3}\)), 18.7 (CH\({}_{3}\)). IR (KBr): 1682, 1599, 1508, 1318, 1236, 1211, 1075, 984, 859. Anal. Calcd for C\({}_{13}\)H\({}_{17}\)NO\({}_{2}\): C, 71.21; H, 7.82; N, 6.39. Found: C, 71.14; H, 7.73; N, 6.30. 3-[4-(Pyrrolidin-1-yl)phenyl)acrylic acid (2h)  
The compound was obtained as a light-brown solid; yield: 73%; mp 261 \({}^{\circ}\)C.  
\({}^{1}\)H NMR (400 MHz, DMSO-\(d_{6}\)) \(\sigma\) (ppm): 11.90 (s, 1H, COOH), 7.49 \(-\) 7.45 (m, 3H), 6.53 (d, \(J\) = 8.8 Hz, 2H), 6.18 (d, \(J\) = 15.8 Hz, 1H, -CH=), 3.28 (t, \(J\) = 5.0 Hz, 4H, NCH\({}_{2}\)), 1.95 (m, 4H, CH\({}_{2}\)).