3.2. General Procedures for the Synthesis of N-Alkyl Amides 2a–k, 3a–k, and 4a–k

N-alkyl amides 2a–k, 3a–k, and 4a–k were synthesized using the method reported in the previous reference. The PyClOP (10 mmol) was added to a solution of carboxylic acid 1a–k (10 mmol), amine (butylamine, 2-methyl allylamine, or 1-amino-2-methyl propan-2-ol, 10 mmol), and DIEA (20 mmol) in 30 mL of dimethylformamide (DMF) at 0 °C. Next, the mixture solution was continuously stirred for 12 h at room temperature and then diluted with 20 mL water and 20 mL ethyl acetate. The organic layer was washed with 100 mL brine twice, 100 mL dilute HCl (1 mol/L) twice, 100 mL water twice, 100 mL 5% NaHCO₃ twice, and 100 mL brine twice. The resulting mixture solution was concentrated under vacuum and further purified by flash chromatography on a silica gel column (ethyl acetate: petroleum ether, 1:6) to afford the N-alkyl amides 2a–k, 3a–k, and 4a–k (yields 34–84%) as colorless oils, yellow oils, white solids, or yellow solids. ¹H NMR and ¹³C NMR spectrums of target compounds 2a–k, 3a–k, and 4a–k see the Supplementary Materials.

N-isobutylacetamide (2a). Yellow liquid; Yield 58%; ¹H NMR (300 MHz, CDCl₃): δ 5.73 (s, 1H, NH), 3.03–3.07 (m, 2H, CH₂), 1.97 (s, 3H, CH₃), 1.68–1.81 (m, 1H, CH), 0.89 (d, J = 6.0 Hz, 6H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 170.3, 46.9, 28.3, 23.1, 19.9, 19.7; HRMS calcd. for C₆H₁₃NO ([M + H]⁺), 116.1070; found, 116.1071.

N-isobutylacrylamide (2b). Yellow liquid; Yield 53%; ¹H NMR (300 MHz, CDCl₃): δ 6.89 (s, 1H, NH), 6.19 (d, J = 1.6 Hz, 1H, CH), 6.17 (s, 1H, CH), 5.52 (dd, J = 6.8, 5.2 Hz, 1H, CH), 3.05 (d, J = 13.0 Hz, 2H, CH₂), 1.74 (dp, J = 13.4, 6.7 Hz, 1H, CH), 0.84 (d, J = 6.7 Hz, 6H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 165.7, 131.0, 125.8, 46.9, 28.4, 20.0; HRMS calcd. for C₇H₁₃NO ([M + H]⁺), 128.1070; found, 128.1069.

N-isobutylpropionamide (2c). White liquid; Yield 34%; ¹H NMR (300 MHz, CDCl₃): δ 6.04 (s, 1H, NH), 3.00 (t, J = 6.4 Hz, 2H, CH₂), 2.16 (q, J = 7.6 Hz, 2H, CH₂), 1.71 (dq, J = 13.5, 6.7 Hz, 1H, CH), 1.09 (t, J = 7.6 Hz, 3H, CH₃), 0.84 (dd, J = 6.7 Hz, 6H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 172.7, 45.9, 28.4, 28.0, 19.9, 9.9; HRMS calcd. for C₇H₁₅NO ([M + H]⁺), 130.1226; found, 130.1225.

(E)-N-isobutylbut-2-enamide (2d). White solid; Mp 67.5–69.5 °C; Yield 51%; ¹H NMR (300 MHz, CDCl₃): δ 6.83 (dq, J = 15.1, 6.9 Hz, 1H, CH), 5.79 (dq, J = 15.2, 1.7 Hz, 1H, CH), 5.48 (s, 1H, NH), 3.14 (dd, J = 6.8, 6.1 Hz, 2H, CH₂), 1.84 (dd, J = 6.9, 1.7 Hz, 3H, CH₃), 1.76 (dt, J = 13.4, 6.7 Hz, 1H, CH), 0.91 (d, J = 6.7 Hz, 6H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 166.1, 139.2, 125.2, 46.7, 28.5, 20.0, 17.5; HRMS calcd. for C₈H₁₅NO ([M + H]⁺), 142.1226; found, 142.1225.

N-isobutylbutyramide (2e). White liquid; Yield 57%; ¹H NMR (300 MHz, CDCl₃): δ 5.78 (s, 1H, NH), 3.04–3.12 (m, 2H, CH₂), 2.17 (dd, J = 8.2, 6.8 Hz, 2H, CH₂), 1.61–1.81 (m, 3H, CH + CH₂), 0.88–0.98 (m, 9H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 171.7, 45.8, 37.3, 28.0, 19.9, 18.7, 13.4; HRMS calcd. for C₈H₁₇NO ([M + H]⁺), 144.1383; found, 144.1381.

(E)-N-isobutylpent-2-enamide (2f). Yellow solid; Mp 41.8–42.5 °C; Yield 72%; ¹H NMR (300 MHz, CDCl₃): δ 6.87 (m, J = 15.3, 6.4 Hz, 1H, CH), 5.82 (m, J = 1.7 Hz, 1H, CH), 5.77 (t, J = 1.7 Hz, 1H, NH), 3.14 (dd, J = 6.0, 6.1 Hz, 2H, CH₂), 2.19 (ddd, J = 7.5, 6.4, 1.7 Hz, 2H, CH₂), 1.72–1.90 (m, 1H, CH), 1.05 (t, J = 7.4 Hz, 3H, CH₃), 0.92 (d, J = 6.7 Hz, 6H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 166.3, 145.6, 122.8, 46.8, 28.5, 25.0, 20.1, 12.4; HRMS calcd. for C₉H₁₇NO ([M + H]⁺), 156.1383; found, 156.1382.

N-isobutylpentanamide (2g). White liquid; Yield 80%; ¹H NMR (300 MHz, CDCl₃): δ 5.73 (s, 1H, NH), 3.05–3.10 (m, 2H, CH₂), 2.16–2.21 (m, 2H, CH₂), 1.72–1.81 (m, 1H, CH), 1.57–1.67 (m, 2H, CH₂), 1.35 (dd, J = 15.0, 7.4 Hz, 2H, CH₂), 0.90–0.94 (m, 9H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 171.9, 45.8, 35.0, 28.0, 27.5, 21.7, 20.0, 13.6; HRMS calcd. for C₉H₁₉NO ([M + H]⁺), 158.1539; found, 158.1538.

(E)-N-isobutylhex-2-enamide (2h). White liquid; Yield 83%; ¹H NMR (300 MHz, CDCl₃): δ 6.79 (dt, J = 15.2, 7.0 Hz, 1H, CH₂), 5.94 (s, 1H, NH), 5.79 (dt, J = 15.3, 1.5 Hz, 1H, CH), 3.11 (dd, J = 6.8, 6.2 Hz, 2H, CH₂), 2.16–2.06 (m, 2H, CH₂), 1.76 (dq, J = 13.4, 6.7 Hz, 1H, CH₂), 1.44 (h, J = 7.3 Hz, 2H, CH₂), 0.95–0.80 (m, 9H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 166.2, 144.2, 123.8, 46.7, 34.0, 28.5, 21.4, 20.1, 13.6; HRMS calcd. for C₁₀H₁₉NO ([M + H]⁺), 170.1539; found, 170.1538.

(2E, 4E)-N-isobutylhexa-2, 4-dienamide (2i). White solid; Mp 106.5–107.0 °C; Yield 81%; ¹H NMR (300 MHz, CDCl₃): δ 7.18 (dd, J = 14.9, 9.9 Hz, 1H, CH), 6.01–6.19 (m, 2H, CH), 5.73 (d, J = 15.0 Hz, 1H, CH), 5.46 (s, 1H, NH), 3.14–3.18 (m, 2H, CH₂), 1.82–1.84 (m, 4H, CH + CH₃), 0.92 (d, J = 6.7 Hz, 6H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 166.5, 140.7, 137.2, 129.7, 121.9, 46.9, 28.5, 20.1, 18.4; HRMS calcd. for C₁₀H₁₇NO ([M + H]⁺), 168.1383; found, 168.1381.

N-isobutylhexanamide (2j). White liquid; Yield 84%; ¹H NMR (300 MHz, CDCl₃): δ 5.88 (s, 1H, NH), 3.07 (dd, J = 6.9, 6.0 Hz, 2H, CH₂), 2.16–2.21 (m, 2H, CH₂), 1.78 (dq, J = 13.4, 6.7 Hz, 1H, CH), 1.62–1.69 (m, 2H, CH₂), 1.26–1.35 (m, 4H, CH₂), 0.86–0.96 (m, 9H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 171.9, 45.8, 35.3, 30.8, 28.2, 28.0, 25.0, 21.8, 20.0, 13.8; HRMS calcd. for C₁₀H₂₁NO ([M + H]⁺), 172.1696; found, 172.1694.

N-isobutylheptanamide (2k). White liquid; Yield 63%; ¹H NMR (300 MHz, CDCl₃): δ 5.83 (s, 1H, NH), 3.06 (t, J = 6.4 Hz, 2H, CH₂), 2.13–2.22 (m, 2H, CH₂), 1.76 (tq, J = 13.4, 6.7 Hz, 1H, CH), 1.57–1.67 (m, 2H, CH₂), 1.28–1.33 (m, 6H, CH₂), 0.85–0.92 (m, 9H, CH₃); ¹³C NMR (75 MHz, DMSO-d₆) δ 171.9, 45.8, 35.3, 31.0, 28.3, 28.0, 25.3, 21.9, 20.0, 13.8; HRMS calcd. for C₁₁H₂₃NO ([M + H]⁺), 186.1852; found, 186.1842.

N-(2-hydroxy-2-methylpropyl)acetamide (3a). Colorless liquid; Yield 57%; ¹H NMR (300 MHz, CDCl₃): δ 6.29 (s, 1H, NH), 3.25 (d, J = 6.0 Hz, 2H, CH₂), 2.98 (s, 1H, OH), 2.03 (s, 3H, CH₃), 1.22 (s, 6H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 171.1, 70.7, 50.4, 27.1, 23.0; HRMS calcd. for C₆H₁₃NO₂ ([M + H]⁺), 132.1019; found, 132.1018.

N-(2-hydroxy-2-methylpropyl)acrylamide (3b). Colorless liquid; Mp 67.5–68.2 °C; Yield 54%; ¹H NMR (300 MHz, CDCl₃): δ 6.50 (s, 1H, NH), 6.12–6.33 (m, 2H, CH₂), 5.66 (dd, J = 9.9, 1.8 Hz, 1H, CH), 3.34 (d, J = 6.1 Hz, 2H, CH₂), 3.09 (s, 1H, OH), 1.23 (s, 6H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 166.6, 130.6, 126.7, 70.8, 50.4, 27.2; HRMS calcd. for C₇H₁₃NO₂ ([M + H]⁺), 144.1019; found, 144.1018.

N-(2-hydroxy-2-methylpropyl)propionamide (3c). Colorless liquid; Yield 61%; ¹H NMR (300 MHz, CDCl₃): δ 7.61 (s, 1H, NH), 4.44 (s, 1H, OH), 3.00 (d, J = 6.1 Hz, 2H, CH₂), 2.11 (q, J = 7.6 Hz, 2H, CH₂), 1.02 (s, 6H, CH₃), 0.98 (t, J = 7.6 Hz, 3H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 173.8, 70.0, 50.1, 29.0, 27.7, 10.7; HRMS calcd. for C₇H₁₅NO₂ ([M + H]⁺), 146.1176; found, 146.1173.

(E)-N-(2-hydroxy-2-methylpropyl)but-2-enamide (3d). Colorless liquid; Yield 47%; ¹H NMR (300 MHz, DMSO-d₆): δ 6.86 (dq, J = 15.2, 6.9 Hz, 1H, CH), 5.94 (s, 1H, NH), 5.81–5.88 (m, 1H, CH), 3.32 (d, J = 6.1 Hz, 2H, CH₂), 2.59 (s, 1H, OH), 1.86 (dd, J = 6.9, 1.7 Hz, 3H, CH₃), 1.23 (s, 6H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 167.1, 140.2, 124.8, 70.8, 50.4, 27.1, 17.6; HRMS calcd. for C₈H₁₅NO₂ ([M + H]⁺), 158.1176; found, 158.1175.

N-(2-hydroxy-2-methylpropyl)butyramide (3e). White solid; Mp 38.9–39.2 °C; Yield 56%; ¹H NMR (300 MHz, DMSO-d₆): δ 7.64 (s, 1H, NH), 4.44 (s, 1H, OH), 3.01 (d, J = 6.1 Hz, 2H, CH₂), 2.08 (t, J = 6.0 Hz, 2H, CH₂), 1.50 (h, J = 7.3 Hz, 2H, CH₂), 1.03 (s, 6H, CH₃), 0.84 (t, J = 7.4 Hz, 3H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 172.9, 100.0, 70.0, 50.1, 27.7, 19.3, 14.2; HRMS calcd. for C₈H₁₇NO₂ ([M + H]⁺), 160.1332; found, 160.1331.

(E)-N-(2-hydroxy-2-methylpropyl)pent-2-enamide (3f). Yellow liquid; Yield 61%; ¹H NMR (300 MHz, CDCl₃): δ 6.88–6.93 (m, 1H, CH), 6.09 (s, 1H, NH), 5.81 (d, J = 15.3 Hz, 1H, CH), 3.32 (d, J = 6.1 Hz, 2H, CH₂), 2.85 (s, 1H, OH), 2.18–2.23 (m, 2H, CH₂), 1.22 (s, 6H, CH₃), 1.05 (t, J = 7.4 Hz, 3H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 162.2, 141.3, 117.2, 65.5, 45.3, 21.9, 19.8, 7.1; HRMS calcd. for C₉H₁₇NO₂ ([M + H]⁺), 172.1332; found, 172.1330.

N-(2-hydroxy-2-methylpropyl)pentanamide (3g). White solid; Mp 64.2–65.2 °C; Yield 43%; ¹H NMR (300 MHz, DMSO-d₆): δ 7.64 (s, 1H, NH), 4.43 (s, 1H, OH), 3.01 (d, J = 6.0 Hz, 2H, CH₂), 2.11 (t, J = 7.4 Hz, 2H, CH₂), 1.47 (p, J = 7.4 Hz, 2H, CH₂), 1.22–1.29 (m, 2H, CH₂), 1.02 (s, 6H, CH₃), 0.85 (t, J = 7.4 Hz, 3H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 173.0, 70.0, 50.1, 35.6, 28.1, 27.7, 22.3, 14.3; HRMS calcd. for C₉H₁₉NO₂ ([M + H]⁺), 174.1489; found, 174.1487.

(E)-N-(2-hydroxy-2-methylpropyl)hex-2-enamide (3h). White solid; Mp 41.3–42.0 °C; Yield 43%; ¹H NMR (300 MHz, CDCl₃): δ 6.79–6.89 (dt, J = 15.3, 7.0 Hz, 1H, CH), 6.41 (s, 1H, NH), 5.82–5.88 (d, J = 15.3 Hz, 1H, CH), 3.33 (s, 2H, CH₂), 3.30 (s, 1H, OH), 2.15 (q, J = 7.3 Hz, 2H, CH₂), 1.40–1.52 (m, 2H, CH₂), 1.22 (s, 6H, CH₃), 0.90 (t, J = 7.4 Hz, 3H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 167.2, 145.0, 123.3, 70.8, 50.4, 34.0, 27.1, 21.4, 13.6; HRMS calcd. for C₁₀H₁₉NO₂ ([M + H]⁺), 186.1489; found, 186.1488.

(2E,4E)-N-(2-hydroxy-2-methylpropyl)hexa-2,4-dienamide (3i). White solid; Mp 142.2–142.7 °C; Yield 41%; ¹H NMR (300 MHz, CDCl₃): δ 7.20 (dd, J = 15.0, 9.8 Hz, 1H, CH), 6.03–6.20 (m, 3H, CH+NH), 5.77 (d, J = 15.0 Hz, 1H, CH), 3.34 (d, J = 6.1 Hz, 2H, CH₂), 2.82 (s, 1H, OH), 1.83 (d, J = 5.7 Hz, 3H, CH₃), 1.23 (s, 6H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 167.6, 141.5, 138.0, 129.6, 121.2, 70.8, 50.5, 27.1, 18.5; HRMS calcd. for C₁₀H₁₇NO₂ ([M + H]⁺), 184.1332; found, 184.1331.

N-(2-hydroxy-2-methylpropyl)hexanamide (3j). White solid; Mp 53.8–54.3 °C; Yield 52%; ¹H NMR (300 MHz, DMSO-d₆): δ 7.64 (m, 1H, NH), 4.43 (s, 1H, OH), 3.00 (d, J = 6.1 Hz, 2H, CH₂), 2.10 (t, J = 7.4 Hz, 2H, CH₂), 1.49 (p, J = 7.4 Hz, 2H, CH₂), 1.18–1.29 (m, 4H, CH₂), 1.02 (s, 6H, CH₃), 0.85 (t, J = 7.1 Hz, 3H, CH₃); ¹³C NMR (75 MHz, DMSO-d₆): δ 173.0, 70.0, 50.1, 35.8, 31.4, 27.7, 25.6, 22.4, 14.4; HRMS calcd. for C₁₀H₂₁NO₂ ([M + H]⁺), 188.1645; found, 188.1643.

N-(2-hydroxy-2-methylpropyl)heptanamide (3k). White liquid; Yield 43%; ¹H NMR (300 MHz, DMSO-d₆): δ 7.64 (s, 1H, NH), 4.43 (s, 1H, OH), 3.37 (s, 2H, CH₂), 3.00 (d, J = 6.1 Hz, 2H, CH₂), 2.10 (t, J = 6.0 Hz, 2H, CH₂), 1.49 (p, J = 7.4 Hz, 2H, CH₂), 1.24 (dqd, J = 22.7, 7.9, 7.4, 2.0 Hz, 4H, CH₂), 1.02 (s, 6H, CH₃), 0.84 (t, J = 7.1 Hz, 3H, CH₃); ¹³C NMR (75 MHz, DMSO-d₆): δ 173.0, 70.0, 50.1, 35.8, 31.4, 27.7, 25.6, 22.4, 14.4; HRMS calcd. for C₁₁H₂₃NO₂ ([M + H]⁺), 202.1802; found, 202.1800.

N-(2-methylallyl)acetamide (4a). Yellow liquid; Yield 56%; ¹H NMR (300 MHz, CDCl₃): δ 5.80 (s, 1H, NH), 4.82–4.84 (s, 2H, CH₂), 3.80 (d, J = 6.0 Hz, 2H, CH₂), 2.02 (s, 3H, CH₃), 1.73 (m, 3H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 170.2, 141.7, 110.4, 44.8, 22.8, 20.1; HRMS calcd. for C₆H₁₁NO ([M+H]⁺), 114.0913; found, 114.0915.

N-(2-methylallyl)acrylamide (4b). White liquid; Yield 64%; ¹H NMR (300 MHz, CDCl₃): δ 6.31 (dd, J = 17.0, 1.7 Hz, 1H, CH), 6.15 (dd, J = 17.0, 10.1 Hz, 1H, CH₂), 5.94 (s, 1H, NH), 5.66 (dd, J = 10.0, 1.7 Hz, 1H, CH), 4.85 (h, J = 1.1 Hz, 2H, CH₂), 3.89 (d, J = 6.1 Hz, 2H, CH₂), 1.75 (s, 3H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 165.8, 141.6, 130.9, 126.1, 110.9, 45.0, 20.3; HRMS calcd. for C₇H₁₁NO ([M + H]⁺), 126.0913; found, 126.0912.

N-(2-methylallyl)propionamide (4c). Yellow liquid; Yield 69%; ¹H NMR (300 MHz, CDCl₃): δ 5.57 (s, 1H, NH), 4.81–4.83 (s. 2H, CH), 3.91 (d, J = 6.0 Hz, 2H, CH₂), 2.24 (q, J = 7.6 Hz, 2H, CH₂), 1.73 (s, 3H, CH₃), 1.18 (t, J = 7.6 Hz, 3H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 165.8, 141.6, 130.9, 126.1, 110.9, 45.0, 20.2; HRMS calcd. for C₇H₁₃NO ([M + H]⁺), 128.1070; found, 128.1070.

(E)-N-(2-methylallyl)but-2-enamide (4d). Yellow liquid; Yield 59%; ¹H NMR (300 MHz, CDCl₃): δ 6.87 (dq, J = 15.1, 6.9 Hz, 1H, CH), 5.84 (dq, J = 15.2, 1.7 Hz, 1H, CH), 5.62 (s, 1H, NH), 4.84 (p, J = 1.2 Hz, 2H, CH₂), 3.88 (d, J = 6.1 Hz, 2H, CH₂), 1.87 (dd, J = 6.9, 1.7 Hz, 3H, CH₃), 1.75 (d, J = 1.1 Hz, 3H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 166.0, 141.9, 139.7, 124.9, 110.7, 44.8, 20.2, 17.6; HRMS calcd. for C₈H₁₃NO ([M + H]⁺), 140.1070; found, 140.1068.

N-(2-methylallyl)butyramide (4e). Colorless liquid; Yield 54%; ¹H NMR (300 MHz, CDCl₃): δ 6.85–6.93 (m, 1H, CH), 5.79 (dt, J = 15.3, 1.7 Hz, 1H, CH), 5.62 (s, 1H, NH), 4.83 (p, J = 1.1 Hz, 2H, CH₂), 3.88 (d, J = 6.1 Hz, 2H, CH₂), 2.21 (ddd, J = 7.7, 6.4, 1.5 Hz, 2H, CH₂), 1.74 (s, 3H, CH₃), 1.06 (s, 3H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 172.9, 141.9, 110.4, 44.7, 38.3, 20.2, 19.1, 13.6; HRMS calcd. for C₈H₁₅NO ([M + H]⁺), 142.1226; found, 142.1225.

(E)-N-(2-methylallyl)pent-2-enamide (4f). Colorless liquid; Yield 53%; ¹H NMR (300 MHz, CDCl₃): δ 6.85–69.5 (m, 1H, CH), 5.62–5.82 (dt, J = 15.3, 1.7 Hz, 1H, CH), 5.62 (s, 1H, NH), 4.83 (q, J = 1.1 Hz, 2H, CH₂), 3.88 (d, J = 6.1 Hz, 2H, CH₂), 2.21 (ddd, J = 7.7, 6.4, 1.5 Hz, 2H, CH₂), 1.04 (s, 3H, CH₃), 1.06 (t, J = 7.4 Hz, 3H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 166.2, 146.0, 141.9, 122.6, 110.7, 44.9, 25.0, 20.3, 12.4; HRMS calcd. for C₉H₁₅NO ([M + H]⁺), 154.1226; found, 154.1224.

N-(2-methylallyl)pentanamide (4g). Yellow liquid; Yield 61%; ¹H NMR (300 MHz, CDCl₃): δ 5.85 (s, 1H, NH), 4.92–4.78 (m, 2H, CH₂), 3.81 (d, J = 6.0 Hz, 2H, CH₂), 2.19–2.28 (m, 2H, CH₂), 1.74 (d, J = 2.9 Hz, 3H, CH₃), 1.57–1.70 (m, 2H, CH₂), 1.30–1.44 (m, 2H, CH₂), 0.93 (t, J = 7.3 Hz, 3H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 173.2, 141.9, 110.3, 44.6, 36.2, 27.8, 22.2, 20.1, 13.6; HRMS calcd. for C₉H₁₇NO ([M + H]⁺), 156.1383; found, 156.1381.

(E)-N-(2-methylallyl)hex-2-enamide (4h). White solid; Mp 37.0–38.8 °C; Yield 57%; ¹H NMR (300 MHz, CDCl₃): δ 6.85 (dt, 1H, J = 15.3, 7.0 Hz, CH), 5.80 (dt, 1H, J = 15.3, 1.5 Hz, CH), 5.66 (s, 1H, NH), 4.83 (q, J = 1.2 Hz, 2H, CH₂), 3.87 (d, J = 6.1 Hz, 2H, CH₂), 2.15 (qd, J = 7.1, 1.5 Hz, 2H, CH₂), 1.73–1.75 (m, 3H, CH₃), 1.47 (h, J = 7.3 Hz, 2H, CH₂), 0.92 (t, J = 7.4 Hz, 3H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 166.0, 144.7, 142.0, 123.5, 110.8, 44.9, 34.0, 21.4, 20.3, 13.6; HRMS calcd. for C₁₀H₁₇NO ([M + H]⁺), 168.1383; found, 168.1381.

(2E, 4E)-N-(2-methylallyl)hexa-2,4-dienamide (4i). Yellow solid; Mp 66.3–67.1 °C; Yield 49%; ¹H NMR (300 MHz, CDCl₃): δ 7.17–7.25 (m, 1H, CH), 6.03–6.21 (m, 2H, CH), 5.77 (d, J = 14.9 Hz, 1H, CH), 5.58 (s, 1H, NH), 4.84 (q, J = 1.2 Hz, 2H, CH₂), 3.89 (d, J = 6.1 Hz, 2H, CH₂), 1.83 (d, J = 5.8 Hz, 3H, CH₃), 1.75 (s, 3H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 166.5, 141.9, 141.2, 137.6, 129.6, 121.4, 110.8, 45.0, 20.3, 18.4; HRMS calcd. for C₁₀H₁₅NO ([M + H]⁺), 166.1226; found, 166.1225.

N-(2-methylallyl)hexanamide (4j). Yellow liquid; Yield 61%; ¹H NMR (300 MHz, CDCl₃): δ 5.72 (s, 1H, NH), 4.84 (dt, J = 2.6, 1.3 Hz, 2H, CH₂), 3.82 (dd, J = 6.0, 1.4 Hz, 2H, CH₂), 2.20–2.25 (m, 2H, CH₂), 1.74–1.75 (m, 3H, CH₃), 1.62–1.69 (m, 2H, CH₂), 1.29–1.38 (m, 4H, CH₂), 0.89–0.93 (m, 3H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 173.1, 141.9, 110.4, 44.7, 36.4, 31.3, 25.4, 22.2, 20.1, 13.7; HRMS calcd. for C₁₀H₁₉NO ([M + H]⁺), 170.1539; found, 170.1538.

N-(2-methylallyl)heptanamide (4k). Colorless liquid; Yield 67%; ¹H NMR (300 MHz, CDCl₃): δ 5.87 (s, 1H, NH), 4.82 (p, J = 1.4 Hz, 2H, CH₂), 3.81 (d, J = 6.0 Hz, 2H, CH₂), 2.19–2.24 (m, 2H, CH₂), 1.73 (s, 3H, CH₃), 1.62–1.67 (m, 2H, CH₂), 1.26–1.35 (m, 6H, CH₂), 0.86–0.90 (m, 3H, CH₃); ¹³C NMR (75 MHz, CDCl₃): δ 173.2, 141.9, 110.3, 77.4, 77.0, 76.6, 44.6, 36.4, 31.4, 28.8, 25.7, 22.3, 20.1, 13.8; HRMS calcd. for C₁₁H₂₁NO ([M + H]⁺), 184.1696; found, 184.1694.