. 2010 Dec 30;9(1):71–81. doi: 10.3390/md9010071

Table 2.

Spectral data for 1–4.

Compound	IR (CHCl₃/KBr, v cm⁻¹), ¹H/¹³C NMR (CDCl₃, δ ppm), ESIMS/MS (rel. int., m/z)
1	3128, 3123 (N–H str, amide), 2998–2989 (C–H str, CH₂, Pro), 2966, 2928 (C–H str, asym, CH₃ and CH₂), 1748 (C=O str, ester), 1675, 1643 (C=O str, tert and sec amide), 1539 (N–H def, sec amide), 1391, 1377 (C–H def, tert-Butyl), 1384, 1369 (C–H def, iso-propyl), 1267 (C–O str, ester) 6.65 (1H, br. s, NH), 4.40 (1H, q, H-α, Leu), 4.05 (1H, t, J = 7.2 Hz, H-α, Pro), 3.62 (3H, s, OCH₃), 3.22 (2H, t, J = 7.2 Hz, H-δ, Pro), 2.58 (2H, q, H-β, Pro), 1.96–1.88 (2H, m, H-γ, Pro), 1.47 (9H, s, tert-Butyl), 1.45–1.36 (3H, m, H-β and H-γ, Leu), 0.94 (6H, d, J = 6.35 Hz, H-δ, Leu)
1a	3297–2478 (m/br, OH str, COOH), 3125, 3122 (N–H str, amide), 2999–2992 (C–H str, CH₂, Pro), 2968, 2929 (C–H str, asym, CH₃ and CH₂), 1711 (s, C=O str, COOH), 1678, 1642 (C=O str, tert and sec amide), 1536 (N–H def, sec amide), 1393, 1375 (C–H def, tert-Butyl), 1385, 1368 (C–H def, iso-propyl) 12.52 (1H, s, OH, COOH), 6.73 (1H, br. s, NH), 4.47 (1H, q, H-α, Leu), 3.86 (1H, t, J = 7.2 Hz, H-α, Pro), 3.21 (2H, t, J = 7.15 Hz, H-δ, Pro), 2.55 (2H, q, H-β, Pro), 1.95–1.87 (3H, m, H-γ, Pro and Leu), 1.56 (2H, t, H-β, Leu), 1.49 (9H, s, tert-Butyl), 0.95 (6H, d, J = 6.4 Hz, H-δ, Leu)
2	3502, 3396 (N–H str, sec amine), 3132, 3127 (N–H str, amide), 2965, 2928 (C–H str, asym, CH₃ and CH₂), 2874 (C–H str, sym, CH₃), 1747 (C=O str, ester), 1646 (C=O str, sec amide), 1535 (N–H def, sec amide), 1269 (C–O str, ester), 1159 (C–N str, sec amine) 5.89 (1H, br. s, NH), 4.28 (1H, t, J = 6.4 Hz, H-α, Ile), 3.75–3.69 (1H, m, H-α, Ala), 3.51 (3H, s, OCH₃), 2.03–1.95 (1H, m, H-β, Ile), 1.70–1.62 (2H, m, H-γ, Ile), 1.46 (2H, br. s, NH₂), 1.15 (3H, d, J = 7.25 Hz, H-β, Ala), 0.94 (3H, t, J = 7.2 Hz, H-δ, Ile), 0.86 (3H, d, J = 6.4 Hz, H-γ′, Ile)
3	3129–3122 (N–H str, amide), 2999–2993 (C–H str, CH₂, Pro), 2968, 2929, 2925 (C–H str, asym, CH₃ and CH₂), 2878–2873 (C–H str, sym, CH₃), 1745 (C=O str, ester), 1676, 1646–1641 (C=O str, tert and sec amide), 1538, 1535 (N–H def, sec amide), 1392, 1375 (C–H def, tert-Butyl), 1386, 1368 (C–H def, iso-propyl), 1272 (C–O str, ester) 8.48 (1H, br. s, NH), 7.45 (1H, br. s, NH), 5.14 (1H, br. s, NH), 4.52 (1H, q, H-α, Leu), 4.25 (1H, q, H-α, Ala), 4.14 (1H, t, J = 7.2 Hz, H-α, Pro), 3.73 (1H, t, J = 6.35 Hz, H-α, Ile), 3.49 (3H, s, OCH₃), 3.43 (2H, t, J = 7.25 Hz, H-δ, Pro), 2.49 (2H, q, H-β, Pro), 2.05–1.97 (1H, m, H-β, Ile), 1.95–1.89 (2H, m, H-γ, Pro), 1.83–1.62 (4H, m, H-β, Leu and H-γ, Ile), 1.48 (9H, s, tert-Butyl), 1.48–1.43 (1H, m, H-γ, Leu), 1.29 (3H, d, J = 7.2 Hz, H-β, Ala), 0.99 (6H, d, J = 6.4 Hz, H-δ, Leu), 0.93 (3H, t, J = 7.15 Hz, H-δ, Ile), 0.89 (3H, d, J = 6.45 Hz, H-γ′, Ile) 174.8 (C=O, Leu), 172.9, 172.4 (2C, C=O, Pro and Ile), 169.8 (C=O, Ala), 156.2 (C=O, Boc), 79.8 (C-α, tert-Butyl), 59.7 (C-α, Pro), 58.5 (C-α, Ile), 54.7 (OCH₃), 51.3 (C-α, Ala), 49.7 (C-α, Leu), 46.9 (C-δ, Pro), 37.6, 37.1 (2C, C-β, Ile and Leu), 28.9 (C-β, Pro), 28.2 (3C, C-β, tert-Butyl), 24.2, 23.9 (2C, C-γ, Ile and Leu), 23.7 (C-γ, Pro), 22.3 (2C, C-δ, Leu), 17.9 (C-β, Ala), 15.1 (C-γ′, Ile), 9.5 (C-δ, Ile)
4	3128, 3123, 3119 (N–H str, amide), 2998, 2995–2992 (C–H str, CH₂, Pro), 2969, 2928–2924 (C–H str, asym, CH₃ and CH₂), 2879, 2875 (C–H str, sym, CH₃), 1675, 1648–1643 (C=O str, tert and sec amide), 1539–1536 (N–H def, sec amide), 1385, 1369 (C–H def, iso-propyl) 9.37 (1H, br. s, NH), 9.31 (1H, br. s, NH), 7.76 (1H, br. s, NH), 4.26 (1H, t, J = 7.15 Hz, H-α, Pro), 3.99 (1H, q, H-α, Ala), 3.95 (1H, q, H-α, Leu), 3.61 (1H, t, J = 6.4 Hz, H-α, Ile), 3.52 (2H, t, J = 7.3 Hz, H-δ, Pro), 2.35 (2H, q, H-β, Pro), 1.96–1.83 (2H, m, H-γ, Pro), 1.89–1.83 (1H, m, H-γ, Leu), 1.81–1.76 (1H, m, H-β, Ile), 1.73–1.64 (2H, m, H-β, Leu), 1.59–1.53 (2H, m, H-γ, Ile), 1.45 (3H, d, J = 7.25 Hz, H-β, Ala), 0.98 (6H, d, J = 6.35 Hz, H-δ, Leu), 0.95 (3H, d, J = 6.45 Hz, H-γ′, Ile), 0.89 (3H, t, J = 7.2 Hz, H-δ, Ile) 171.1 (C=O, Leu), 170.9 (C=O, Ala), 170.5, 168.1 (2C, C=O, Pro and Ile), 63.3 (C-α, Ile), 57.5 (C-α, Pro), 54.1 (C-α, Leu), 49.9 (C-α, Ala), 46.5 (C-δ, Pro), 43.8, 39.9 (2C, C-β, Leu and Ile), 29.9 (C-β, Pro), 24.8, 24.2 (2C, C-γ, Ile and Leu), 22.0 (2C, C-δ, Leu), 21.3 (C-γ, Pro), 19.2 (C-β, Ala), 15.4 (C-γ′, Ile), 9.8 (C-δ, Ile) 395.4 [(M + H)⁺, 100], 367.4 [(395.4 − CO)⁺, 11], 324.4 [(H-Ile-Pro-Leu)⁺, 32], 298.4 [(H-Leu-Ala-Ile)⁺, 39], 296.4 [(324.4 − CO)⁺, 10], 282.3 [(H-Ala-Ile-Pro)⁺, 29], 270.3 [(298.4 − CO)⁺, 17], 254.3 [(282.3 − CO)⁺, 15], 211.3 [(H-Ile-Pro)⁺, 19], 185.2 [(H-Leu-Ala)⁺, 76], 157.2 [(185.2 − CO)⁺, 12], 114.1 [(H-Leu)⁺, 19], 86.1 [Ile/Leu (C₅H₁₂N)⁺, 16], 70.1 [Pro (C₄H₈N)⁺, 10], 57.1 [(C₄H₉)⁺, 15], 44.1 [Ala (C₂H₆N)⁺, 12], 43.1 [(C₃H₇)⁺, 11], 29.1 [(C₂H₅)⁺, 9], 15.0 [(CH₃)⁺, 13]