Synthesis and Characterization of Novel Oxo-TB Compounds

Oxo-TB 21a: ¹H NMR (500 MHz, DMSO-d₆, 25 °C): 8.78 (1H, ddt, 8.6, 1.3, 0.7, H9), 8.13 (1H, d, 8.9, H4), 7.91 (1H, br d, 8.2, H6), 7.87 (1H, br d, cov., H18), 7.86 (1H, br d, cov., H21), 7.81 (1H, d, 8.8, H16), 7.64 (1H, d, 8.9, H3), 7.64 (1H, ddd, 8.6, 7.0, 1.4, H8), 7.56 (1H, ddd, 8.5, 6.8, 1.3, H20), 7.52 (1H, d, 8.8, H15), 7.49 (1H, ddd, 8.1, 6.9, 1.2, H7), 7.48 (1H, ddd, 8.1, 6.9, 1.2, H19), 5.28 (1H, d, 17.3, H13 ^exo), 5.06 (1H, dd, 12.6, 1.5, H12a), 5.01 (1H, br d, 17.3, H13^endo), 4.98 (1H, d, 12.6, H12b). ¹³C{¹H} NMR (126 MHz, DMSO-d₆, 25 °C, from HSQC and HMBC): 173.83 (C11), 154.16 (C2), 140.41 (C14), 135.44 (C4), 131.87 (C10), 131.02 (C17), 130.88 (C5), 130.58 (C22), 128.51 (C6), 128.49 (C18), 128.27 (C8), 127.36 (C16), 126.75 (C20), 126.32 (C9), 125.58 (C19), 125.39 (C7), 124.86 (C15), 124.74 (C23), 122.89 (C3), 121.92 (C21), 115.07 (C1), 64.34 (C12), 51.36 (C13). HRMS (APCI⁺, MeOH): for C₂₃H₁₆N₂O calcd. [M + H]⁺ 337.1335 found 337.1339. HRMS (ESI⁺): for C₂₃H₁₆N₂O calcd. [M + H]⁺ 337.1335, too low intensity (<5%); calcd. for [M + Na]⁺ 359.1155 found 359.1157 (100%); calcd. [2M + Na]⁺ 695.2418, found 695.2417 (5%); calcd. [3M + Na]⁺ 1031.3680, found 1031.3695.
Dihydroquinazoline 7a: identified according to the characteristic singlet at 5.46 ppm (2H, s) having an HSQC correlation to the ¹³C signal at 45.28 ppm from the CH₂ group (an HMBC correlation to the ¹³C signal at 146.66 ppm), and the singlet at 8.09 ppm (1H, br s) having an HSQC correlation to the ¹³C signal at 146.66 ppm from the N=CH-N group. HRMS (APCI⁺, MeOH): for C₂₂H₁₆N₂ calcd. [M + H]⁺ 309.1386, found 309.1388.
Oxo-quinazoline 22a: ¹H NMR (500 MHz, DMSO-d₆, 25 °C): 9.83 (1H, ddt, 8.6, 1.3, 0.7, H9), 8.71 (1H, s, H12), 8.41 (1H, br d, 8.8, H4), 8.20 (1H, br d, 2.2, H13), 8.14 (1H, br d, 8.0, H6), 8.13 (1H, dq, 8.7, 0.7, H16), ~8.08 (1H, m, H18), ~8.05 (1H, m, H21), 7.83 (1H, d, 8.8, H3), 7.78 (1H, ddd, 8.6, 6.9, 1.6, H8), 7.74 (1H, dd, 8.7, 2.2, H15), 7.72 (1H, ddd, 8.0, 6.9, 1.3, H7), 7.68–7.63 (2H, m, H19 and H20). ¹³C{¹H} NMR (126 MHz, DMSO-d₆, 25 °C): 160.71 (C11), 150.26 (C2), 148.22 (C12), 136.05 (C4), 135.57 (C14), 132.94 (C22), 132.57 (C17), 131.79 (C5), 130.49 (C10), 128.75 (C6 or C8), 128.73 (C8 or C6), 128.70 (C16), 128.12 (C21), 127.76 (C18), 127.16 (C19), 126.91 (C20), 126.83 (C7), 126.43 (C9), 126.18 (C13), 126.15 (C3), 125.80 (C15), 115.12 (C1). HRMS (APCI⁺, MeOH): for C₂₂H₁₄N₂O calcd. [M + H]⁺ 323.1179, found 323.1172. HRMS (ESI⁺): for C₂₂H₁₄N₂O calcd. [M + H]⁺ 323.1179, found 323.1182 (70%); calcd. for [M + Na]⁺ 345.0998 found 345.1001 (93%); calcd. [2M + Na]⁺ 667.2105, found 667.2107 (100%); calcd. [3M + Na]⁺ 989.3211, found 989.3223 (23%).
SpiroTB 4a: ¹H NMR (500 MHz, DMSO-d₆, 25 °C): 7.85 (1H, m, H6), 7.77 (1H, d, 8.8, H4), 7.73 (1H, m, H9), 7.42 (1H, m, cov., H8), 7.41 (1H, m, cov., H7), 7.39 (1H, m, cov., H21), 7.36 (1H, m, cov., H20), 7.35 (1H, m, cov., H18), 7.34 (1H, m, cov., H3), 7.34 (1H, m, cov., H19), 7.02 (1H, d, 9.8, H16), 6.01 (1H, d, 9.8, H15), 5.09 (1H, d, 17.8, H13a), 4.89 (1H, d, 17.8, H13b), 3.85 (1H, br d, 12.6, H12a), 3.67 (1H, dd, 12.6, 1.8, H12b), 3.44 (1H, br d, 17.2, H11a), 2.93 (1H, d, 17.2, H11b). ¹³C{¹H} NMR (126 MHz, DMSO-d₆, 25 °C): 166.99 (C14), 144.54 (C2), 143.04 (C22), 133.89 (C16), 131.84 (C10), 131.65 (C17), 130.26 (C5), 129.00 (C20), 128.31 (C6), 128.12 (C18), 127.40 (C4), 127.31 (C19), 126.58 (C15), 126.55 (C8), 124.97 (C3), 124.73 (C21), 124.63 (C7), 122.74 (C1), 122.16 (C9), 73.33 (C13), 48.67 (C12), 38.76 (C11), 35.59 (C23). HRMS (APCI+, MeOH): for C₂₃H₁₈N₂ calcd. [M + H]⁺ 323.1543, found 323.1547. M.p. 84–86 °C decomp. (from methanol) did not match any of the bases isolated by Farrar [10 (link)].
Unidentified hydroxy-TB 23a: ¹H NMR (500 MHz, DMSO-d₆, 25 °C): 5.84 (1H, br d, 5.2, H11), 6.90 (d, 5.2, OH), 4.77 (1H, d, 12.4, 1.6, H12a), 4.40 (1H, d, 12.4, H12b), 4.96 (1H, d, 16.9, H13a), 4.70 (1H, br d, 16.9, H13b). ¹³C{¹H} NMR (126 MHz, DMSO-d₆, 25 °C): 82.83 (C11), 60.08 (C12), 54.25 (C13). HRMS (APCI⁺, MeOH): for C₂₃H₁₈N₂O calcd. [M + H]⁺ 339.1492, found 339.1494.

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Havlík M., Navrátilová T., Drozdová M., Tatar A., Lanza P.A., Dusso D., Moyano E.L., Chesta C.A., Vera D.M, & Dolenský B. (2023). Experimental, Spectroscopic, and Computational Insights into the Reactivity of “Methanal” with 2-Naphthylamines. Molecules, 28(4), 1549.

Publication 2023

13c nmr 1h nmr Dmso Methanol Quinazoline

Corresponding Organization : Fundación Ciencias Exactas y Naturales

Other organizations : Universidad Nacional de Córdoba, National University of Río Cuarto, Consejo Nacional de Investigaciones Científicas y Técnicas

Top 5 similar protocols

Variable analysis

independent variables

Oxo-TB 21a
Dihydroquinazoline 7a
Oxo-quinazoline 22a
SpiroTB 4a
Unidentified hydroxy-TB 23a

dependent variables

1H NMR (500 MHz, DMSO-d6, 25 °C)
13C{1H} NMR (126 MHz, DMSO-d6, 25 °C)
HRMS (APCI+, MeOH)
HRMS (ESI+)

control variables

DMSO-d6 solvent
Temperature at 25 °C

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