First Vilsmeier-Haack Synthesis of Flavones using bis-(Trichloromethyl) Carbonate/Dimethylformamide

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Acknowledgment

We are grateful to the Natural Science Foundation of Zhejiang province (No. 202095) and the Natural Science Foundation of China (No. 20676123) for financial help.

Notes

^aSubstrate 1 (2 mmol), BTC (1.33 mmol) and DMF (4 mL, 4 mmol) was used.

^bIsolated yields.

^c13C NMR (CDCl₃): δ 177.89, 161.60, 156.05, 145.11, 137.55, 130.11, 129.14, 127.24, 126.66, 125.25, 121.46, 117.63, 107.36, 21.69; IR (KBr): 1638, 1490, 1410, 1092, 906, 827, 813, 477 cm⁻¹; MS (EI): m/z (%) = 270 (5) [M⁺], 242 (100), 178 (90), 152 (70), 78 (6); Anal. Calcd for C₁₆H₁₁ClO₂: C, 70.99; H, 4.10; Found: C, 70.92; H, 4.04.