“…Compound 8 1 H NMR (CDCl3, 400 MHz) δ 10.5 (brs, 1H), 7.84 (dd, J = 3.6, 0.8 Hz, 1H), 7.58 (dd, J = 5.2, 0.8 Hz, 1H), 7.09(dd, J = 5.2, 3.6 Hz, 1H). Synthesis of (Hydroxy(thiophen-2-yl)methyl)diphenylphosphine Oxide (5I)[30] A 50 mL round-bottom flask containing a magnetic stirring bar were added thiophene-2-carbaldehyde (5B: 449 mg, 4.0 mmol, 1.0 equiv) and diphenylphosphine oxide (2A: 809 mg, 4.0 mmol, 1.0 equiv). After stirring the mixture for 4 h at room temperature, the mixture was filtrated.…”