“…4‐Benzylthio‐1,2‐butadiene (2t): The reaction of CuI (190.9 mg, 1.00 mmol), paraformaldehyde (481.3 mg, 16.03 mmol), 1t (1.6255 g, 1.00 mmol), and i Pr 2 NH (2.0 mL, d = 0.716 g mL –1 , 1.432 g, 14.15 mmol) in dioxane (15 mL) afforded 2t 11j (1.4032 g, 79 %) after purification (eluent for chromatography: petroleum ether) as a liquid. 1 H NMR (300 MHz, CDCl 3 ): δ = 7.34–7.17 (m, 5 H, ArH), 5.16 (quint, J = 7.1 Hz, 1 H, C=CH), 4.85–4.76 (dd, J = 6.2, 2.0 Hz, 2 H, C=CH 2 ), 3.72 (s, 2 H, ArCH 2 ), 3.07–2.96 (m, 2 H, SCH 2 ) ppm.…”