“…A solution containing 200 mg of 4,7-dimethyl-3-methoxychromene (25) in 175 mL of methanol was irradiated with a 550-W Hanovia lamp equipped with a Pyrex filter for 1 h. Removal of the solvent under reduced pressure followed by purification of the residual oil by thick layer chromatography using a 10% acetone-hexane mixture as the eluent gave 185 mg (79%) of 2,3-dimethoxy-3-( ,=Z = 3.0 Hz), 5.68 (d, 1 ,=/ = 3.0 Hz), 3.5-3.1 (m, 3 H), and 1.77 (s, 1 H, exchangeable with D20); UV (methanol) 281 (shoulder) and 276 nm (c 2620 and 2690); m/e 222 (M+), 207,190,175,159 (base), 147,133,115,105,91, and 77. In addition to the signals described above, the crude photolysate contained peaks at 7.75 (s), 6.41 (s), 5.6-6.0 (m), 4.89 (m), 4.18 (m), 3.1-3.5 (m, 3 H), and 1.68 (s, 1 H, exchanged with D20) which were assigned to 2-methoxy-3-(2-hydroxy-4-methylphenyl)-l,3-butadiene (27).…”