2-Hydroxy-4-Methoxybenzaldehyde → 6a, 11a-Dihydro-3,9-dimethoxy-6-H-[1]benzothieno[3,2-c][1]benzopyran-6-one

Participants

Reaction Steps

To a stirred solution of 6-methoxythianaphthen-2-one (see Docket B-9459) (20 g, 111 mmol) in a mixture of ethanol (100 mL) and methylene chloride (50 mL) was added 4-methoxysalicylaldehyde (17.5 g, 115 mmol) followed by triethylamine (567 mg, 784 mL, 5.6 mmol) at room temperature. After 30 min, a solid began to precipitate and stirring was continued overnight. The mixture was then diluted with cold hexane (1 L) and filtered to yield 28.7 g (82%) of the title product as an off-white solid, pure by 1H-NMR analysis. An analytical sample was obtained by recrystallization from toluene as light yellow crystals, mp 157-165d° C.: 1H-NMR (300 MHz, CDCl3) d 7.33 (d, J=8.6 Hz, 1H), 7.31 (d, J=8.1 Hz, 1H), 6.75 (d, J=2.4 Hz, 1H), 6.70 (m, 2H), 6.60 (d, J=2.5 Hz, 1H), 5.22 (d, J=7.2 Hz, 1H), 4.33 (d, J=7.2 Hz, 1H), 3.79 (s, 3H), 3.76 (s, 3H); IR (CHCl3) 1759 cm-1 ; MS (FD) m/e 314 (M+); Anal. calc'd. for C17H14O4S: C, 64.95; H, 4.50. Found: C, 65.01; H, 4.58.

Provenance & Evidence