Reaction Steps
A solution of 0.70 g (2.90 mmol) of 2 and 1.00 g (7.20 mmol) of 6 in 10 mL of toluene in a sealed tube was heated at 150° C. for 1 day, cooled to 25° C., concentrated to dryness, and column chromatographed on silica gel using a gradient mixture of hexane and ethyl acetate as solvent gave 0.52 g (48% yield) of compounds 5 as a mixture of exo- and endo-(1:1) isomers along with 0.62 g of 6. The exo- and endo-isomers were partially separated by silica gel column and the stereochemistry have not assigned. Compound 5, less polar isomer: MS, m/z 376 (M+), 375. 1H NMR d 7.24-7.18 (m, 2H), 7.08-7.04 (m, 2H), 6.65 (s, 2H, C6,7 Hs), 5.61 (s, 1H), 5.33 (bs, 2H), 3.82 (s, 6H, OMe), 3.48 (s, 3H, OMe), 3.12 (ABd, J=9 Hz, 1H), 3.06 (ABd, J=9 Hz, 1H). More polar isomer: MS, m/z 376 (M+), 375. 1H NMR d 7.40 (m, 2H), 7.16 (m, 2H), 6.60 (ABd, J=8.8 Hz, 1H), 6.56 (Abd, J=8.8 Hz, 1H), 5.65 (s, 1H, ═CH), 5.33 (bs, 2H, C9,10 Hs), 3.76 (s, 3H, OMe), 3.73 (s, 3H, OMe), 3.51 (s, 3H, OMe), 3.13 (Abd, J=9 Hz, 1H), 3.08 (Abd, J=9 Hz, 1H). This mixture of compounds was used in the next step.
