ORDER
REPRINTS
3-ARYLCOUMARINS
2757
in N,N-dimethylaniline (15 ml) was refluxed, under nitrogen atmosphere, for
4–12 h (monitored by TLC). Excess of N,N-dimethylaniline was removed
underreducedpressure.Theresiduewasextractedwithethylacetate(3Â15 ml),
washed first with dilute hydrochloric acid and finally with water. The com-
bined organic layer was dried over anhydrous Na2SO4 and evaporated. The
residue was chromatographed over silica gel using pet. ether–ethyl acetate
(98:2) as an eluent to provide 6-prenyl-3-arylcoumarins (7a–d) in initial
fractions. In the reaction of 4,6-dimethoxy-2-prenyloxybenzaldehyde (5b)
with phosphoranes 6a and 6b, the 6-prenyl-3-arylcoumarins 7c and 7d
were obtained in the initial fractions and the 8-isoprenyl-3-arylcoumarins
8c and 8d in later fractions. All these solid products were recrystallized from
pet. ether–ethyl acetate.
7-Methoxy-6-prenyl-3-phenylcoumarin (7a). A mixture of 5a and 6a
was refluxed for 12 h to give 7a in 37% yield, mp 77–78ꢀC, nmax/cmÀ1
(Nujol) 1716(C ¼O); dH 1.71 (3H, s, CH3), 1.78 (3H, s, CH3), 3.33 (2H,
d, J 7.3 Hz, ArCH2CH¼), 3.91 (3H, s, OCH3), 5.3 (1H, m, ArCH2CH¼),
6.81 (1H, s, 8-H), 7.24 (1H, s, 5-H), 7.4–7.46 (3H, m, Ar-H), 7.67–7.7 (2H,
m, Ar-H), 7.76(1H, s, 4-H) (Found: C, 78.58; H, 6.42. C 21H20O3 requires C,
78.72; H 6.29%).
20,5-Dideoxy-40-O-methylglycyrin (7b). A mixture of 5a and 6b was
refluxed for 11 h to give 7b in 38% yield, mp 97–99ꢀC, nmax/cmÀ1 (Nujol)
1717 (C¼O); dH 1.71 (3H, s, CH3), 1.77 (3H, s, CH3), 3.32 (2H, d, J 7.3 Hz,
ArCH2CH¼), 3.85 (3H, s, OCH3), 3.9 (3H, s, OCH3), 5.3 (1H, m,
ArCH2CH¼), 6.8 (1H, s, 8-H), 6.96 (2H, d, J 8.8 Hz, Ar-H), 7.23 (1H, s,
5-H), 7.65 (2H, d, J 8.8 Hz, Ar-H), 7.7 (1H, s, 4-H) (Found: C, 75.64; H,
6.22. C22H22O4 requires C, 75.41; H, 6.33%).
5,7-Dimethoxy-6-prenyl-3-phenylcoumarin (7c). A mixture of 5b and 6a
was refluxed for 4 h to give 7c (20% yield) in the initial fractions, mp
133–135ꢀC, nmax/cmÀ1 (Nujol) 1720 (C¼O); dH 1.69 (3H, s, CH3), 1.79
(3H, s, CH3), 3.37 (2H, d, J 6.8 Hz, ArCH2CH¼), 3.85 (3H, s, OCH3),
3.89 (3H, s, OCH3), 5.16(1H, m, ArCH 2CH¼), 6.66 (1H, s, 8-H),
7.38–7.48 (3H, m, Ar-H), 7.68–7.76 (2H, m, Ar-H), 7.98 (1H, s, 4-H)
(Found: C, 75.21; H, 6.55. C22H22O4 requires C, 75.41; H 6.33%).
Further elution with the same solvent gave 8c in 10% yield.
5,7-Dimethoxy-8-(isoprenyl)-3-phenylcoumarin (8c). Mp 158–160ꢀC,
n
max/cmÀ1 (Nujol) 1708 (C¼O); dH 1.67 (6H, s, 2 Â CH3), 3.85 (3H, s,
OCH3), 3.94 (3H, s, OCH3), 4.87 (1H, dd, J 1.1 and 10.4 Hz, CH2¼), 4.89
(1H, dd, J 1.1 and 17.4 Hz, CH2¼), 6.3 (1H, dd, J 17.4 and 10.4 Hz, CH¼),
6.33 (1H, s, 6-H), 7.34–7.46 (3H, m, Ar-H), 7.72–7.76 (2H, m, Ar-H), 8.15
(1H, s, 4-H) (Found: C, 75.38; H, 6.47. C22H22O4 requires C, 75.41; H, 6.33%).
20-Deoxy-40-O-methylglycyrin (7d). A mixture of 5b and 6b was reflu-
xed for 10 h to give 7d in (27% yield) in the initial fractions, mp 102–104ꢀC,