ORDER
REPRINTS
METHYL 3-ALKOXYBENZOATES
459
1
the cyclohexadienone 3a (1.24 g, 48%) as an oil. H NMR (200 MHz, CDCl3)
δ 1.42 (t, J = 7.0 Hz, 3H, CH3), 2.94 and 2.84 (AB quartet, J = 16.0 Hz, 2H,
CH2CO2), 3.74 (s, 3H, OCH3), 3.75 (s, 3H, OCH3), 3.88 (dq, J = 7.0, 1.7 Hz,
2H, OCH2), 5.91 (d, J = 2.6 Hz, 1H, CH), 6.40 (d, J = 10.0 Hz, 1H, CH), 7.08
(dd, J = 10.0, 2.6 Hz, 1H, CH); 13C NMR 180.1, 170.9, 170.2, 151.3, 146.2,
130.1, 114.1, 114.0, 63.5, 53.4, 52.1, 50.0, 42.3, 14.0; MS (EI) m/z (relative in-
tensity) 268 (M+, 12), 236 (37), 209 (59), 165 (40), 149 (48), 136 (100), 107 (22),
59 (68); HRMS (EI) calcd for C13H16O6 268.0947, Found 268.0943.
Methyl 2-(3-isopropoxy-1-methyloxycarbonyl-4-oxo-2,5-cyclohexadie-
nyl)acetate (3b). Cyclohexadienone 3b was prepared in 46% yield from the
cyclohexadiene 2b as described for 3a. Flash chromatography (silica gel, hexane–
ethyl acetate 4:1) provided an oil. 1H NMR (200 MHz, CDCl3) δ 1.34 (dd, J = 6.1,
1.3 Hz, 6H, CH3), 2.92 (s, 2H, CH2CO2), 3.71 (s, 3H, OCH3), 3.76 (s, 3H,
OCH3), 4.39 (septet, J = 6.1 Hz, 1H, OCH), 5.98 (d, J = 2.7 Hz, 1H, CH), 6.40
(d, J = 10.0 Hz, 1H, CH), 7.07 (dd, J = 10.0, 2.7 Hz, 1H, CH); 13C NMR 180.2,
170.7, 169.8, 149.6, 145.6, 130.1, 115.6, 69.7, 53.2, 51.9, 49.9, 42.1, 21.1, 21.0;
MS (EI) m/z (relative intensity) 282 (M+, 1), 223 (36), 176 (27), 152 (6), 137
(100); HRMS (EI) calcd for C14H18O6 282.1103. Found 282.1101.
Methyl 2-(3-butoxy-1-methyloxycarbonyl-4-oxo-2,5-cyclohexadienyl)
acetate (3c). Cyclohexadienone 3c was prepared in 66% yield from the cyclo-
hexadiene 2c as described for 3a. Flash chromatography (silica gel, hexane–ethyl
acetate 4:1) provided an oil. 1H NMR (200 MHz, CDCl3) δ 0.96 (t, J = 7.4 Hz,
3H, CH3), 1.46 (qt, J = 7.4, 7.1 Hz, 2H, CH2), 1.79 (tt, J = 7.1, 6.7 Hz, 2H, CH2),
2.96 and 2.85 (AB quartet, J = 16.5 Hz, 2H, CH2CO2), 3.71 (s, 3H, OCH3), 3.75
(s, 3H, OCH3), 3.79 (t, J = 6.7 Hz, 2H, OCH2), 5.92 (d, J = 2.6 Hz, 1H, CH),
6.40 (d, J = 10.0 Hz, 1H, CH), 7.10 (dd, J = 10.0, 2.6 Hz, 1H, CH); 13C NMR
179.8, 170.8, 170.0, 151.3, 145.9, 130.0, 113.8, 67.6, 53.3, 52.0, 49.8, 42.2, 30.5,
19.1, 13.7; MS (EI) m/z (relative intensity) 296 (M+, 4), 265 (56), 237 (49),
181 (65), 137 (100), 107 (9); HRMS (EI) calcd for C15H20O6 296.1260. Found
296.1260.
Methyl 2-(3-phenoxy-1-methyloxycarbonyl-4-oxo-2,5-cyclohexadienyl)
acetate (3d). Cyclohexadienore 3d was prepared in 43% yield from the cyclo-
hexadiene 2d as described for 3a. Flash chromatography (silica gel, hexane–ethyl
acetate 4:1) provided an oil. 1H NMR (200 MHz, CDCl3) δ 2.87 (s, 2H, CH2CO2),
3.66 (s, 3H, OCH3), 3.74 (s, 3H, OCH3), 6.17 (d, J = 2.6 Hz, 1H, CH), 6.46 (d,
J = 10.0 Hz, 1H, CH), 6.99–7.03 (m, 1H, CH), 7.06–7.17 (m, 3H, ArH), 7.30–
7.38 (m, 2H, ArH); 13C NMR 179.6, 170.1, 169.7, 154.9, 151.2, 146.2, 130.4,
129.8, 124.4, 123.3, 119.2, 53.6, 50.5, 41.6; MS (EI) m/z (relative intensity) 316