Ring Opening of ꢀ-Epoxyketones
1051
3
ꢀꢂA 7.10, ꢂB 7.85, j JABj 7.7 Hz, 4H, aromaticH), 7.30 ꢀbs, 5H, aromaticH) ppm; EI-MS ꢀ70 eV,
50ꢁC): m=z ꢀ%) 238 [M ±CH3COCH3] ꢀ21), 190 [M ±C6H5CHO] ꢀ32), 177 [M ±CH3C6H4CO]
ꢀ49), 119 [CH3C6H4CO ] ꢀ100), 91 C7H7 ꢂ86, 77 C6H5 ꢂ32; zone 2: 56 mg ꢀ24%) of 4c,
washed with n-pentane=ether, m.p.: 132±133ꢁC.
cis-2,2-Dimethyl-4-p-methylbenzoyl-5-phenyl-1,3-dioxolane ꢀ4c; C19H20O3)
1
IR ꢀKBr): ꢁ 3045, 2900±2995, 1685, 1610 cmÀ 1; H NMR: ꢂ 1.52 ꢀs, 3H, CH3), 1.80 ꢀs, 3H,
3
CH3), 2.24 ꢀs, 3H, CH3), AB-system ꢀꢂA 5.48, ꢂB 5.74, j JABj 7.6 Hz, 2H, 4-H, 5-H), AB-system
3
ꢀꢂA 6.90, ꢂB 7.35, j JABj 7.7 Hz, 4H, aromaticH), 6.98 ꢀs, 5H, aromaticH) ppm; EI-MS ꢀ70 eV,
50ꢁC): m=z ꢀ%) 281 [M ±CH3] ꢀ0.3), 238 [M ±CH3COCH3] ꢀ21), 190 [M ±C6H5CHO] ꢀ8), 177
[M ±CH3C6H4CO] ꢀ12), 119 [CH3C6H4CO ] ꢀ100), 91 C7H7 ꢂ37, 77 C6H5 ꢂ3; zone 3: 64 mg
ꢀ41%) of 5a, recrystallized from ethanol=ether, m.p.: 87±89ꢁC ꢀRef. [18]: 90ꢁC).
p-Methylbenzoylmethanol ꢀ5a; C9H10O2)
IR ꢀKBr): ꢁ 3350±3410, 3050, 2990, 1679, 1610 cmÀ 1; 1H NMR: ꢂ 2.39 ꢀs, 3H, CH3), 3.26 ꢀbr s,
3
1H, OH), 4.79 ꢀs, 2H, CH2), AB-system ꢀꢂA 7.22, ꢂB 7.77, j JABj 7.5 Hz) ppm.
Irradiation of 3-p-methoxyphenyl-1-phenyl-2,3-epoxy-1-propanone ꢀ1d; C16H14O3)
PLC, petroleum ether:ethyl acetate 10:1, two times; zone 1: 28 mg ꢀ11%) of 3d, washed with n-
pentane=ether, m.p.: 43±47ꢁC ꢀRef. [15]: 47±48ꢁC).
trans-4-Benzoyl-5-p-methoxyphenyl-2,2-dimethyl-1,3-dioxolane ꢀ3d; C19H20O4)
1
IR ꢀKBr): ꢁ 3060, 2840±2990, 1688, 1616, 1595 cmÀ 1; H NMR: ꢂ 1.43 ꢀs, 3H, CH3), 1.60 ꢀs,
3
3H, CH3), 3.77 ꢀs, 3H, OCH3), AB-system ꢀꢂA 5.20, ꢂB 5.51, j JABj 7.2 Hz, 2H, 4-H, 5-H), AB-
3
system ꢀꢂA 6.94, ꢂB 7.29, j JABj 8.2Hz, 4H, aromaticH), 7.40±8.00 ꢀm, 5H, aromaticH) ppm;
zone 2: 74mg ꢀ29%) of 4d, recrystallized from n-hexane, m.p.: 127±129ꢁC.
cis-4-Benzoyl-5-p-methoxyphenyl-2,2-dimethyl-1,3-dioxolane ꢀ4d; C19H20O4)
1
IR ꢀKBr): ꢁ 3010, 2860±2950, 1688, 1620 cmÀ 1; H NMR: ꢂ 1.52 ꢀs, 3H, CH3), 1.79 ꢀs, 3H,
3
CH3), 3.62 ꢀs, 3H, OCH3), AB-system ꢀꢂA 5.47, ꢂB 5.73, j JABj 7.6 Hz, 2H, 4-H, 5-H), AB-
3
system ꢀꢂA 6.49, ꢂB 6.98, j JABj 8.2Hz, 4H, aromaticH), 7.15±7.55 ꢀm, 5H, aromaticH) ppm;
EI-MS ꢀ70 eV, 60ꢁC): m=z ꢀ%) 312 [M ] ꢀ3), 254 [M ±CH3COCH3] ꢀ29), 176 [M ±C6H5CO±
OCH3] ꢀ54), 161 [M ±C6H5CO±OCH3±CH3] ꢀ47), 149 [M ±CH3COCH3±C6H5CO] ꢀ23), 105
[C6H5CO ] ꢀ100), 77 C6H5 ꢂ35; zone 3: 45mg ꢀ21%) of 6.
Irradiation of 1-p-methylphenyl-3-phenyl-2,3-epoxy-1-propanone ꢀ1e; C16H14O3)
PLC, petroleum ether:ethyl acetate 10:1, two times; zone 1:20mg ꢀ8%) of 3e, visc ose oil.
trans-4-p-Methoxybenzoyl-2,2-dimethyl-5-phenyl-1,3-dioxolane ꢀ3e; C19H20O4)
IR ꢀ®lm): ꢁ 3045, 2840±2920, 1680, 1598 cmÀ 1; 1H NMR: ꢂ 1.42 ꢀs, 3H, CH3), 1.59 ꢀs, 3H, CH3),
3
3.79 ꢀs, 3H, OCH3), AB-system ꢀꢂA 5.18, ꢂB 5.47, j JABj 7.1 Hz, 2H, 4-H, 5-H), AB-system
3
ꢀꢂA 6.81, ꢂB 7.90, j JABj 8.1 Hz, 4H, aromaticH), 7.35 ꢀs, 5H, aromaticH) ppm; EI-MS ꢀ70 eV,
150ꢁC): m=z ꢀ%) 254 [M ±CH3COCH3] ꢀ92), 177 [M ±CH3OC6H4CO] ꢀ23), 135 [CH3OC6H4