4
300 MHz): δ = 7.39-7.25 (m, 5 H, aromatic), 5.07 (dist d, J = 15.2, 1 H, PhCHH), 4.76 (s, 1 H, =CHH), 4.26 (s, 1H,
=CHH), 4.11 (dist d, J = 15.2, 1 H, PhCHH), 3.52-3.38 (m, 1 H, NCH), 2.59 (dist dd, J = 14.3, 5.5, 1 H, CHHCO),
2.29 (dist dd, J = 12.3, 2.2, 1 H, CHHCO), 1.18 (d, J = 6.5, 3 H, Me); 13C NMR (CDCl3, 75 MHz): δ = 151.11,
151.07, 136.7, 128.8, 127.9, 127.8, 94.3, 50.5, 47.9, 32.9, 18.1; GC-MS (EI, 70 eV): m/z = 217 (M+, 22), 132 (4),
+
112 (6), 91 (100); HRMS (ESI-TOF) m/z: [(M+H)+] cald for C13H16NO2 : 218.1176; found, 218.1197.
2.2.8. 4-Methyl-6-methylene-3-phenethyl-1,3-oxazinan-2-one 2h (Yield: 121 mg, 75% based on starting 1h).
Yellow solid, mp 52-53 °C. IR (film): ν = 1701 (s), 1663 (s), 1450 (w), 1420 (m), 1217 (w), 1194 (w), 704 (m)
1
cm−1; H NMR (CDCl3, 300 MHz): δ = 7.36-7.18 (m, 5 H, aromatic), 4.71 (s, 1 H, =CHH), 4.20 (s, 1 H, =CHH),
3.97-3.84 (m, 1H, NCH), 3.21-2.83 (m, 4 H, CH2CH2Ph), 2.46 (dist dd, J = 14.2, 5.4, 1 H, CHHC=), 2.16 (dist dd,
J = 14.2, 1.8, 1 H, CHHC=), 1.11 (d, J = 6.5, 3 H, Me); 13C NMR (CDCl3, 75 MHz): δ = 151.1, 150.4, 138.8, 128.9,
128.6, 126.6, 94.1, 50.2, 34.2, 32.6, 18.6; GC-MS (EI, 70 eV): m/z = 231 (M+, 58), 216 (12), 140 (78), 105 (59),
+
104 (61), 91 (100); HRMS (ESI-TOF) m/z: [(M+H)+] cald for C14H18NO2 : 232.1332; found, 232.1359.
2.2.9. 3-Benzyl-4-ethyl-6-methylene-1,3-oxazinan-2-one 2i (Yield: 131 mg, 81% based on starting 1i). Yellow
oil. IR (film): ν = 1717 (s), 1663 (m), 1447 (w), 1188 (m), 1128 (w) cm−1; 1H NMR (CDCl3, 300 MHz): δ = 7.41-
7.20 (m, 5 H, aromatic), 5.15 (dist d, J = 15.3, 1 H, PhCHH), 4.73 (s, 1 H, =CHH), 4.23 (m, 1 H, =CHH], 4.06 (dist
d, J = 15.3, 1 H, PhCHH), 3.20-3.15 (m, 1 H, NCH), 2.46 (dist d, J = 2.9, 2 H, CH2C=), 1.80-1.61 (m, 1 H, CHHCH3),
1.61-1.40 (m, 1 H, CHHCH3), 0.87 (t, J = 7.4, 3 H, Me); 13C NMR (CDCl3, 75 MHz): δ = 151.3, 151.2, 136.8, 128.8,
127.9, 127.8, 93.9, 53.7, 51.0, 29.6, 24.7, 10.3; GC-MS (EI, 70 eV): m/z = 231 (M+, 12), 202 (5), 126 (4), 91
+
(100); HRMS (ESI-TOF) m/z: [(M+H)+] cald for C14H18NO2 : 232.1332; found, 232.1358.
2.2.10. 4-Ethyl-6-methylene-3-phenethyl-1,3-oxazinan-2-one 2j (Yield: 131 mg, 76% based on starting 1j).
Yellow solid, mp 64-65 °C. IR (KBr): ν = 1713 (s), 1661 (m), 1452 (m), 1422 (w), 1219 (m), 1194 (w), 752 (m),
704 (m) cm−1; 1H NMR (CDCl3, 300 MHz): δ = 7.36-7.17 (m, 5 H, aromatic), 4.67 (s, 1 H, =CHH), 4.17 (s, 1 H,
=CHH), 4.07-3.95 (m, 1 H, NCH), 3.16-2.75 (m, 4 H, CH2CH2Ph), 2.32 (d, J = 3.3, 2 H, CH2C=), 1.69-1.50 (m, 1 H,
CHHCH3), 1.50-1.31 (m, 1 H, CHHCH3), 0.84 (t, J = 7.4, 3 H, Me); 13C NMR (CDCl3, 75 MHz): δ = 151.3, 150.4,
138.8, 128.9, 128.6, 126.6, 93.7, 56.1, 50.9, 34.1, 29.3, 25.4, 10.3; GC-MS (EI): m/z = 245 (M+, 26), 154 (61),
+
105 (45), 104 (47), 91 (100); HRMS (ESI-TOF) m/z: [(M+H)+] cald for C15H20NO2 : 246.1489; found, 246.1517.
2.2.11. 3-Benzyl-6-methylene-4-phenyl-1,3-oxazinan-2-one 2k (Yield: 153 mg, 78% based on starting 1k).
White solid, mp 71-72 °C. IR (KBr): ν = 1717 (s), 1663 (m), 1443 (w), 1423 (w), 1196 (m), 1153 (w), 748 (m),
702 (w) cm−1; 1H NMR (CDCl3, 300 MHz): δ = 7.45-7.10 (m, 10 H, aromatic), 5.31 (dist d, J = 15.1, PhCHH), 4.70
(s, 1 H, =CHH), 4.51-4.35 (m, 1 H, PhCH), 4.05 (s, 1 H, =CHH), 3.67 (dist d, J = 15.1, PhCHH), 2.86 (dist dd, J =
14.2, 6.2, 1 H, CHHC=), 2.48 (dist dd, J = 14.2, 2.1, 1 H, CHHC=); 13C NMR (CDCl3, 75 MHz): δ= 151.5, 150.1,
138.7, 136.2, 128.9, 128.8, 128.3, 128.2, 127.9, 126.3, 95.0, 56.0, 50.6, 34.3; GC-MS (EI, 70 eV): m/z = 279
+
(M+, 15), 146 (13), 104 (100), 91 (48); HRMS (ESI-TOF) m/z: [(M+H)+] cald for C18H18NO2 : 280.1332; found,
280.1327. The spectroscopic properties were in good agreement with those reported [8].
2.2.12. 3-Benzyl-5,5-dimethyl-6-methylene-4-phenyl-1,3-oxazinan-2-one 2l (Yields: 144 mg, 67% based on
starting 1l). White solid, mp 165-166 °C. IR (KBr): ν = 1713 (s), 1659 (m), 1443 (w), 1427 (w), 1211 (m), 1173
(m), 1103 (w), 702 (m) cm−1; 1H NMR (CDCl3, 300 MHz): δ = 7.42-7.20 (m, 8 H aromatic), 7.20-7.05 (m, 2 H,
aromatic), 5.28 (dist d, J = 14.7, 1 H, PhCHH), 4.76 (d, J = 1.6, 1 H, =CHH), 4.10 (d, J = 1.6, 1 H, =CHH), 3.73 (s,
1 H, PhCH), 3.48 (dist d, J = 14.7, PhCHH), 1.17 (s, 3 H, Me), 0.73 (s, 3 H, Me); 13C NMR (CDCl3, 75 MHz): δ =
158.4, 151.0, 137.1, 136.2, 129.0, 128.7, 128.54, 128.47, 128.0, 127.8, 92.6, 66.9, 50.4, 36.6, 27.3, 22.9; GC-
MS (EI, 70 eV): m/z = 307 (M+, 24), 240 (3), 216 (5), 194 (7), 174 (16), 132 (100), 117 (38), 91 (92); HRMS (ESI-
+
TOF) m/z: [(M+H)+] cald for C20H22NO2 : 308.1645; found, 308.1656.
2.2.13. 4-Methyl-6-methylene-3-(1-phenylethyl)-1,3-oxazinan-2-one 2m (Mixture of diastereoisomers A+B,
1
A/B ratio ~ 1.3, by HNMR; yield: 84 mg, 52% based on starting 1m) Yellow oil. IR (film): ν = 1711 (s), 1663
(m), 1420 (w), 1184 (m), 1024 (w), 700 (w) cm−1; 1H NMR (CDCl3, 300 MHz): δ = 7.46-7.25 (m, aromatic, A+B),
5.74 (q, J = 7.1, CHPh, B), 5.65 (q, J = 7.0, CHPh, A), 4.72 (s, =CHH, B), 4.70 (s, =CHH, A), 4.18 (s, =CHH, A), 4.17