20 The ratio of both diastereomers 3a,b considered
as kinetic products was estimated by ¹H NMR
spectroscopy and is different from that of their amidal congeners 9 in a 7:1 ratio.
21
Data for Compound
3b
Isolated in 51% yield as a white solid
(EtOAc-cyclohexane = 1:4); mp 136 ˚C; [α]D -20.9
(c 0.81×10-³,
CH2Cl2).
IR (KBr): νmax = 3019,
1687 cm-¹. ¹H
NMR (300 MHz, CDCl3): δ = 1.01 (s,
9 H), 3.33 (dd, 1 H, J = 12.0,
8.0 Hz), 4.64 (dd, 1 H, J = 12.3,
7.6 Hz), 4.80 (t, 1 H, J = 7.8
Hz), 7.25-7.38 (m, 5 HAr), 7.51 (t, 1 HAr, J = 7.2 Hz),
7.58 (t,
1 HAr, J = 7.2
Hz), 7.80 (d, 1 HAr, J = 7.2
Hz), 8.16 (d, 1 HAr, J = 7.2
Hz). ¹³C NMR (75 MHz, CDCl3): δ = 28.1,
51.7, 64.7, 75.9, 81.0, 122.8, 125.4, 126.8, 127.7, 128.9, 131.8, 132.7,
144.3, 153.6, 179.9. MS (EI): m/z = 350 [M+].
Anal. Calcd (%) for C21H22N2O3 (350.16):
C, 71.98; H, 6.33; N, 7.99. Found: C, 71.77; H, 6.18; N, 7.76.
27
Data for Compound
15a
Isolated in 35% yield as an orange solid
(EtOAc-cyclohexane = 2:3; R
f
= 0.17);
mp 171 ˚C; [α]D -212.4
(c 1.45×10-³,
CH2Cl2). IR (KBr): νmax = 3019,
1686 cm-¹. ¹H NMR
(300 MHz, CDCl3): δ = 2.02-20.7
(m, 1 H), 2.35-2.56 (m, 3 H), 3.91-4.03 (m, 1
H), 4.30 (s, 2 H), 4.81 (s, 1 H), 5.59 (s, 1 H), 7.12-7.24
(m, 5 HAr), 7.30-7.33 (m, 4 HAr),
7.44-7.48 (t, 1 HAr, J = 6.6
Hz), 7.56 (d, 1 HAr, J = 6.0
Hz), 7.67 (d, 1 HAr, J = 7.2
Hz), 7.75 (d, 1 HAr, J = 7.2
Hz). ¹³C NMR (75 MHz, CDCl3): δ = 29.8,
31.5, 39.3, 51.6, 59.1, 66.6, 123.7, 124.2, 126.0, 126.4, 127.3
(2×), 127.6, 127.8, 128.8, 129.2, 129.6 (2×),
132.0, 132.5, 134.4, 135.0, 140.9, 145.0, 167.5, 175.7. MS (EI): m/z = 394 [M+].
Anal. Calcd (%) for C26H22N2O2 (394.48):
C, 79.16; H, 5.62; N, 7.10. Found: C, 79.06; H, 5.52; N, 7.05.
Data for Compound 15b
Isolated
in 31% yield as an orange solid (EtOAc-cyclohexane = 2:3; R
f
= 0.11);
mp 216 ˚C; [α]D -210.9
(c 0.82×10-³,
CH2Cl2). IR (KBr): νmax = 3019,
1676 cm-¹. ¹H NMR
(300 MHz, CDCl3): δ = 1.50-1.57
(m, 1 H), 2.30-2.48 (m, 2 H), 2.50-2.65 (m, 1
H), 3.53 (dd, 1 H, J = 14.1,
3.7 Hz), 4.19 (d, 1 H, J = 8.0
Hz), 4.78 (dd, 1 H, J = 14.1
Hz), 5.54-5.56 (m, 2 H), 6.23-6.29 (m, 2 HAr),
6.56 (t, 2 HAr, J = 7.1
Hz), 6.71 (t, 1 HAr, J = 7.1
Hz), 6.84 (t, 1 HAr, J = 7.4 Hz),
6.98 (d, 1 HAr, J = 7.4
Hz), 7.13 (t, 1 HAr, J = 7.4
Hz), 7.46 (d, 1 HAr, J = 7.4
Hz), 7.55 (t, 1 HAr, J = 7.2
Hz), 7.63 (t, 1 HAr, J = 7.2
Hz), 7.81 (t, 1 HAr, J = 7.2
Hz), 7.95 (d, 1 HAr, J = 7.2
Hz). ¹³C NMR (75 MHz, CDCl3): δ = 29.2,
29.8, 42.1, 50.4, 58.9, 61.8, 123.4, 124.1, 125.0, 125.7 (2×),
126.7, 127.1, 127.8 (2×), 128.6, 129.0, 131.7, 132.1, 132.3,
132.9, 133.9, 141.8, 143.7, 167.9, 176.6; MS (EI): m/z = 394 [M+]. Anal.
Calcd (%) for C26H22N2O2 (394.48):
C, 79.16; H, 5.62; N, 7.10. Found: C, 78.96; H, 5.50; N, 6.93.
