N
X
C
O
N
S
Hal
Solvents
Natural
Products
P Si
C
C
C C
C
C
234
5 1 H NMR
Lactams (δ in ppm, J in Hz)
NH
H
H
H
H
H H
O
O
N
N
O
O
N
H
O
N
H
N
H
H
H
H
H H
O
≈ 40%
≈ 60%
O
N
O
N
1.99
5.56
4.11
1.15
2.83
2.05
3.42 1.96
1.86
3.46
4.52
1.03
3.92
2.70
1.85
1.51
1.03
1.66
1.04
0.87
1.01
0.84
5.42
3.67
2.01
1.07
1.11
1.78
2.18
2.08
3.40
1.64*
1.57*
1.54*
3.54
7.49
7.32
7.11
3 J ab 8.2
4 J ac 1.2
5 J ad 0.5
4 J ae 2.4
3 J bc 7.4
4 J bd 1.5
e
d
c
b
a
HN
O
N
O
HN
O
N
O
HN
NH
O
O
HN
O
N
O
2.75
2.94
6.06
2.85
3.40
3.39
3 J HNCH 2
0.8
3 J HNCH 2
2.2
2.14
2.03
2.30
2.37
2.36
2.37
3.35
6.35
2.98
3.36
1.66
2.46
2.52
1.69
1.75
1.70
1.65
1.65
3.21
8.00
1.81
1.82
3.31
3.29
1.79
1.81
6.33
3.20
2.82
* assignment uncertain