case, the result is a large number of NMR spectra, most ... proton spectrum only, as the additional information contained in ... proton only approach. ... all spectral signals can be assigned to the structure ... their associated structures. ... two major causes were to blame. ... favorable tautomer than the one that was drawn, or the.
Poster Presented at ENC 2008, Pacific Grove, CA, USA, March 12–13, 2008
Validating the Quality of Large Collections of NMR Spectra Automatically Sergey S. Golotvin, Eugene Vodopianov, Rostislav Pol, Mikhail Kvasha, Leandro Berry, and Brent A. Lefebvre Advanced Chemistry Development, Inc. Toronto, ON, Canada Jim Brien and Chris Lein Sigma-Aldrich Corp., Milwaukee, WI, USA
M01(s,16)
O 15 5
M06(d,7)
7.35
12
9
6
N
3
7
4 8
2
M07(m,11,13,12,10,14)
13 14
O CH3 1 16
Consistent
TMS
M05(d,6)
M04(m,3)
8.0
7.5
7.0
6.5
6.0
5.5
5.0
4.5 4.0 3.5 Chemical Shift (ppm)
2.95
1.03
0.94
0.89
4.68 8.5
-0.01
5.10 5.07 5.05 4.70 4.67 4.64 4.32 4.30 4.30 4.27
7.13 7.11
6.10 6.08
M03(m,2)
1.03
7.36
M02(dd,2, 14, 19a are unassigned - not enough appropriate multiplets around 2.1, 4.8, 6.7 ppm
H split between these categories was fairly even and can be O CH seen in Table 1. O In the case of failures due to the experimental spectrum, N CH H the acute causes were more varied. These causes OH OH O included the presence of a related impurity or isomer, O Inconsistent some that were unexplained, some that failed due to interference from the solvent or water peak, and some that failed for various other reasons. In the cases of spectra that failed due to structure issues, two major causes were to blame. The presence of a more favorable tautomer than the one that was drawn, or the conclusion that the structure was actually incorrect. Figure 3 is an example of an incorrect structure, and how Figure 4—An example of another inconsistent match. In this example the atoms 19a and 20 are on the wrong this is treated by the software. sides of this double bond. M07(ddd,17)
M01(m)
1D HNMR Verification Warning: Expected multiplet for atom(s) 12 at 1.7 ppm is not detected
M06(m,6)
8.0
M10(m)
M12(m)
5.69 5.68 5.66 5.66
0.96
5.71 5.71
8.07
8.5
M13(m)
M14(t,2) M11(m,3a) 4.95
M16(m,16) M15(m)
M17(m)
0.99
25
3.52
24
22
13
0.76
3.53
11
12
16
5.42 5.38
14
3 21 23
3.19 3.16 3.14 2.50 2.48 2.56 2.46 2.55 2.32 2.30 2.27 2.25 2.19 2.09 1.99 2.07 2.15
10
15
17
1.80
M06(t,5)
1
3a
M04(m,6)
M08(m,23,23
