NMRanalyst Sample Application: Brucine

Brucine
NMRanalyst Sample Application

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Sample Description:

Molecular Formula: C₂₃H₂₆N₂O₄
Molecular Weight: 394.464

InChI=

1/C23H26N2O4/c1-27-16-8-14-15(9-17(16)28-2)25-20(26)10-18-21-13-7-19-
23(14,22(21)25)4-5-24(19)11-12(13)3-6-29-18/h3,8-9,13,18-19,21-22H,4-7,10-
11H2,1-2H3/t13?,18?,19?,21?,22?,23-/m1/s1

IUPAC Name:

2,3-Dimethoxystrychnidin-10-one

CAS Number: 357-57-3
PubChem: 9649
NMRShiftDB: 20042191
Spectrometer: Varian INOVA 500 MHz
Solvent: CDCl₃
Sample Concentration: 5 mg

Provided by:

Dr. Dimitris Argyropoulos, Varian Deutschland GmbH

*.fid/text file specifies: Brucine... \| 5 mg in CDCl3
*.fid	np	nt	sw	rfp-rfl	ni	sw1	rfp1-rfl1	time

PROTON	17700	4	4668.53	-66.08				17 s
CARBON	78460	8192	30165.91	-1258.34				7 h 31 m
DQFCOSY	2048	2	4668.53	-66.08	512	4668.53	-66.08	1 h 2 m
gHMBC	2048	8	4668.53	-66.08	512	28905.99	0	2 h 3 m
gHSQC	1024	4	4668.53	-66.08	256	20110.61	-1.05	45 m 34 s
N15-gHMBC	2048	32	4668.53	-66.08	128	2025.82	4558.10	2 h 4 m

1D Proton Spectrum:

1D Carbon Spectrum (Deuterated Solvent Resonances Subtracted):

Automated VerifyIt Proton Assignments:

Automated VerifyIt Carbon Assignments:

Top 10 FindIt Molecular Structures Consistent With Molecular Formula and Proton Resonances:

The correct structure is at position 4.


 Best 10 structures in decreasing rating (structure ID shown in parentheses):
    1: 0.955525 (  220197)    2: 0.954765 (  276140)    3: 0.954085 (  220518)
    4: 0.953171 (    9649)    5: 0.949960 ( 3081763)    6: 0.949960 ( 5318514)
    7: 0.947528 (  633831)    8: 0.943049 ( 5319456)    9: 0.930901 ( 8394774)
   10: 0.929926 ( 8394719)

Top 10 FindIt Molecular Structures Consistent With Proton and Carbon Resonances:

The correct structure is at position 1.


 Best 10 structures in decreasing rating (structure ID shown in parentheses):
    1: 0.918970 (    9649)    2: 0.907258 (  458085)    3: 0.886418 (  161215)
    4: 0.884381 ( 5147853)    5: 0.880259 (  276140)    6: 0.879185 ( 6978343)
    7: 0.875640 (  220518)    8: 0.875138 (  220197)    9: 0.874196 (  275193)
   10: 0.865935 (  651999)

2D Multiplicity-Edited HSQC Spectrum:

Determined HSQC Correlations:

Top 10 FindIt Molecular Structures Consistent With Proton and Protonated Carbon (HSQC) Resonances:

The correct structure is at position 1.


 Best 10 structures in decreasing rating (structure ID shown in parentheses):
    1: 0.940963 (    9649)    2: 0.899355 (  264628)    3: 0.897448 (  220518)
    4: 0.893673 (  220197)    5: 0.892549 (  161215)    6: 0.891888 (  276140)
    7: 0.886883 (  253039)    8: 0.886714 (  458085)    9: 0.885339 ( 6978343)
   10: 0.885164 ( 3199155)

2D DQF-COSY Spectrum:

AssembleIt HSQC & DQF-COSY Derived Carbon-Carbon Correlations:

AssembleIt HSQC & DQF-COSY Derived Correlations

Entered HSQC & N15_HMBC Nitrogen-Carbon Correlations:

2D HMBC Spectrum:

AssembleIt HSQC, HMBC, DQF-COSY & N15_HMBC Derived Correlations:

AssembleIt Derived Structure With NMRgraph Added Likely Oxygen Atoms:

Most likely structure (out of 109 possible ones) by agreement with carbon chemical shift prediction

Comments:

Brucine is used as a denaturant in oils and alcohols, particularly in cosmetic preparations. It is also used in analytical chemistry for separating racemic mixtures.

The ¹⁵N resonance linewidths are over 20 Hz wide. Hence the acquisition of a large number of F1 resonances for the N15 HMBC causes an unacceptably low S/N. Furthermore, the acquired 90 to 129.8 ppm F1 sweep width does not contain the 37.00 or 151.0 ppm nitrogens of brucine. Fortunately, the strychnine (1mg) dataset has a similar molecular structure as brucine. So the observed strychnine N15 HMBC correlations with carbon shifts adjusted for the brucine carbons are used for this structure elucidation.

FindIt identifies the correct structure as the top one using proton and carbon, as well as proton and protonated carbon information.

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