Scar's H-NMRs
Compounds A and B and Supporting H-NMR Spectra
The massadines, axinellamines, and palau'amines are all dimeric pyrrole imidazole alkaloids. These alkaloids are stereochemically challenging puzzles, but hold great potential for advancement of chemical synthesis. Compound A is an intermediate product in a reaction scheme to produce 1,9-dideoxy-pre-axinellamine. Through combination of Compound A, with PH3 and Compound B, reagents, in Trifluoroacetone (TFA), the above stated preaxiellamine is formed. Below are structures for compounds A(19) and B(20) and the following pages contain their H-NMR spectra and supporting evidence for identification.
H-NMR Spectra Justifications
Compound A (19)
Group Number |
Chemical Shift (sigma) |
Integration (# of H's) |
Explanation |
1 |
1.38-1.54 |
54 |
A group of 54 equivalent H's must be all the H's on Boc protecting groups. |
2 |
7.34 |
1 |
H located on an aromatic ring next to a deshielding N-atom. |
3 |
4.00 |
1 |
This peak is a doublet meaning H attached has 1 3-bond neighbor. |
4 |
2.24-2.30 |
1 |
Slightly less desheilded than Group 6, Has multiplet because of many 3-bond neighbors. |
5 |
3.35-3.63 |
2* |
Similar to Groups 7 and 9 because each is attachd to N and sp3-C atoms. |
6 |
2.42-2.49 |
1 |
More deshielded than Group 4 because it is closer to Cl atom. Has multiplet because of many 3-bond neighbors. |
7 |
3.35-3.63 |
2* |
Similar to Groups 5 and 9 because each is attachd to N and sp3-C atoms. |
8 |
4.33 |
1 |
Peak is a doublet, has 1 3-bond neighbor and is nearby to deshielding Cl atom. |
9 |
3.35-3.63 |
|
Similar to Groups 5 and 7 because each is attachd to N and sp3-C atoms. |
*Area on NMR cannot be definitively associated with each group. The total integration of sigma3.35-3.63 is 6H.
Compound B (20)
Group Number |
Chemical Shift (sigma) |
Integration (# of H's) |
Explanation |
1 |
10-13 |
1 |
H on an ester group should be at chemical shift of 10-13. NMR only reaches 10 and there are 6 groups of H's where only 5 are shown on spectra. Also, sometimes H on carboxylic acid is not detected in NMR. |
2 |
7.21 |
1 |
H located on an aromatic ring. |
3 |
5.81 |
2 |
A pair of H's between N and O (both have deshielding effect on H's). |
4 |
3.60 |
2 |
Pair of H's are adjacent to O atom (deshielded) |
5 |
0.91 |
2 |
H's between two atoms that are shielding. |
6 |
-0.03 |
9 |
An integration of 9H denotes Group 6. |
____SIMBA'S_______-NALA's________RAFIKI'S ______PUMBA & TIMON'S _____-SCAR'S
Leading Questions------Citations_____Experimental_______Mechanism----------___---H-NMRs
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