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8th December 2016 @ 23:56

deprotect.jpg

Compound

Mw (g/mol)

mmol

mL

g

equiv

Starting Material

526.6501

0.09494

 

50mg

1

HCl-Ether

38

0.0312

0.156 (2M HCl)

 

3.3

Product

Theoretical Values

339.17

0.09494

 

32.2mg

1

dioxane

88.11

 

2 mL (4M)

 

3.3

Product Actual Value

339.17

0.07371

 

25.0 mg

78% Yield

 

November 30, 2016

Procedure:

  1. Dissolve 50 mg of the starting material in 500 uL of anhydrous diethyl ether and place system under argon.

  2. Add 2M HCl-Ether (0.1 mL) dropwise to the solution while stirring.

  3. Age solution for 2 hours at room temperature and the reaction was monitored with TLC.

  4. Left in fridge overnight.

the nemesis deprot round 2.jpg

100% EtOAc solvent system, silica gel plate, UV visualization

S → Starting Material; C → Co-spot; P → Product.

This TLC is similar to the first deprotection we did, which we deemed unsuccessful in taking out that BOC group, though there was success in knocking out the THP. This can be determined by comparing the S and C to the P. The S and C show a dark spot higher up on the plate; P shows one lower with a faint smear above it. This suggests that the THP group was successfully knocked out and the BOC group only partially (this agrees with our NMR and GCMS results from the first deprotection). Another TLC was done to confirm this hypothesis and determine if the reaction should be hit harder to take out both the THP and BOC group.

  the nemesisdeproround2.jpg

100% EtOAc solvent system, silica gel plate, dipped in ninhydrin and treated with heat

S1→ Original Purified Starting Material; S2→ Starting Material from First Deprotection; C → Co-spot; P → Product.

Treating the TLC plate with ninhydrin and heat results in two dark spots on the base line of S2, and C and a faint brown spot on the base line of P. The difference in intensity can be attributed to concentration. The presence of these spots after being treated with heat suggest that the BOC group was successfully knocked off, and resulted in the formation of an amine, which is the desired product. The BOC was only successful knocked off with heat on the plate. To do this on a larger scale, these results suggests the deprotection reaction must be hit harder; the reaction must be done under heat with the addition of dioxane.

 

December 5, 2016

We were unsuccessful in removing the BOC with extra time . This suggests the reaction needs to be hit harder, specifically with the addition of dioxane and ran in an oil bath.

  1. Added 2 ml of 4M Dioxane and 0.1 mL of HCl  dropwise to the product while stirring and place in an oil bath at 50 degrees Celsius. System was placed under argon.  The reaction was monitored with TLC.

  2. After 2 hours at 50 degrees, TLC indicated that there was still starting material. The temperature was raised to 102 degrees to induce reflux. The reaction was then left to reflux for 45 minutes.

  3. After 45 minutes the reaction turned brown and a TLC was taken. The results of the TLC and a ninhydrin test suggest that the complete deprotection was successful due to the disappearance of the high Rf spot observed in previous attempts.

 

December 7, 2016

Mass Spec:

 
Deprotection.pdf
 

The peak at m/z 340 suggests that we successfully removed the Boc protecting group that we had trouble removing in the past. It is possible, however, some residual Boc protecting groups were removed in the mass spec instrument, so the product was also analyzed with proton and carbon NMR.

 
December 8, 2016 

NMR:

Still to be determined

 
Attached Files
Deprotection.pdf