KBS13-3 - Deprotection of bis-adamantyl cyclam

[KlementineJBS]

Link to HIRAC and original method.

HIRAC Deprotection of bis-adamantane cyclam .docx

Previous attempt was in Honours.

Reaction scheme

Outcome

339 mg (0.482 mmol), 86%

[KlementineJBS]

07.09.22

1. Dissolved *KBS12-2 (#30) (467 mg, 0.562 mmol) in dioxane (6 mL)

2. Added 3 drops water (more than needed - intended to add 1)

3. Added this solution to ice-cold HCl (4 M in dioxane, 0.5 mL, 2.00 mmol) at 4.05 pm

NOTE: some solution spilled in transfer

4. Allowed to warm to rt while stirring

TLC at 5 pm was inconclusive - product thought to be lowest Rf spot down the bottom (see previous attempt but unsure of why four spots appear. Previously, only top spot was seen - however, in #30, product appears around middle of TLC plate. Solvent system differed by addition of ammonium.

Eluent is 9:1:90 MeOH/NH4/DCM

[KlementineJBS]

08.09.22

TLC at 11 am still indicates reaction is not complete.

5. Added additional HCl (4 M, 0.5 mL, 2.00 mmol)

TLC at 1.30 pm indicated reaction was complete.

6. Removed dioxane via rotary evaporation and transferred to vial.

Empty vial: 15.9174 Full vial: 16.2568 Mass: 339.4 mg

12.09.23 full vial: 16.1573 Mass: 239.9 mg

[KlementineJBS]

09.09.22

LRMS

Peak at 631.49 [M+H]+.

KBS13-3 cr.d.zip KBS13-3 cr.pdf

Procedure

Converted some of product to free base for characterisation.

1. 100 mg product was dissolved in water (5 mL) and sodium hydroxide solution (2.5 M, 1 mL) was added.
2. Extracted with DCM (3 x 10 mL)
3. Rotovapped down and hivac'd to obtain swamp brown foam

Empty vial: 15.6804 Full vial: 15.7508 Mass: 70.4 mg (0.112 mmol), 79%

H NMR

21.1 mg in chloroform

KBS13-3 FB_1.zip KBS13-3 FB processed.pdf

(pdf includes comparison with 13-2 made last year)

Appears to be the same product.

[KlementineJBS]

12.09.22

Wanted to clean up free base so triturated with hexane. Accidentally used low-grade hexane first so repeated with spectroscopy grade hexane again afterwards (3 x 2 mL). Left on hi vac overnight.

[KlementineJBS]

13.09.22

NMR of free base after trituration looks cleaner, but with lingering hexane peaks. (Pdf contains triturated sample spectrum overlaid against previous sample spectrum.)

KBS13-3 FB 13-09-22_1.zip KBS13-3 FB 13-09-22 processed.pdf

Will hi vac overnight again and do quantitative NMR.

[KlementineJBS]

14.09.22

KBS13-3 FB 14-09-22_1.zip KBS13-3 FB 14-09-22 processed.pdf

NMR is cleaner, need to do quantitative. This sample was 20.3 mg.

[KlementineJBS]

16.01.23

Decided to pass some of the remaining HCl salt through a C18 column to purify as quantitative NMR suggested that the FB sample was < 95 % pure.

[KlementineJBS]

17.01.23

Letter	Fractions	Empty vial weight	Mass	LRMS
A	1-2	-	-	KBS13-3 HCl salt RP A.pdf
B	3-5	-	-	KBS13-3 HCl salt RP B.pdf
C	6-8	-	-	N/A
D	9-10	-	-	KBS13-3 HCl salt RP D.pdf
E	11-16	-	-	KBS13-3 HCl salt RP E.pdf

KBS13-3 HCl salt RP A B D E.zip

H NMR

KBS13-3 HCl salt reverse phase.pdf

KBS13-3 Hcl A_1.zip KBS13-3 Hcl B_1.zip KBS13-3 Hcl C_1.zip KBS13-3 Hcl D_1.zip KBS13-3 Hcl E_1.zip

All NMR spectra appear very similar but with subtle changes. Given that each sample ionised identically, it seems possible that the different fractions correspond to different ionisation states e.g. +1, +2.

Note that B and C have identical spectra.

[KlementineJBS]

18.01.23

Combined all five fractions and converted to free base using Ambersep 900.

Combined fractions were white and powdery with a combined mass of 127.4 mg.

Unpurified HCl salt (left) and purified HCl salt fractions (right):

1. Rinsed 2 spatulas of ambersep with methanol (x 3)
2. pre-swelled with methanol (~ 5 mL)
3. Added clean HCl salt (127.4 mg) dissolved in methanol (~ 15 mL)
4. Left stirring for ~50 minutes
5. Filtered with a Buchner funnel
6. Rotovapped down and hi-vacced

Note that conversion to free base can be seen on TLC - this was run in 90% DCM, 9% methanol, 1% ammonium hydroxide.

[KlementineJBS]

23.01.23

After Ambersep: Empty vial: 15.8195 Full vial: 15.9091 Mass: 89.6 mg

Put FB through an aluminum oxide plug - layered a small sintered funnel with filter paper, 3 cm neutral aluminium oxide and another filter paper. Applied vacuum and added enough ethyl acetate to wet all the aluminium oxide.

Added KBS13-3 FB (89.6 mg) dissolved in ethyl acetate and methanol, washed through with 1:9:90 ammonium hydroxide: methanol: DCM (3 x 10 mL). Rotovapped down filtrate.

Empty vial: 15.8089 Full vial: 15.8850 Mass: 76.1 mg

H NMR

Doesn't seem to be any cleaner than previous samples.

KBS13-3 FB 23-01-23_1.zip KBS13-3 FB 23-01-23.pdf

[KlementineJBS]

[KlementineJBS]

Prep HPLC