KBS50-1 - Nosyl protection of bis(3-aminopropyl)amine

[KlementineJBS]

Link to HIRAC and master page #157

KBS43 - Nosyl protection of linear diamine .docx

Reaction scheme

[KlementineJBS]

1. Added SM amine (449.6 mg, 3.43 mmol) to a flask
2. Added chloroform (10 mL)
3. Added NEt3 (1.4 mL, 10.38 mmol, 3 equiv.)
4. Cooled to 0 C
5. Added nosyl chloride (1.671 g, 7.56 mmol, 2.2 equiv.) with ~ 10 mL extra chloroform
6. Left stirring from ~ 2.30 until 4.45 pm

TLC indicated reaction was progressing, but unsure what spots correspond to what. Ideally, reaction should occur twice at terminal amines. SM was consumed.

Turned off stirring and left overnight awaiting MS analysis.

Eluent was 10% MeOH in DCM with NH4OH, stained with ninhydrin.

[KlementineJBS]

LRMS

Evidence of desired product, 502.205+ [M+H]+ as well as over-nosylated product 685.15- [M-H]- , 709.01+ [M+Na]+ and 721.06- [M+Cl]-. Unsure about 239.23+, 201.98-, 788.08+, and 888.05(4-). 888 possibly an adduct of nosyl chloride?

KBS50-1 RM.pdf

KBS50-1 RM.d.zip

[KlementineJBS]

06.03.24

Tried to collect precipitate by vacuum filtration but washing with cold water resulted in product dissolving. Ended up collecting small amount of solid precipitate and performing a liquid-liquid on the filtrate (3 x 40 mL DCM) to obtain a sticky yellow oil/gel.

[KlementineJBS]

Assuming that desired product can still be easily be protonated but over-nosylated product cannot. Try doing LLE with lightly basic solution e.g. Na2CO3, or manipulate at low pH to remove overnosylated product.

[KlementineJBS]

07.03.24

Tried a second extraction on the filtrate collected previously. Dissolved in chloroform (50 mL) and acidified with 50 mL HCl (0.1 M).

Aqueous layer was then basified to ~ pH 14 using NaOH (2.5 M) in the hopes of precipitating out product. Adding base seemed to result in increased dissolution of a small amount of white precipitate.

Aqueous layer was then extracted with chloroform (3 x 30 mL), dried and rotovapped.

During process, a considerable amount of white-yellow solid stuck to the sep funnel and could not easily be removed with water or organic solvent. Using acetone, this was removed and characterised separately. It did not dissolve easily in any solvent attempted except DMF.

2nd extract vial: 15.8852 mass: 5.8 mg

residue vial: 15.9801 mass: 544.9 mg

TLC analysis suggests that it contains at least one of the products (top spot) with a tiny amount of the bottom spot also present.

(E = extract, R = residue. Same solvent system as above.)

[KlementineJBS]

H NMR

Suggests that both products contain amines with some level of nosylation. Hopefully MS will shed more light.

KBS50-1 second extraction and residue.pdf

nmr300_20240307_KBS50-1 2nd extract_1.zip nmr300_20240306_KBS50-1 filtrate_10 (1).zip

[KlementineJBS]

Plans

• filter out white solid from second extraction's aqueous layer (see image)
• rotovap down chloroform layer to see contents

[KlementineJBS]

LRMS

Shows that both second extract + residue contain bis and tris nosylated amine.

Reference	Evidence of bis nosyl product	Evidence of tris-nosyl product	Other	TLC spots
second extract	500.09- [M-H]- and 502.06+ [M+H]+	685.04- [M-H]-	none	C, D, E
third extract	-	-	-	A, B, C
residue	502.05+, 500.09-	685.08- and 709.05+	none	C, E
ppt	502.04+ and 500.06-	none	539.98+, 581.19+	A, C, E

(Assume that A, top spot, is nosyl chloride)

KBS50-1 residue.pdf KBS50-1 ppt.pdf KBS50-1 second extract.pdf KBS50-1 second extract.d.zip

[KlementineJBS]

Realised that it's actually probably better to use the tris-nosyl amine as this prevents the inner amine from reacting. Previously, the nosyl group was intended to increase nucleophilicity of the terminal amines, but in a Mitsunobu reaction the internal amine can react equally well as the protected terminal amines.

[KlementineJBS]

13.03.24

Filtered out white precipitate from aqueous layer and also reduced down CHCl3 layers.

Precipitate was yellow and crystalline, and reduced chloroform extracts foamed up significantly.

Precipitate:

precipitate vial: 15.8257 mass: 150.1 mg

third extract vial: 15.8251 mass: 929.6 mg

[KlementineJBS]

TLC time

TLC'd to determine what products are in what. Noted in table above.

[KlementineJBS]

More H NMR

Still hard to determine nature of products without separation, but third extract and ppt are clearly "cleaner" than earlier attempts.

Will likely just reattempt this and try to force to completion.

KBS50-1 four products.pdf nmr300_20240313_KBS50-1 ppt_10.zip nmr300_20240313_KBS50-1 third extract_1.zip

[KlementineJBS]

Better photo of different products by TLC - used 4.5% MeOH, 0.5% NH4OH and 95% DCM.