KBS53-2 - Nosyl deprotection of KBS48

[KlementineJBS]

Link to HIRAC and master page #186

KBS44 Nosyl deprotection of linear amines.docx

Reaction scheme

Outcome

[KlementineJBS]

19.04.24

Followed protocol as in #190

Amounts:
KBS48 - 92.4 mg, 0.103 mmol
thiol (2,2 -(Ethylenedioxy)diethanethiol) - 0.411 mmol, 67 uL
potassium carbonate - 0.821 mmol, 117.5 mg

Left heating at 80 C from 9 am.

[KlementineJBS]

22.04.24

TLC indicated consumption of SM even though two products were evident.

Worked up with ethyl acetate this time.

1. Diluted with 20 mL EtOAc
2. Washed with LiCl solution (3 x 20 mL)
3. Washed with Na2CO3 solution
4. Washed with brine

Ended up reextracting the combined LiCl washes as well (2 x 20 mL EtOAc, then washed with LiCl 2 x 20 mL and Na2CO3 solution).

1st extract
vial: 15.6334
mass: 121.6 mg - quite wet

2nd extract
vial: 15.7816

[KlementineJBS]

LRMS

Signs of both singly and doubly deprotected product.

Singly deprotected: 742.20- [M-H]-
Doubly deprotected: 531.26+, 553.33+, 562.15- (unsure what adduct this is?)

KBS53-2 cr.d.zip
KBS53-2 cr.pdf

[KlementineJBS]

Column conditions

Results

Fractions	Vial tare (g)	Mass (mg)	Substance
11-14			thiol byproduct
17-20
21-39	15.7827	9.9	singly deprotected
40-52	15.7319	23.8	mixture
53-55	15.6509		doubly deprotected - product

[KlementineJBS]

24.04.24

Turns out that "double spot" in fractions 40-52 was largely a trick of the eye -- NMR indicates it is quite cleanly bis product. Suggests that second thiol is indeed more effective.

Will combine 56-59 with 40-52 after confirming by TLC and purify via prep HPLC or other methods.

[KlementineJBS]

H NMR

KBS53-2a fractions.pdf

nmr300_20240424_KBS53-2 F21-39_1.zip
nmr300_20240424_KBS53-2 F40-52_1.zip
nmr300_20240423_KBS53-2 F11-14_1.zip
nmr300_20240423_KBS53-2 F56-59_1.zip

[KlementineJBS]

HPLC (LRMS)

Note that F8 injection was probably contaminated by KBS44.

F6: No sign of any expected peaks except product. 936+, 515- and 521- are unclear.
F7: Same as above. Unidentified peaks include 615-, 791+.
F8: Tiny amount of 531+ product present. Mostly overpowered by previous injection.

KBS prep fractions 09-08-24 F8 retry.pdf
KBS prep fractions 09-08-24 F7.pdf
KBS prep fractions 09-08-24 F6.pdf
KBS prep fractions 09-08-24 F2.d.zip

[KlementineJBS]

Tried F8 again. Seems to contain largely 559+ i.e. product of KBS44. Could be due to some kind of contamination from other samples. However, separation seems good so maybe not a big problem??

There is some trace of 531+ product.

KBS prep F8 take 3.pdf
KBS prep F8 take 3.d.zip

[KlementineJBS]

LRMS of second prep HPLC

F14/15 contains 531, 928 (KBS53 product, KBS44 SM)
F15/16 contains 531 (KBS53 product) and nothing else

prep HPLCchecks.d.zip
prep HPLC F15 or 16.pdf
prep HPLC F14 or 15.pdf