KBS49-2 - Mitsunobu reaction with KBS28 and KBS45

[KlementineJBS]

Link to HIRAC and master page #174.

HIRAC KBS48 Mitsunobu reaction on linear amines.docx

Reaction scheme

Outcome

[KlementineJBS]

19.02.24

1. Added SM amine KBS45 (202 mg, 0.393 mmol), PPh3 (364.3 mg, 1.389 mmol, 3.5 equiv.) and SM KBS28 (228.8 mg, 1.016 mmol, 2.6 equiv.) to a dry flask
2. Evacuted + backfilled with N2 x 5
3. Added solvent (4 mL dry THF, 4 mL dry toluene)
4. Cooled to 0 C
5. Added DIAD (0.27 mL, 1.362 mmol, 3.5 equiv.)
6. Left stirring from 4 pm

[KlementineJBS]

20.02.24

TLC at ~ 1.30 pm. Amine appears to be consumed but also didn't show up well in SM so could be due to TLC technique. Decided to run mass spec to check.

Eluent is 0.5:4.5:95 NH4OH:MeOH:DCM

[KlementineJBS]

LRMS of RM

KBS49-2 RM.d.zip
KBS49-2 RM.pdf

Evidence of SM (513.11- [M-H]-), mono product (720.25- [M-H]-) and lots of PPh3O adducts (579+, 856(+2), 1133(+3). The same mass that was taken as evidence of bis product in #183, 951.31+, here shows up as 951.27 but with a 3+ charge - this suggests it is not in fact the bis product.

Took another spectrum ~5 hours later

KBS49-2 RM later 20-02-24.pdf
KBS49-2 RM later 20-02-24.d.zip

[KlementineJBS]

20.02.24

Confused by this TLC as had thought that top spot of left plate was bis product, but this seems to have disappeared/reverted to mono in the later TLC (right), taken ~5.30 pm. Decided to do MS to check.

LRMS

KBS49-2 RM later 20-02-24.pdf
KBS49-2 RM later 20-02-24.d.zip

Same as previously except new peak at 963.35- could represent [M+Cl]- for the bis compound, and 743.24+ is probably [M+Na]+ for mono compound.

[KlementineJBS]

21.02.24

Final TLC was still confusing.

Worked up anyway.

7. Evaporated solvent under reduced pressure
8. Triturated with ice cold diethyl ether (5 x 3 mL)
9. Evaporated solvent again

vial weight: 15.7422
mass: 628.8 mg (0.677 mmol, well over 100%)

[KlementineJBS]

LRMS of crude product

Evidence of bis product (951+), as well as SM (513-), mono (720-) and lots of PPh3O.

KBS49-2 cr.d.zip
KBS49-2 cr.pdf

[KlementineJBS]

H NMR

Seems to not have gone as cleanly as #183 and has obvious evidence of mono product, but seems that majority is still bis product. Will column soon.

nmr300_20240221_KBS49-2 cr_1.zip
KBS49-2 cr.pdf

[KlementineJBS]

Column

Pooled fractions 3-6. F1-2 assumed to be DIAD - positive result with vanillin.

nmr300_20240223_KBS49-2 F3-6_1.zip
KBS49-2 F3-6.pdf

Again pretty clean except for DIAD!

[KlementineJBS]

LRMS

KBS49-2 F3-6.pdf
KBS49-2 F3-6.d.zip

[KlementineJBS]

Some relevant TLC plates

[KlementineJBS]

Column conditions

Advice from the internet suggested using DCM/acetone to remove DIAD. 5% acetone in DCM seems to offer the best separation, assuming that product is the white spot below DIAD. (Stained with vanillin)

[KlementineJBS]

Column b

Fractions	Spots	Vial tare (g)	Mass (mg)	NMR evidence	LRMS evidence
1	A	15.8859		Fairly large amount of mono (?), no DIAD	SM at 513.09-
2-6	ABC	15.9178	280.5	almost no DIAD, mix of bis and mono	SM at 513.10-, mono at 720.25- and 744.11+and bis at 963.32- and 951.25+, also 313.16+, 603.15+
7-11	BC	15.9576	33.9	Bis, small amount of DIAD and mono	313.11+, didn't dissolve well
12-20	CD	15.7448	20.0	Bis, larger amount of DIAD, small amount of mono	bis at 951.16+ and 963.27- but also 227.12+ (likely DIAD hydrazine), 313.12+, 603.20+, 773.32+
21-22	unclear
28-35	E	16.1142	12.4	tiny amount of product, mostly DIAD
36-53	E	15.8146	20.5	unclear, maybe just DIAD?

Seems that the first three spots ABC are mono (A) and bis (C) with some DIAD SM remaining (B). Hydrazine appears to be D/E.

Unreacted DIAD should be easier to remove than the hydrazine but this solvent system doesn't work for it.

[KlementineJBS]

H NMR

KBS49-2b fractions.pdf

nmr300_20240305_KBS49-2b F28-35_1.zip
nmr300_20240305_KBS49-2b F7-11_1.zip
nmr300_20240305_KBS49-2b F12-20_1.zip
nmr300_20240304_KBS49-2b F1_1.zip
nmr300_20240304_KBS49-2b F36-53_1.zip

[KlementineJBS]

LRMS

KBS49-2b F1.pdf
KBS49-2b F2-6.pdf
KBS49-2b F7-11.pdf
KBS49-2b F12-20.pdf

KBS49-2b Fractions.d.zip

[KlementineJBS]

Yet another column

Considered some more column eluents. Ended up selecting 2.5% MeCN in DCM.

Ran column on F2-6 from previous attempt and got good separation of spots.

Results

Fractions	Spots	Vial tare (g)	Mass (mg)	substance
2-13	15.9051	19.1	unsure - DIAD adduct of bis product?
14-15	15.9252	3.2	mono, presumably SM
16-60	16.0097	mono, some DIAD still
61-74	15.7864	3.2	mono and bis
75-120	16.1755	bis

[KlementineJBS]

LRMS

Identity of pure mono and bis fractions was confirmed by MS analysis.

bis product
951.35+ [M+Na]+
963.25- [M+Cl]- with typical Cl isotope pattern

mono product
744.14+ [M+Na]+
720.20- [M-H]-
Some unknowns remain: 603.18+, 313.16+

KBS49-2c F16-60.pdf
KBS49-2c F75-120.pdf
KBS49-2c F75-120.d.zip

[KlementineJBS]

H NMR

KBS49-2c fractions.pdf

nmr300_20240312_KBS49-2c F16-60_1.zip
nmr300_20240312_KBS49-2c bis_1.zip
nmr300_20240312_KBS49-2c F14-15_1.zip
nmr300_20240312_KBS49-2c F61-74_1.zip
nmr300_20240311_KBS49-2c F75-120_1.zip
nmr300_20240311_KBS49-2c F2-13_1.zip