KBS48-2 - Mitsunobu reaction with KBS28 and KBS43

[KlementineJBS]

Link to HIRAC and master page #174.

HIRAC KBS48 Mitsunobu reaction on linear amines.docx

Reaction scheme

Outcome

only 86.4 mg purified completely - 0.0960 mmol, 23% approx. the same mass again was purified but still contains DIAD golden solid purified for use here was ~138.9 mg (0.154 mmol, 37%) some of this purified separately in #194

[KlementineJBS]

28.02.24

1. Added KBS43-3 (204.7 mg, 0.421 mmol), KBS28 (228.9 mg, 1.02 mmol, 2.4 equiv.) and PPh3 (243 mg, 0.926 mmol, 2.2 equiv.) to a dry flask
2. Added dry THF (3 mL) and dry toluene (3 mL)
3. Cooled to 0 C for 15 minutes
4. Added DIAD (0.18 mL, 0.917 mmol, 2.2 equiv.)
5. Left stirring from 3 pm

[KlementineJBS]

29.02.24

TLC indicated reaction was not complete, so heated to 45 C and left from 12.

Increased heating to 60 C from 3pm

[KlementineJBS]

01.03.24

Turned off reaction at 6 pm and left over the weekend (stoppered).

[KlementineJBS]

04.03.24

TLC indicated only a small amount of SM remaining, so worked up.

Removed solvent via rotary evaporation and triturated with cold ether, 5 x 3 mL.

Vial: 15.7600 mass: 736.1 mg (0.818 mmol, way over 100%)

[KlementineJBS]

H NMR

Looks reasonably clean, with DIAD as usual, and a small amount of mono product evident.

nmr300_20240304_KBS48-2 cr_1.zip KBS48-2 cr.pdf

[KlementineJBS]

LRMS

Evidence of SM at 484.99- [M-H]-, PPh3O adducts and product at 935.30- [M+Cl]-. Also has 975.28- and 301.10+, which maybe corresponds to 313 in KBS49 ?

KBS48-2 cr.pdf KBS48-2 cr.d.zip

[KlementineJBS]

Column conditions

Will attempt a silica plug and then a column. Unsure whether to try silica plug with 5% acetone in DCM or straight DCM?

[KlementineJBS]

Silica plug

Used about 7 cm silica in a 3 cm diameter sintered funnel. Loaded sample with DCM then washed with 1% acetone in DCM (~150 mL) until lower band separated out. (See lower band in picture below.)

Washed with 10% acetone in DCM (100 mL) and then 10% MeOH in DCM (100 mL) -- separated last 50 mL as could see a separate band was left.

plug 1 vial: 15.9932 mass: 443.2 mg

plug 2 vial: 16.1718 mass: 337 mg

[KlementineJBS]

H NMR

DIAD still remains, but hopefully this is the DIAD hydrazine that was expected to remain.

Interestingly, plug 1 (which was washed through first) appears to contain more bis product, and plug 2 appears to contain more mono product. It's definitely possible that a labelling mistake was made, though.

nmr300_20240318_KBS48-2 plug 1_1.zip nmr300_20240318_KBS48-2 plug 2_1.zip KBS48-2 silica plug.pdf

Need to TLC to check presence of DIAD/DIAD hydrazine.

[KlementineJBS]

Column conditions

Fractions	vial (g)	mass (mg)	Substance
1-17	16.		bis product, with unknown peak at 3.76 + lots of DIAD
18-27	15.9770	17.4	bis product, with unknown peak at 3.76 + lots of DIAD

[KlementineJBS]

Was columning for the wrong peaks this whole time.

Thankfully, fractions 1-27 are quite clean bis product. Need to figure out what this peak at 3.76 is before carrying on.

Plug 1 also contains largely bis, with ~15% of mono. Will column this next.

[KlementineJBS]

Column conditions

Fractions	vial (g)	mass (mg)	Substance
1-35	16.1375	17.2	bis
36-49	16.1923	8.9	bis
50-94	16.0243	60.3	bis
95-110	15.9441	69.7	bis, some hydrazine
111-136	16.3669	32.0	bis, some DIAD hydrazine

[KlementineJBS]

LRMS

Signs of bis product in both.

F1-35: 923.26+ [M+Na]+, 935.25- [M+Cl]-, 975.08-

F111-136: 923.18+ [M+Na]+, 975.29-

KBS48-2b F111-136.pdf KBS48-2b F1-35.pdf KBS48-2b.d.zip

[KlementineJBS]

H NMR

KBS48-2b fractions.pdf

KBS48-2b F95-110_1.zip KBS48-2b F35-49_1.zip KBS48-2b F111-136_1.zip KBS48-2b F50-94_1.zip KBS48-2b F1-35_1.zip

[KlementineJBS]

26.03.24

Pooled fractions 36-110 and put under hi vac to get more accurate mass before carrying through to denosylation step. Kept aside small amount for characterisation later.

Pooled fractions dried into an attractive golden foam during rotovapping/hi vac process.