KBS29-6 - Bromination of KBS28 with phosphorus tribromide

[KlementineJBS]

Link to HIRAC and master page. Method taken from J. Batten's PhD thesis (2022).

KBS29 - Appel reaction (CBr4).docx

Previous attempt is #154

Reaction scheme

Outcome

353 mg (1.23 mmol, 35%)

[KlementineJBS]

13.11.2023

1. Used all product from #153 (784 mg, 3.48 mmol) and added 1 equiv. of PBr3 (0.3 mL, 3.48 mmol)
2. Stirred for ~ 2 hours. TLC indicated completion.

60% EA in hexanes

[KlementineJBS]

14.11.23

Quenched with NaHCO3 (20 mL), diluted with water and worked up with DCM (3 x 50 mL), then washed with water (60 mL) and brine (50 mL). Lots of reddish solid has formed overnight - solid was water soluble.

empty vial: 15.7355 full vial: 16.5560 mass: 822.5 mg, 2.85 mmol, 82%

[KlementineJBS]

H NMR

Looks good. A little DCM left - will hi vac and recalculate yield.

KBS29-6 cr.pdf KBS29-6 cr_1.zip

[KlementineJBS]

New yield

(after hivac)

full vial: 16.5003 mass: 765 mg, 2.65 mol, 76%

H NMR

Also NMR'd dark red water soluble material (called SP). Didn't dissolve very well in chloroform but appears to be product.

In any case, product will have to be purified before moving on.

KBS29-6 SP_1.zip KBS29-6 repeat_1.zip KBS29-6 repeat NMR.pdf

[KlementineJBS]

Columm

Columned and got a hugely reduced yield. Need to check if a column flush helps. Product nice and clean now though with mystery peak at 4.63.

KBS29-6 clean_1.zip KBS29-6 clean.pdf

New yield: 353 mg (1.23 mmol, 35%)

[KlementineJBS]

Product is a crystalline, yellow-gold powder.