Boron tribromide → HCID 23442243, compound

Participants

Reaction Steps

To a solution of 65 (0.8 mmol) in toluene (8 ml) was added PCl5 (4.8 mmol). After stirring the mixture for 2 hours at 20° C. it was poured into ice water and extracted with toluene. The organic layer was washed with NaHCO3 (aq), dried over MgSO4 and concentrated. The residue was dissolved in 12 ml m-xylene/toluene (2:1) palladium on carbon (10% w/w, 200 mg) was added and the mixture was refluxed for 2 hours. The catalyst was filtered off and the filtrate was concentrated. Chromatography (heptane/ethyl acetate) gave pure 2,8-dimethoxy-10-chloro-11H-benzo[b]fluorene 66a in 92% yield. (Rf=0.58 heptane/toluene (1:1)) BBr3 (3.5 mmol) was added to a solution of 66a (1.18 mmol) in 30 ml CH2Cl2 and after 1 hour another 2.1 mmol of BBr3 was added. After 1.5 hours the mixture was carefully poured into sat. NaHCO3 (aq) and extracted with ethyl acetate. The organic layer was dried over MgSO4 and concentrated. Purification on silica (toluene/ethyl acetate) afforded pure 67a in 87% yield. (Rf=0.38 toluene/ethyl acetate (4:1)); ESI-MS: M+H=283.0, M−H=281.2.

Provenance & Evidence