Boron tribromide → Emd638683

Participants

Reaction Steps

70.0 g of N′-[2-(3,5-difluorophenyl)-2-hydroxyacetyl]-2-ethyl-4-methoxy-3-methylbenzohydrazide (A1) are suspended in 350 ml of dichloromethane. 105 ml of boron tribromide are then added dropwise. The reaction mixture is stirred at room temperature for 3 hours. The resultant solution is subsequently carefully decanted into one litre of ice-water. The aqueous phase is extracted twice with 500 ml of ethyl acetate. The combined organic phases are then extracted once with 300 ml of water, dried over sodium sulfate and subsequently filtered. The filtrate is concentrated in vacuo. The resultant residue is, then recrystallised from 500 ml of acetonitrile using activated carbon, giving 32.2 g of the title compound as colourless solid having a melting point of 187.4° C. (MS: 365 (MH+), TLC: Rf=0.29 (cyclohexane/methyl tert-butyl ether 1:4, parts by volume).

Provenance & Evidence