Benzoxazole → methoxy-benzoxazole

Participants

Reaction Steps

In Scheme VIII, bromo-benzoxazole 35 (R═CH3) was first treated with copper(I) cyanide in DMF to produce the corresponding aryl-nitrile, which upon treatment with boron tribromide afforded benzoxazole 36. Benzoxazole 36 was also prepared from a second synthetic Route, where the bromo-benzoxazole 35 was treated with zinc cyanide in the presence of a palladium catalyst [i.e. tetrakis(triphenylphosphine)palladium(0)] to afford the corresponding aryl-nitrile, which upon demethylation with boron tribromide produced benzoxazole 36. Benzoxazole 35 (R═H) was treated with copper (I) bromide, and freshly prepared sodium methoxide in DMF to produce methoxy-benzoxazole 37. Bromination of 37 with N-bromosuccinimide in acetonitrile afforded the monobromo benzoxazole 38 (major product) and the dibromobenzoxazole 39 (minor product).

Provenance & Evidence