Merging the ring opening of benzoxazoles with secondary amines and an iron-catalyzed oxidative cyclization towards the environmentally friendly synthesis of 2-aminobenzoxazoles
A facile and environmentally friendly method was developed through merging the ring opening of benzoxazoles with secondary amines and an iron-catalyzed oxidative cyclization towards the synthesis of 2-aminobenzoxazoles. In the oxidative cyclization step, with catalytic amounts of FeCl and aqueous H 2O2 as a green oxidant, highly desirable 2-aminobenzoxazoles were isolated in excellent yields of up to 97%. A plausible radical process is proposed for the oxidative cyclization on the basis of mechanistic studies.
A metal-free route to 2-aminooxazoles by taking advantage of the unique ring opening of benzoxazoles and oxadiazoles with secondary amines
Toss an amine into the ring: A new metal-free protocol for the amination of oxazoles has been developed by using iodobenzene diacetate to couple various oxazoles with amines (see scheme). The reaction proceeds through a ring-opening and subsequent ring-closing pathway. The optimal conditions are very mild and the substrate scope is broad, producing a range of 2-aminooxazoles, an important pharmacophore with high bioactivity. Copyright
Joseph, Jomy,Kim, Ji Young,Chang, Sukbok
supporting information; experimental part
p. 8294 - 8298
(2011/08/21)
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