A Facile and Highly Regioselective Conversion of Epoxides to Bromohydrins Using Tetrabutylammonium Bromide and Magnesium Nitrate

Abstract

Reaction of epoxides with nBu4NBr in the presence of Mg(NO3)2 as a catalyst affords vicinal bromohydrins in excellent yields via regioselective ring opening of the unsymmetrical epoxides.

Organic halides

“…A general and regioselective conversion of epoxides into 1,2-bromohydrins has been developed using tetrabutylammonium bromide and magnesium nitrate (Scheme 1 24). 239 The very high regioselectivity of this particular process is underlined by the observation that styrene oxide (R = Ph), which under most conditions affords the secondary halide (not shown) by nucleophilic attack at the benzylic position, gives the primary halide preferentially (83 : 17 mixture).…”

Tetrabutylammonium Bromide

“…The use of TBAB as a source of the bromide anion allows the regioselective ring opening of epoxides to bromohydrins at room temperature when magnesium(II) nitrate is used as catalyst, the bromide attack taking place at the lesshindered position of the epoxide (eq 14). 76 This type of TBABpromoted epoxide ring opening gives rise to five-membered cyclic orthoesters when performed in the presence of perfluorocarboxylates. 77 Cyclic sulfates from chiral 2,3-diol esters can also be regioselectively ring opened to bromohydrins for the synthesis of chiral α,β-epoxy esters.…”

Methimazole-disulfide as an Anti-Thyroid Drug Metabolite Catalyzed the Highly Regioselective Conversion of Epoxides to Halohydrins with Elemental Halogens

“…The crude was purified by chromatography on a column of silica gel. The halohy drins obtained throughout this procedure were identified by comparison with authentic samples prepared according to literature procedures.9,10, [19][20][21][22][23][24] The product has been reported before but 1H-NMR spectral data were not given.…”