Electrophilic bromination of pyrroles bearing carbonyl substituents at C-2 typically results in a mixture of the 4- and 5-brominated species, generally favoring the 4-position. Herein, we describe a substrate-controlled regioselective bromination in which tetra-butyl ammonium tribromide (TBABr) reacts with pyrrole-2-carboxamide substrates to yield the 5-brominated species as the predominant (up to >10:1) product.

The hydroxyamination reagent Br-N-(CO2Me)2 underwent Markovnikov addition to various olefins in the presence of catalytic BF3·OEt2 and provides efficient access to aminoalcohols. The reaction provided the trans-1-bromo, 2-N-bis-carbamate adduct stereoisomer in all cases. The resulting adduct underwent cyclization to give an oxazolidinone, which could be readily hydrolyzed to an oxazolidin-2-one or an amino alcohol.

KUSZPIT, M. R.; GILETTO, M. B.; JONES, C. L.; BETHEL, T. K.; TEPE*, J. J.; J. Org. Chem. 80 (2015) 3, 1440-1445, http://dx.doi.org/10.1021/jo502369d ; Dep. Chem., Mich. State Univ., East Lansing, MI 48824, USA; Eng.) -H. Hoennerscheid 26-163