H-β-zeolite catalyzed synthesis of β-bromostyrenes from styrene bromohydrins

A stereoselective synthesis of (E)- or (Z)-β-arylvinyl halides via a borylative coupling/halodeborylation protocol

“…The purity of all obtained products were confirmed by GC-MS and 1 H NMR and the results were in agreement with the literature. 15,16,35 (E)-β-Bromostyrene (1a). 35…”

“…13 Other effective methods leading to (E)-alkenyl halides are based on the catalytic anti-Markovnikov hydrobromination of alkynes, which occurs via the hydrocupration of alkynes, followed by bromination of the alkenyl copper intermediate, 14 homologation and further stereoselective elimination of benzyl bromides with dihalomethanes in the presence of a base 15 or intramolecular dehydration of bromohydrins using H-β zeolite as a catalyst. 16 (Z)-β-Arylvinyl bromides can be synthesized by the Wittig olefination of an aldehyde with bromomethylene triphenylphosphorane, 17,18 by the reaction of aromatic aldehydes with α-bromomethyl sulfones (Julia olefination), 19 Pdcatalyzed debromination of 1,1-dibromo-1-alkenes by tributyltin hydride 20,21 or debrominative decarboxylation of anti-2,3-dibromo-3-arylpropanoic acids using e.g. NaN 3 .…”