Question

(a) The bromohydrins produced by exposure of cis-2-butene to bromine water have two chirality centers and no symmetry, so can exist as four configurational isomers (RR, SS, RS, and SR). Just two of these four possible isomers (the enantiomeric RR/SS pair) are in fact produced, as shown below: н, „Н Вг, в н н Во C-C...H CH, H2OH-S3 + HCA - Ho's s cH, HE R ROH Write a curved arrow mechanism, including a cyclic bromonium ion intermediate, that accounts for the formation of only the two indicated configurational isomers. (b) On treatment with aqueous bromine, the alkene shown below affords a cyclic bromo ether rather than a bromohydrin. Write a curved arrow mechanism to account for the indicated product. H, C = CH(CH-], OH - CH₂ Br Che Br 8.3

Answer 1

Br Br aetta roor Ho 06 Club CH3 WS Hoö m unit Selts Br-Br 20- Et (42C Ho- we o