Question

9 pts). Circle the expected major PRODUCT for each of the following sequence of reactions. 1) BH 2) HO PCC OL Hc A dation PRODUCT CH, HOS CH H, CH он 1 BUNA Hạ – =C=CH- BC PRODUCT er CH, . CH H. " ci H. нс нас" Br/ BB BC ang fra H cocitts HỌC-C=c- NaNH, A 5 , B HO, PRODUCT CH - C HAC-C=C H,C-C=C- LOH он он OM Hic OH нсс сн,

please explain in details why each one of these is the right answer?

Answer 1

CH3 1. BH3 2. H202 CH3 CH3 PCC oxidation Hz OH HzCY CH3 H, со CH3 CH3 Alkene on hydroboration followed by oxidation reaction give alcohol product as shown above. Since borane is a hydride ion transfer agent, the hydroxyl group add on to the alkene with less number of carbons. Pyridiniumchlorochromate (PCC) oxidation of alcohol give corresponding ketone as shown above. CI 1 eq. Cl2 Br2 Br, CI H3CCH3 CIBr Both chlorine and bromine add on to the double bonds via trans manner with the cyclic halonium ion intermediates. Hence reaction of alkyne with one equivalent of Cl2 give trans dichloro alkene which on reaction with bromine give all trans product. NaNH2 H3C - H - 18. H2O Na -OH Na 2. H20 Terminal alkyne on reaction with sodamide give sodium alkynlide. Epoxide opens from the less substituted carbon side in basic medium to give product B which on aqueous workup give final product as shown above.