Question

1. Find the product from the following reaction sequence: 1. (C6H5)3P-CH2 2. BHz,THF 3. H2O2, HO

Answer 1

Major product is 2-cyclohexylethan-1-ol

First reaction is the wittig reaction in which oxygen of Carbonyl group of aldehyde replace by CH2 group of wittig reagent. So 2-cyclohexyleth-2-ene formed after first reaction.

Second and Third reaction combine called hydroboration oxidation reaction. In which double bond reduce and alcohol formed according to anti markovnikov rule.In which hydrogen add to less hydrogen site and OH group to more hydrogen site.

This is because BH3 add to less substituted site and the H2O2 in basic medium is use for oxidation so OH replace BH2 group. Hence 2-cyclohexylethan-1-ol formed as final product.

OH 1) (C6Hs J , P - CH₂ 2) BHE.THE 3) H2O2. OH Mechanism :- CH₂ BH₂ C6Hs), P-CH B H₃. THE H₂O2,OH- OH