Question

Predict the major product(s) from the following reactions:

CH3 CH₃ H₃C H₂ ? -CH₃ CH3 НАС 1. BH3-THF 2. H2O2, NaOH ? CH3 Brz CH3 CH2OH

Answer 1

CHA H₂ | cu, H, It is the hydrogenation reaction. Herre et acts as a catalyst what occurs here that the alkene and H₂ altauns at the pt surface, So, syn addition occurs. in CH3 CH3 syn addition occurs here. om H 4 major pat » Btlg ý a 'p' orbital of newis acid with vacant boron.

At first hindered BHg attails side of the to the less double bond. CH3 CH3 BHg City • Ut3 43 H... BH₂ CH3 CH3 - Н 2 Cha CH3 (di alkyl substituted telerta alkyd substituted Boron does not form due to steric Boron pet) 43 CH3 Eat we take the CH3 as R b Me - Me on 2nd step OOH + H₂O. NOOH + H₂O2 → + H Co-o-H on BOH + H₂O. ooh out as a neucted phile and reacts

р-н = Me H-Dк R Cits HB - OTOH City 1,2 migration occurs Cita Cam си, 11 CHB он zo Bro- CH3 CH Lone. CH3 ㅐ 애 maj. belt product

CH₂ - CH2 1. B₂ Ho/THE 41 2. H₂02/one H CH3 CH OH major bat broduit g) m Brz CHOH At first the reaction goes through Cyclic bromonium intermediate. The Br dar - Co toro In the and step the competition begins between Bro and CH₂OH ie which acts as a neucleo phile е е ең оң ал аѕ a solvent and is present in a very big amount so immidiately it attacks the zo carbon of cyclic bromonium . intermediate which has greater ist character due to more electronegative

CH₂014 Br koutz -H BO L OCH ме Bral CH₂OH anti addition occurs. sebr unOCH CH3 major product