JEE Advanced levelSingle correct optionDifficulty 3 of 3o2200
3-Methylbut-1-ene is treated with HBr (no peroxide) to give A. A is heated with alcoholic KOH (Zaitsev elimination) to give B. B is treated with BHX3⋅THF and then HX2OX2/NaOH to give C. C is
A3-methylbutan-2-ol
B3-methylbutan-1-ol
C2-methylbutan-2-ol
D2-methylbutan-1-ol
Answer: A
A is 2-bromo-2-methylbutane, formed after a hydride shift. Zaitsev elimination gives B, 2-methylbut-2-ene. Hydroboration puts boron on the less substituted carbon C3, so C is (CHX3)X2CH−CH(OH)CHX3, 3-methylbutan-2-ol.