Chapter 6.4: Hydroboration-Oxidation

Question 1

Describe the mechanism behind hydroboration-oxidation of an alkene

Answer 1

• Hydroboration:
o Step 1: Lewis Acid-Base Coordination
 The addition of borane to an alkene is initiated by coordination of the vacant 2p orbital of boron with the electron pair of the pi bond
o Step 2: Make a new bond between a nucleophile (pi bond) and an electrophile with simultaneous bond formation to H
• Oxidation of Trialkyborane by Alkaline Hydrogen Peroxide
o Step 1: Make a new bond between a nucleophile and an electrophile
o Step 2: 1,2 shift
o Step 3: Reaction of the trialkylborate with aqueous NaOH gives the alcohol and sodium borate

Question 2

Define syn stereoselctive

Answer 2

the addition of atoms or groups of atoms to the same face of a carbon-carbon double bond

Question 3

What is a method for converting an alkene to an alcohol. The alkene is treated with borane (BH3) to give a trialkylborane, which is then oxidized with alkaline hydrogen peroxide to give an alcohol?

Answer 3

hydroboration-oxidation

Question 4

Define hydroboration-oxidation

Answer 4

a method for converting an alkene to an alcohol. The alkene is treated with borane (BH3) to give a trialkylborane, which is then oxidized with alkaline hydrogen peroxide to give an alcohol

Question 5

What is the addition of atoms or groups of atoms to the same face of a carbon-carbon double bond?

Answer 5

syn stereoselective

Question 6

What is the stereochemistry of hydroboration-oxidation?

Answer 6

syn

Question 7

What is the regiochemistry of hydroboration-oxidation?

Answer 7

Non-Markovnikov