Chapter 6: 6.3 Hydroboration

Question 1

List:

Characteristics of Hydroboration/Oxidation reactions

Answer 1

1. Occur multiple steps
2. Have anti-Markovnikov addition for a regiochemical outcome
3. The addition of the OH and H groups is syn for the stereochemical outcome

Question 2

Describe:

Anti-Markovnikov addition

Answer 2

Has the higher priority group added to the less substituted carbon atom

Question 3

What does “syn” mean?

Answer 3

On the same side

Question 4

What is Borane? What does it exist in nature as?

Answer 4

Borane is BH3
* Exists in nature as a dimer (B2H6)

Question 5

How will you see Borane in this course?

Answer 5

• BH3THF
• BH3Me2S

Question 6

Why are borane species different in this course?

Answer 6

These are reactive borane species from Lewis acid (boron)/Lewis base (oxygen or sulfur) interactions

Question 7

List:

Steps of Hydroboration/oxidation reactions

Answer 7

1. Syn addition of the B-H bond across the alkene via a four-membered ring transition state
2. Oxidation of the B-C bond to form the OH group

Question 8

What can hydroboration/oxidation reactions be used to produce from terminal alkynes?

Answer 8

Aldehydes