Asymmetric Synthesis

Question 1

How do you calculate enantiomeric excess from the molar ratios of two enantiomers?

Answer 1

Question 2

How do you calculate the molar ratios of two enantiomers from the enantiomeric excess?

Answer 2

Question 3

Draw the transitionstate when a carbonyl containing compound reacts with R-CBS and BH₃

Answer 3

Question 4

Write down the mnemonic for R-CBS

Answer 4

Question 5

What controls the face of epoxation when using m-CPBA?

Answer 5

Attacks from the least hindered site unless directed by hydrogen bonding

Question 6

Which side does (+/-)-tartrate add the epoxide to?

Answer 6

(-)-tartrate - top face

(+)-tartrate - bottom face

Question 7

Draw the mnemonic for sharpless epoxidation

Answer 7

Question 8

Draw the transition state for sharpless epoxidation

Answer 8

Question 9

Write down the mnemonic for salen molecules

Answer 9

Question 10

if you have 2-cyclohexenol and you want to Hydroxylate it with OsO₄ how do you control which face is added to and why?

Answer 10

TMEDA adds e^- density allowing for hydrogen bonding and dihydroxilating the same face.

Otherwise sterics will cause it to happen on the least hindered face

Question 11

Write down the mnemonic for AD mixes

Answer 11

Question 12

When the stereochemistry for an enolate to form an aldol is controled with a metal, what do the transition states look like and how does it effect the product?

Answer 12