Handout 1 Material

Question 1

Is halohydrin addition syn or anti?

Answer 1

anti addition

Question 2

Is hydrogenation syn or anti

Answer 2

syn addition

Question 3

What are reagents for oxymercuration?

Answer 3

Hg(OAc)2 and NaBH4 for reduction

Question 4

Is there an intermediate in oxymercuration and is the addition to the intermediate syn or anti?

Answer 4

Yes and it is anti

Question 5

What are reagents for hydroboration?

Answer 5

BH3THF and then NaOH and H2O2

Question 6

What are some advantages of 9-BBN

Answer 6

doesn’t react with carbonyls, air stable, stops after one addition, can be more regioselective

Question 7

What do you use for dihydroxylation? And what is an associated problem?

Answer 7

OsO4 (osmium tetroxide) and it has associated toxicity.

Question 8

What is upjohn modification?

Answer 8

Use NMO (n-methyl-morpholine N-oxide) to reoxidise osmium

Question 9

Reagents for ozonlysis

Answer 9

O3/Me2S or can use PPh3

Question 10

What happens during ozonlysis?

Answer 10

Break C=C make 2 new C=O

Question 11

What 3 steps happen in ozonolysis of alkenes?

Answer 11

1,3-DP, then 1,3-retro DP, then 1,3-DP again (where 1,3-DP is 1,3-dipolar cycloaddition)

Question 12

What do we use for epoxidation of alkenes?

Answer 12

MCPBA

Question 13

Why is there no trans epoxide

Answer 13

C-O bond formation is concerted

Question 14

Why do electron rich alkenes react the fastest?

Answer 14

reaction involves pi electron cloud attacking delta+ oxygen. R groups donate e- density.

Question 15

Reagents for epoxide ring opening?

Answer 15

Nucleophile. Base common or NH2. Could use gringard also

Question 16

How do you reduce an epoxide?

Answer 16

LiAlH4 or LiH3 works

Question 17

Which nucleophile would you use in epoxide ring opening to generate salbutamol (anti-asthma drug)

Answer 17

an amine

Question 18

How do you generate Z (cis) alkene?

Answer 18

Lindlar’s catalyst

Question 19

How do you generate E (trans) alkene?

Answer 19

Dissolved metal reduction (example is NaNH3 and tBuOH)

Question 20

Reagents for oxymercuration of alkynes?

Answer 20

Hg(OAc)2

Question 21

What happens to final product of oxymercuration?

Answer 21

Tautomerises to a ketone

Question 22

How does E alkene reaction from alkyne proceed?

Answer 22

Via sodium radicals

Question 23

What isomer of alkene do you get from hydroboration of alkynes?

Answer 23

Trans isomer

Question 24

Does hydroboration of alkyne stop at alkene?

Answer 24

No can go further to alkane

Question 25

What happens when you use 9-BBN for hydroboration of alkynes?

Answer 25

Get one addition. I.e- get trans isomer.

Question 26

How do you generate an alkyne anion?

Answer 26

NH3/NaNH2

Question 27

Explain acidity of H atoms in terms of hybridisation

Answer 27

sp3