Protecting Groups

Question 1

What is a THP group?

Answer 1

(THP ethers are stable to hydrogenation, strong bases, hydrides, fluorides, oxidants - needs a mild acid to remove)

Question 2

What do you react with following alcohol with to add a THP ether protecting group?

Answer 2

React with DHP and acid catalyst

Question 3

What is the mechansim for protecting an alcohol using THP ethers

Answer 3

Question 4

How do we deprotect an alcohol from a THP ether?

Answer 4

React with 2M HCl (aq) and THF

Question 5

What do you react with the following alcohol to form a benzyl ether protecting group?

Answer 5

• React with BnBr
• Stable to: strong base, hydride, fluoride, oxidants

Question 6

How do we remove the following benzyl ether protecting group from an alcohol?

Answer 6

• Through hydrogenation or HBr/AcOH

Question 7

How would you react the following diol to add a acetonide protecting group?

Answer 7

• Stable to: hydrogenation, strong base, hydride, fluoride, oxidants

Question 8

How do we remove the acetonide protecting group from this alcohol?

Answer 8

• Mild aqueous acid

Question 9

How would you react the following diol to add a silane protecting group

Answer 9

Stable to: strong bases, hydrides, hydrogenation, oxidants

Question 10

How do we remove this silane protecting group from the alcohol?

Answer 10

Remove by: TBAF or 2M HCl

Question 11

How would we react the following ketone/aldehyde to add a dioxolane protecting group

Answer 11

Stable to: hydrogenation, strong base, hydrides, fluoride, oxidants

Question 12

How do we remove the dioxolane protecting group to reform the ketone/aldehyde

Answer 12

mild aqueous acid

Question 13

How would we react the following carboxylic acid to add a methyl protecting group?

Answer 13

Stable to: base, mild acid and F⁻

Question 14

How would we remove the methyl protecting group from the carboxylic acid

Answer 14

React with sodium hydroxide base

Question 15

How would we react the following carboxylic acid to add a benzyl protecting group?

Answer 15

Stable to base, mild acid, F⁻

Question 16

How would we remove the benzyl protecting group from the carboxylic acid?

Answer 16

React with hydrogen and palladium catalyst

Question 17

How would we react the following carboxylic acid to add a tert-butyl ester protecting group?

Answer 17

Stable to: OH⁻, Nu, H₂, NaBH₄, F⁻

Question 18

How would we remove the tert-Butyl ester protecting group from the carboxylic acid

Answer 18

Question 19

What is the mechanism for the following reaction

Answer 19

Question 20

How could we react the following amine to add a BOC carbamtes protecting group

Answer 20

Stable to: hydrogenation, strong bases, hydrides, fluoride and oxidants

Question 21

How would we remove the following BOC carbamate protecting group from a amine

Answer 21

2M HCl or TFA

Question 22

What is the mechanism for the deprotect of the amine from a BOC carbamate

Answer 22

Question 23

How could we react the following amine to add a FMOC carbamate protecting group?

Answer 23

FMOC groups are stable to hydrogenation, acid, hydrides, fluoride and oxidants

Question 24

How could we remove the following FMOC carbamate protecting group from the amine?

Answer 24

Piperidine

Question 25

What is the mechanism for removing a FMOC carbamate protecing group from an amine?

Answer 25

Question 26

How would we react an amine to add a Cbz Carbamate protecting group?

Answer 26

Stable to: strong base, hydrides, fluoride, oxidants and acids

Question 27

How would we remove a Cbz Carbamate protecting group from an amine?

Answer 27

Removed by hydrogenation or HBr/AcOH

Question 28

How would we react an amine to add a Tosylate protecting group (most protecting)

Answer 28

Stable to: strong bases, hydrides, fluoride, oxidants and acids

Question 29

How would we remove a Tosylate protecting group from an amine?

Answer 29

Na/NH₃ - strongly reducing conditions