Topicity and Conformational Analysis

Question 1

Homotopic

Answer 1

Two groups of identical constitution are homotopic if making a change to one group, then separately, the same change on the other group, results in the same structure

Question 2

Enantiotopic

Answer 2

If replacing one group, then the other results in a pair of enantiomers

Question 3

Prochiral centre

Answer 3

Atom with two heterotopic groups attached

Question 4

Diastereotopic

Answer 4

If replacing one of two identical groups leads to a pair of diastereomers

Question 5

How can enantiotopic groups/faces be distinguished?

Answer 5

They cannot be distinguished by any technique in any achiral environment

Question 6

How can diastereotopic groups/faces be distinguished?

Answer 6

Spectroscopic techniques (like NMR)

Question 7

Anomeric effect

Answer 7

Originally defined as the tendency of heteroatomic substituents (such as an OH group) adjacent to a heteroatom within a cyclohexane ring to prefer the axial orientation

heteroatom = not C or H

Question 8

Stereoselective reaction

Answer 8

A reaction which only one of a set of stereoisomers is formed exclusively/predominantly

Question 9

Stereospecific reaction

Answer 9

One stereoisomer of a starting material produces one stereoisomer of the product while another stereoisomer of the starting material gives a different stereoisomer of the product

Question 10

What does hydrogen bonding in a Newman projection lead to?

Answer 10

Stabilized gauche conformation