Some articles on diastereotopic:

Topicity - Diastereotopic
... The stereochemical term diastereotopic refers to the relationship between two groups in a molecule which, if replaced, would generate compounds that are diastereomers ... Diastereotopic groups are often, but not always, identical groups attached to the same atom in a molecule containing at least one chiral center ... of the CH2 moiety in (S)-2-bromobutane are diastereotopic ...