How to determine the number of stereoisomers of a di-substituted allene, exhibiting both axial and central chirality? What are the diastereomers and enantiomeric pairs of the compound below where A are chiral groups (central chirality)? There should be 3 diastereomers and 3 enantiomeric pairs (last page).



I previously asked a question about tetra-substituted allenes.
These are the three diastereomers with their enantiomers on the right side. The top and middle diastereomers are connected via axial chirality (R and S are used to mark the configuration of A groups).