dolphin133

Thank you very much for your reply. I really understood and is much clear now. Is nice to have people like you who keep forums like this going forward. 

Hi, thank you for the answer. What you say is true, it can be pointing backwards.

I don't understand good the example a) why it is R configuration?

and if someone can explain me in detail little how this works i would be grateful.

Can someone please help me with understanding how this works?

I undestand a bit, but don't get why for example the     a)   is  a  "R" configuration?
and not an S, because I think that "COCH3"  is first then "HO"  is second and third "CH3"
So this in my logic should be S.

Can someone help me understand why is "HO" first?

If you want to comment also the other ones, please feel free, it will help me understand faster.
I have the result, just I don't understand WHY.

I will be very grateful to whom would like to comment and help me with this.

Thank You guy for your time and your help.