What I need to detect if .net framework 4.5.X is installed on the current OS?.
I tried this but seems to be limited to framework 4.0 using a non-official update.
Just did your googling for you and found the following MSDN article directly referring to your question. Includes examples for version 4.5 and later...
https://msdn.microsoft.com/en-us/library/hh925568(v=vs.110).aspx