how to assing property with the name to a expando object ?

i have a list<string> which i want to assign to a expando(dynamic) object and create property as per the list<string>.
How do this?
List<string> propertyname=new List<string>(); propertyname.add("Name"); propertyname.add("Class"); Now i want to add this propertyname list to a object of expando so that it has property called Name and Class.