Json deserializing object as Dictionary

I'm serializing object let's call it X to Json, one of fields in X is type of object (here i assign different classes instances).

public object value { get; set; } 

So after deserialization I get value as Dictionary<propertyName, value>

["x", "valX"] ["y", "valY"] 

I understand why this works that way, so my question is what is the best way to create propper class instance according to this value I can create new instane and assign propertieces:

new A() { x = value["x"], y = value["y"], . . . } 

But is there any beter way to achieve that?