using System;

using System.Reflection;

​

namespace Oooo

{

    class Base

    {

        public int Some { get; private set; }

​

        public Base()

        {

            Some = 12345;

        }

    }

​

    class Der : Base { }

​

    public class Program

    {

        public static void Main()

        {

            Der d = new Der();

            d.GetType()

                .GetProperty("Some")

                .DeclaringType

                .GetProperty("Some", BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance)

                .SetValue(d, 12, BindingFlags.NonPublic | BindingFlags.Instance, null, null, null);

            Console.WriteLine(d.Some);

        }

​

    }

}