TypeAs

You can build an expression tree which contains an explicit reference or boxing conversion using Expression.TypeAs method. For example, you have the following code.

Employee e = new Employee();
object objEmp = e as object;

Here is the code that is required to build the same functionality using expression tree.

UnaryExpression typeAsExpression =
    Expression.TypeAs(
        Expression.Constant(e, typeof(Employee)),typeof(object));

Console.WriteLine(typeAsExpression.ToString());

Try it online