using System;

using AutoMapper;

public class Program

{

    public static void Main()

    {

        Mapper.CreateMap<string, Class>()

            .ConstructUsing(str => new Class { MyProp = str });

        Mapper.Map<Class>("FOOBAR").Dump();

    }

}

​

public class Class

{

    public string MyProp { get; set; }

}

​