using System;

using AutoMapper;       

​

public class Program

{

    public static void Main()

    {

        Mapper.CreateMap<Source, Dest>()

            .ForMember(dest => dest.Property, opt => opt.MapFrom(src => src.Parent.Child.Child.Property));

        var source = new Source();

        var result = Mapper.Map<Dest>(source);

        result.Dump();

    }

}

​

public class Dest

{

    public string Property { get; set; }

}

​

public class Source

{

    public Class1 Parent { get; set; }

}

​

public class Class1

{

    public string Property { get; set; }

    public Class1 Child { get; set; }

}