using System;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        var json = @"{""struct"":""BLUB""}";

        var test = JsonConvert.DeserializeObject<Test>(json);

        Console.WriteLine(JsonConvert.SerializeObject(test));

    }

}

​

public class Test

{

    [JsonProperty(PropertyName = "struct")]

    public TestStruct Struct {get;set;} 

}

​

public struct TestStruct

{

    public string Foo {get;}

    public static implicit operator TestStruct(string val)

    {

        return new TestStruct(val);

    }

    public TestStruct(string val)

    {

        Foo = val;  

    }

}