using System;

using System.Linq;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        string json = "{\"data\": { \"1\": { \"test\": { \"col1\": \"123\", \"col2\": \"name\" } }, \"2\": { \"test\": { \"col1\": \"345\", \"col2\": \"name2\" } }, \"3\": { \"test\": { \"col1\": \"456\", \"col2\": \"name3\" } }}}";

        var settings = new JsonSerializerSettings

        {

            Converters = new JsonConverter[] { new ObjectAsArrayConverter() }

        };

        JsonConvert.DeserializeObject<Root>(json, settings).Dump();

    }

    public class ObjectAsArrayConverter : JsonConverter 

    {

        public override bool CanConvert(Type type)

        {           

            return

                type.IsGenericType &&

                typeof(List<>) == type.GetGenericTypeDefinition() &&

                typeof(Data) == type.GetGenericArguments()[0];

        }

        public override object ReadJson(

            JsonReader reader,

            Type objectType,

            object existingValue,

            JsonSerializer serializer)

        {

            JObject obj = JObject.ReadFrom(reader).ToObject<JObject>();

            return obj.Properties()

                .Select(p => new { Index = int.Parse(p.Name), Value = obj[p.Name].ToObject<Data>() })

                .OrderBy(p => p.Index)

                .Select(p => p.Value)

                .ToList();

        }

        public override void WriteJson(

            JsonWriter writer,

            object value,

            JsonSerializer serializer)

        {

            throw new NotImplementedException();

        }

    }

    class Root 

    { 

        public List<Data> Data {get; set;}

    }

    class Data

    {

        public Test Test { get; set; }

    }

​

    class Test

    { 

        public string Col1{get; set;} 

        public string Col2{get; set;}

    }

}