Converting an object into JSON object by development shop

I've created a hierarchy of classes to store all my JSON data. Here's a snippet:

    public class Product
    {
        public string body_html { get; set; }
        public string created_at { get; set; }
        public string handle { get; set; }
        public int id { get; set; }
        public string product_type { get; set; }
        public string published_at { get; set; }
        public string published_scope { get; set; }
        public object template_suffix { get; set; }
        public string title { get; set; }
        public string updated_at { get; set; }
        public string vendor { get; set; }
        public string tags { get; set; }
        public List<Variant> variants { get; set; }
        public List<Option> options { get; set; }
        public List<Image> images { get; set; }
        public Image2 image { get; set; }
    }

    public class RootObject
    {
        public List<Product> products { get; set; }
    }

I then programmatically update all the data in the Products. My goal is to upload the new product info back into Shopify doing something like this:

object json = JsonConvert.SerializeObject(prod, Formatting.Indented);

                        dynamic createProductResponse = client.Put("/admin/products/123456.json", json);

This is giving me the error (422) Unprocessable Entity.

I've looked through documentations such as this one: http://james.newtonking.com/projects/json/help/index.html?topic=html/SerializingJSON.htm#

I did a test and was able to update my products by passing a single JObject that looked something like this:

                    JObject obj = new JObject
                    {
                    {"product", 
                        new JObject{
                            {"title", "Product Name"},
                            {"product_type", "Men"},
                            {"id", "150056881"},
                            {"published_at", new DateTime(DateTime.UtcNow.Ticks, DateTimeKind.Utc)},
                            {"vendor", "Vendor Name"},
                            {"variants", new JArray{
                                new JObject
                                {
                                    {"barcode", null},
                                    {"compare_at_price", "100.00"},
                                    { "created_at", "2013-08-04T10:43:20-07:00"},
                                    { "fulfillment_service", "manual"},
                                    { "grams", "100"},
                                    { "id", "343061321"},
                                    { "inventory_management", "shopify"},
                                    { "inventory_policy", "deny"},
                                    { "option1", "DARK BROWN"},
                                    { "option2", "7"},
                                    { "option3", null},
                                    { "position", 1},
                                    { "price", "75.00"},
                                    { "product_id", "150056881"},
                                    { "requires_shipping", true},
                                    {"title", "DARK BROWN / 7"},
                                    {"sku", "SKU12345"},
                                    {"taxable", true},
                                    { "updated_at", "2013-08-04T10:43:20-07:00"},
                                    { "inventory_quantity", 123}
                                }
                            }}
                        }
                    }
                 };

Thanks for any help you can offer!