Try to strigify the products and deserialize on server.

data.append('Products', JSON.stringify(products));

on Server (Assume product class with id, value) using JavaScriptSerializer

var productsStr = data["products"].ToString()
var deserializedProducts = serializer.Deserialize<List<Product>>(productsStr);

Try to strigify the products and deserialize on server.

data.append('Products', JSON.stringify(products));

on Server (Assume product class with id, value) using JavaScriptSerializer

var serializer = new JavaScriptSerializer();
var productsStr = data["products"].ToString()
var deserializedProducts = serializer.Deserialize<List<Product>>(productsStr);