可以使用ASP.NET Core的HttpClient和System.Threading.Tasks中的Task.Wait方法来同步等待HTTP请求的响应。例如，下面的代码将从指定的URL中获取JSON数据，并等待响应的结果：

using System;
using System.Net.Http;

public class MyClass
{
    public string GetDataSynchronously(string url)
    {
        using (var client = new HttpClient())
        {
            var response = client.GetAsync(url).Result;
            if (response.IsSuccessStatusCode)
            {
                var result = response.Content.ReadAsStringAsync().Result;
                return result;
            }
            else
            {
                throw new Exception($"Failed to get data from {url}. Error code: {response.StatusCode}");
            }
        }
    }
}