أرسل هذا في رسالة قصيرة: A simple and efficient preparation of bis(indolyl)methanes catalyzed by HCl/silica gel under solvent-free conditions

   _____   _    _    _    _     ______   _    _   
  / ___// | || | || | |  | ||  /_   _// | || | || 
  \___ \\ | || | || | |/\| ||   -| ||-  | || | || 
  /    // | \\_/ || |  /\  ||   _| ||_  | \\_/ || 
 /____//   \____//  |_// \_||  /_____//  \____//  
`-----`     `---`   `-`   `-`  `-----`    `---`