Sync on premise Document Library with Cloud hosted SharePoint Server site in SharePoint 2013

Question

As per my requirement I need to Sync Document Library of on premise hosted SharePoint site with cloud hosted SharePoint Document Library. For that I had wrote EventReceiver on ItemAdded of on premise SharePoint site. Users of on premise SharePoint site and cloud hosted SharePoint site are different.

For implementing above functionality, I wrote custom code in which I send new HttpRequest to the cloud hosted SharePoint site from my code using the cloud hosted SharePoint site URL. But it will throw exception that File not Found.

So, When I debug the code I realize at time of defining the object of cloud based SharePoint site there are one property i.e. "ServerVersion" which is read only has not able to get value so that it will throw exception.

Can any one help me to complete this functionality...??

Is there any other code snippet that will help me to implement this functionality..??