Module in subfolder

Is it possible to have a module in a subfolder? For example put all modules in folders like ‘frontend’ and ‘backend’?

I tried to do this:


'modules'=>array(

     'frontend.site'

)

and:


'modules'=>array(

     'frontend'=>array('site')

)

But that didn’t work.

I know about sub-modules, but I don’t like to create empty parent modules.