try this:

set quoted_identifier off

declare @statement nvarchar(255)

select @statement = 'BACKUP database [dbname] to disk = '+"'" +

'\\servername\E$\fullpath\dbname_db_' +

CONVERT(varchar(4), datepart(yy, getdate()))+

right('0' + CONVERT(varchar(2), datepart(mm, getdate())),2)+

right('0' + CONVERT(varchar(2), datepart(dd, getdate())),2)+

right('0' + CONVERT(varchar(2), datepart(hour, getdate())),2)+

right('0' + CONVERT(varchar(2), datepart(minute, getdate())),2)+

'.bak'+"'"

exec sp_executesql @statement

replacing with your desired server and pathname