Syncronous and Asyncromous are layer 1 properties. The WAN technologies you mention are layer 2 technologies. ISDN can run Sync and Async data on it. PPP is the same. Frame Relay can also run on an Async or Sync line. ATM is Async.
The Difference between the Sync and Async is that Sync clocks off the line. The clock is part of the data. Async the clocking is not on the line. The end equipment uses their internal clocking to receive and transmit data.
