For the CTR, there is only one transaction -- the deposit of cash. The purchase of the cashier's check does not involve cash.
Note: If the cashier's check purchase had been for an amount between $3,000 and $10,000, inclusive, you'd have to treat it as a cash purchase of a monetary instrument for record keeping purposes even though the cash was actually deposited to the account.
John S. Burnett
Fighting for Compliance since 1976
Bankers' Threads User #8