Diners Club as well. AS doesn’t do AMEX/Chase/Citi/Cap1/etc. They are BofA, and thus they don’t have a bank transfer partner.
Personally I would use a different program to get the AS flights, if that is what you need, or a different program for the AS partner you need rather than doing something dumb like a two way transfer that will waste HUGE value, like AMEX->Marriott/Hilton->Alaska, or Chase->IHG->Alaska.