Synonyms for As to:

adj.

compared (adjective)
related.
concerning (adjective)
regarding.
regarding (adjective)
in relation to, in regard to.

n.

as to (noun)
in regard to, regarding, vis-a-vis, concerning, with regard to, with reference to, related, with respect to, related to, in relation to.

prep.

apropos (preposition)
regarding, with respect to, with reference to, concerning.
toward/towards (preposition)
with regard to.

Other synonyms:

regarding
regarding.