In Redshift, how do you combine CTAS with the "if not exists" clause?

I'm having some trouble getting this table creation query to work, and I'm wondering if I'm running in to a limitation in redshift.

Here's what I want to do: I have data that I need to move between schema, and I need to create the destination tables for the data on the fly, but only if they don't already exist.

Here are queries that I know work:

create table if not exists temp_table (id bigint);

This creates a table if it doesn't already exist, and it works just fine.

create table temp_2 as select * from temp_table where 1=2;

So that creates an empty table with the same structure as the previous one. That also works fine.

However, when I do this query:

create table if not exists temp_2 as select * from temp_table where 1=2;

Redshift chokes and says there is an error near as (for the record, I did try removing "as" and then it says there is an error near select)

I couldn't find anything in the redshift docs, and at this point I'm just guessing as to how to fix this. Is this something I just can't do in redshift?

I should mention that I absolutely can separate out the queries that selectively create the table and populate it with data, and I probably will end up doing that. I was mostly just curious if anyone could tell me what's wrong with that query.