^^^ exactly that. The rule is generally that your "principal purpose" can't be to avoid taxes (in this case). There is also the "economic substance doctrine" which actually codifies the above principle. Basically, you have to have a non-tax reason to do something -- even if the tax reasons are ridiculously great.

There are certain things where you are allowed to write into the IRS and get a Private Letter Ruling. "Business Purpose" is not one of them.