Hi
I would have to agree with Dana - and again if I have read your question correctly.
Your current site has been penalised and basically you want to move to a new url to rank highly but not lose brand awareness or direct visitors to your site. If this is what your asking then its not possible, Google will simple pass the penalty to the new url.
Here is the solution, but it requires hard work and will take time.
Resolve the penalty and boost your rankings, I am only guessing that you have been hit by Penguin as its just rolled, but if you have. Do a full link audit, work out which links are toxic and are causing you to drop rankings. After you have complied this list you have two options and it depends if you have a manual penalty or just been hit by Penguin.
Manual Penalty: you will need to contact all these web masters and try and get as many as the links removed as possible. Keep evidence that you have contacted these web masters, emails etc. Then the ones you haven't been able to get removed add to a disavow file and upload in WMT. Then go through the reconsideration request - at this stage you will need to show all the emails you have sent and a list of all the links you have got removed.
Been hit by Penguin: A lot easier (but will take longer to recover), once you have got you list of bad links, simply add them as a disavow file. Keep this disavow file as any future disavow files you do, you need to add to this original list. Now you just have to sit back and wait for Penguin to roll again and unfortunately we haven't been told yet when this will roll again and how frequently it will roll.
If it is the case you have been hit by Penguin, you need to do some white hat techniques of building links. If the bad links were done by you, then you might want to read this article: http://moz.com/beginners-guide-to-seo/growing-popularity-and-links. If the links we're built by a previous SEO company / employee - make sure that the old tatics aren't used again. Sit down with the SEO agency and explain what you want. If its done by your current SEO agency, I would personally fire them, no agency in my opinion should be building bad links. Penguin has been out long enough for SEO agencies to have changed tactics of link building, but if you do want to stay with them, explain you want a different strategy to link building.
Basically 301 won't work in the long term, you will lose your direct customers and get the penalty passed anyway.