Well, unless you are an off-season bodybuilder getting ready to start a cocktail of fancy expensive drugs ... nope.
Like Slap pointed out, to safely drop the weight, you need to take your time.
Assuming you don't have a ton of training experience, and aren't super tall, you probably won't see a full six pack before the 160s; less if you're short, higher if you're taller. That even might be generous.
So you likely have about 150lbs to drop to hit your goal. If you are super, mega dedicated, have professional medical, nutritional and physiological supervision I'd say you might manage a year and a half. To be realistic though? Probably about 3 years.
That is not to say you can't achieve some amazing results in six months. You could definitely drop 50+ pounds in those first few months, as when you first start dieting and exercising you are going to get the most extreme results.
So best of luck, and if you really want to see a difference, find some professional help to guide you.