Derive Initial investment based on Compounded returns

By "target corpus" I assume you mean target value. The formula for future value given a compounding rate of return r and a time period t is:

FV = PV * (1+r)^t

So to solve for PV just divide by the compounding effect:

PV = FV / ((1+r)^t)

But note that with most investments there exists risk, meaning some level of probability that the actual returns fluctuate from the target returns. So to say that the initial amount is "required" to get the target may not be completely accurate. You may end up with more or less from the target, but with that inital investment, the specified target should be expected (what you'll get on average, with some risk).