Net consideration from sale of any capital asset which is invested in construction or purchase of residential property is exempt from implication of capital gain to the extent of amount invested u/s 54F. In your case the amount of net gain received from sale of Land 1 will be exempted from capital gain tax if the same is invested in the construction of a residential property.
Gifting of a capital asset to brother doesn't attract capital gain implication. You can just execute a gift deed and get the relief.