How to steal a square on a distant continent to work the Great Barrier Reef?

Question

Came across the following situation:

Exploring the world by ship, I found the "Great Barrier Reef", 2 hexes off of a different continent. After some research, it appears the only way to work these tiles is with workers from a city.

Unfortunately, the "Reef" tiles are adjacent to two other civilizations and the "Cape Town" CS. One of the civs is attacking the CS. The Cape Town tiles seem to be the best location for a city, and Cape Town has asked for assistance against the attacking civ.

Are there any good options other than taking Cape Town?

Answer 1

Why is it so important for you to work the Reef? It will be hard for you to establish a city, then work on your culture in the city. The easiest way is to make a city nearby (if you don't wanna take Cape Town) and buy off the tiles you want.

Answer 2

Cities can't be built within 3 tiles of another city, and capitols and city states cannot be razed. So, if the spot is within 3 tiles of Cape Town, it is never going to be available for settling no matter what you do. You can't settle in claimed tiles, so if all the other available tiles are owned then you need to capture a nearby city. If it doesn't own the tile you want but its borders are within 2 tiles of it, you can use a Great General's Citadel ability to claim the tiles for yourself - it automatically expands the borders to all the tiles next to the citadel, and can be placed next to any of your borders (even inside enemy land).