If pirates are taken to be 6 5 4 3 2 1…with the number corresponding to the seniority-
Let’s then start with 2 pirates and go further as done in the 5 pirate puzzle problem,

2 pirates- 1 and 2. Obviously 2 will keep the coin.

3 pirates-   3 will give it to 1 and 1 knows he won’t get anything if he says no as when 3 pirate is killed, case 2 reduces to case 1.

4 pirates-   4 gives it to 2. who (since is intelligent) would say yes to.

5 pirates- 5 obviously won’t give it to 2. But even if he gives the coin to 4,3 or 1. All of rest three will say no to it. So, this condition can’t be stabilised .  So 5 would be killed no matter what and we’ll go back to case 3 with 4 pirates.

 6 pirates-    6 knows 5 would always want him to live or else if 6 dies, 5 eventually dies and we go back to case 3 where 2 gets the coin. So 6 wont give it to 2 as he would be rich one way or the other. Thus, he will give the coin to any of 4,3 or 1 . Any of them would say yes.
So 6,5 and (4/3/1) would poll yes and captain saves himself.