My friend has 50% share in 2 person New York s-corp. I want to lend money to my friend with following conditions using some legal vehicle (promissory note/contract etc):

1. Collateral: His interest in s-corp.
2. Entitle to 30% of his annual profit share.
3. Entitle to 30% of his share if the business is sold.
4. There should not be any taxes on initial investment.
5. Be as tax efficient as possible for both of us. There should be no double taxation, I will pay taxes on the profit I receive but my friend should be able to deduct whatever he pays me on his taxes.

I cannot become part of s-corp or directly lend money to s-corp as other 50% partner in s-corp does not want to deal with it.