Help with rewrite(loop error)

Hello my dear friends

I have some problem with rewrite.

I have example.com

I need 301 redirect:
example.com/index -> example.com
example.com/index.html -> example.com
example.com/about.hrml -> example.com/about
example.com/contacts.php -> example.com/contacts

Please help!

I try to do somthing like this:
rewrite ^/index.html$ $scheme://$host permanent;
rewrite ^(/.+)\.html$ $scheme://$host$1 permanent;

But i have redirection loop error