NginX - Wordpress under subfolder

I'm having little problems with Nginx and Wordpress. We have not standard configuration where everything except defined folders and files will be sent to wordpress. And wordpress is in subdirectory /wordpress but it must behave like it's not. For now we managed to get this configuration working and here is part of it:

if ($request_uri ~ "^/(folder1|folder2|folder3|folder4)/") {
break;
}

if ($request_uri ~ "^/(file1\.ext1|file2\.ext2|file3\.ext3|file4\.ext4)") {
break;
}

if ($request_uri ~ "^/$") {
break;
}

if ($request_uri ~ "^/\?m\=[0-9]$") {
break;
}

rewrite ^/(.*)$ /wordpress/$1;

location ~ /wordpress {
location ~* /(?:uploads|files)/.*\.php$ {
deny all;
}

rewrite /wp-admin$ /wp-admin/ permanent;

location ~ ^/wordpress/wp-admin/ {
include /etc/nginx/settings/moderator-access.conf;
}

location ~* \.(js|css|png|jpg|jpeg|gif|ico)$ {
expires max;
}

rewrite ^/?(.*)$ /wordpress/index.php?$1;

try_files $uri $uri/ /index.php?$args;

# Handling PHP files
include settings/php-fpm.conf;
}

Problem with this config (except being complex :)) is that when someone goes to www.example.com/wp-admin/ it gives 404 blank page. But what's interesting if you type www.example.com/wp-admin/index.php everything works excellent. Doe's anyone have idea how to fix this?

P.S. We recently switched to Nginx and we are still struggling with it :) It's not easy after 7 years on Apache to switch :)