I have the same problem with here http://wordpress.org/support/topic/help-pointing-to-wordpressindexhtml-does-not-work, but this is not resolve and closed topic.
The site has a static html live site and transferred in wordpress CMS, so in SEO matter the index.html is needed to be redirect in wp homepage http://mysite.com/dev/, but when I redirect it using redirect 301 the browser flash an error (The page isn't redirecting properly). And please note: I am using custom permalink plugin to include .html extension in inerpages.
I know that many people here have a sufficient experience, please help
Remove all manual .htaccess modifications and install redirection plugin: http://wordpress.org/extend/plugins/redirection/.
Go to Tools>Redirection and enter a new reidrection
Source URL: /myblog/index.html
Target URL: /myblog/