Google not indexing after removing date from permalink

I recently changed my Permalink Settings to http://www.xxx.com/blog/sample post/ from
http://www.xxx.com/blog/2015/04/sample-post/.

When I do a Google search my old Permalink title comes up. Upon hitting the search result I then get a page error as the old Permalink title is no longer valid.

I have had Google crawl the site since making this change with no difference in the results.

I realize that I can go back and change the Permalink title to include the Month and year but I would prefer to get this to work.

Any clues??