Visual Studio Replace to Change Delimiters

I have code open and want to change string delimiters from single quotes to square brackets using Visual Studio I want to search for the pattern (double quotes are NOT part of the string/pattern):
" AS 'something here'"

and replace it with: 

" AS [something here]"

So basically looking for a single space the word AS, another space, a single quote, a string, another single quote and want to replace the first quote with [ and the second with ]. I want to do this within the search/replace box (Ctrl-H) in VS with regualar expressions selected. I'm a LONG way from being a RegEx expert so looking for some help. Might mention, if not adding a lot of complication to the search string, the space surrounding the AS keyword could be more than one space or could be tab(s). Multiple spaces and/or tab characters can be replaced with just a single space.

TIA