For a start there is a syntax error in the pattern you have shown: '[^\]' the "\" escape character is making the "]" into a literal closing square parenthesis which means the character set definition is not terminated.
Secondly, I realise that it is in a different forum on this site, but there is a "Posting Guidelines" sticky note in the "Construction" forum that tells you how to ask this type of question. You have provided much of the information we require but I suggest that you read the guidelines to make sure.
Also, can you provide us with some sample input text to try any suggested patterns we may come up with; also the output that you expect from the process.
Finally, looking at your pattern, I can't really see how it is intended to work. Also, can Java literals contain literal double-quote characters if they are escaped in some way? If so how?
Assuming that literal double-quote characters are represented as 2 consecutive double-quote characters (e.g. "She said ""Hello"" and smiled"), I would probably try something like (untested)
(Note: this is a raw regex pattern - you may well have to add to it to represent it as a string in your programming language or test platform).
This assumes that the "singleline" option is set and that all literals are have the correct syntax (i.e. have balanced double-quotes etc), and works by locating the opening double-quote, and then repeatedly looks for either a "literal double-quote or any character that is NOT a double-quote, and finally the closing double-quote. I think the first part of your pattern is supposed to handle a blank string; my suggestion will do that without making it a special case.