c:\@Work\Perl\monks>perl -wMstrict -le
"use 5.010;
 ;;
 my $x = q{((A & B)' | (A & C & (A & B & D | (A & (B' & D)')'))};
 print qq{:$x:};
 ;;
 my $parenthetic = qr{ ( [(] (?: [^()]*+ | (?R))* [)] ) }xms;
 my $term        = qr{ ( [[:alpha:]] \w* ) }xms;
 ;;
 1 while $x =~ s{ (?: $parenthetic | $term) \x27 }{ '!' . ($1 // $2) }xmsge;
 print qq{:$x:};
"
:((A & B)' | (A & C & (A & B & D | (A & (B' & D)')')):
:(!(A & B) | (A & C & (A & B & D | !(A & !(!B & D)))):