The following solution is based on an example of split with capture I posted earlier...

use strict;
use warnings;
use Data::Dumper;

my $str = 'one "two three" four five "six seven eight" nine';

my @words = map { $_ || () } split /"(\\"|.*?)"|\s+/, $str;

print Dumper(\@words);
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And the output is -

$VAR1 = [
          'one',
          'two three',
          'four',
          'five',
          'six seven eight',
          'nine'
        ];
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