use warnings;
use strict;

my %stops = map {$_=>1} qw/ I am the of and /;
my %terms = ( 'manager of sales' => 1 );
my $str = 'I am the senior manager of sales and of marketing';

my ($re_stops) = map {qr/\b(?:$_)\b/i} join '|', map {quotemeta}
	sort { length $b <=> length $a or $a cmp $b } keys %stops;
my ($re_terms) = map {qr/\b(?:$_)\b/i} join '|', map {quotemeta}
	sort { length $b <=> length $a or $a cmp $b } keys %terms;

my @s = split /($re_terms)/, $str;
for my $i (0..$#s) {
	if ($i%2) {
		print "*", $s[$i], "*\n";
	}
	else {
		$s[$i] =~ s/$re_stops//g;
		$s[$i] =~ s/^\s+|\s+$//g;
		print $s[$i], "\n";
	}
}

__END__

senior
*manager of sales*
marketing