Assuming you mean you've got an array like @asdf = ('A', 'B', 'C', 'D', 'E', 'F'), you can create the hash like this:

use Data::Dumper;
my @asdf = (qw/A B C D E F/);
my %hash;
my $hr = \%hash;
for(@asdf) { 
    $hr->{$_} = { };
    $hr = $hr->{$_};
}

print Dumper \%hash;
[download]

That prints:

$VAR1 = {
          'A' => {
                   'B' => {
                            'C' => {
                                     'D' => {
                                              'E' => {
                                                       'F' => {}
                                                     }
                                            }
                                   }
                          }
                 }
        };
[download]