my %newhash;
foreach my $key1 (keys %oldhash) {
    foreach my $key2 (keys %{$oldhash{$key1}}) {
        foreach my $key3 (keys %{$oldhash{$key1}{$key2}}) {
            $newhash{$key1}{$key3} = $oldhash{$key1}{$key2}{$key3}{content}
        }
    }
}