my %re = (
    boom => [ qw( abc ghi) ],
    doom => [ qw( mmm nnn) ],
    zapp => [ qw( xxx yyy) ],
);

foreach my $key (keys %hash) {
    $key =~ /$re{$_}->[0]_(.*)_$re{$_}->[1]/
        and $hash{$key} = $_.$1 for keys %re;
}