# @a holds a list of string
my @a = ("a", "b", "c", "/", "\[", "\"");

#create a regex that matches every element in the array
my $re = do { qr/(@{[join ("|", map { quotemeta } @a)]})/ };
die "not a regex!" unless ref($re) eq "Regexp";

##</code><code>##

#you don't need to escape ;
... $chosen_C !=~ /^\*.{36};$re;/ ...

##</code><code>##

my $re = do { qr/^\*.{36};(@{[join ("|", map { quotemeta } @a)]});/ };
die "not a regex!" unless ref($re) eq "Regexp";

... $chosen_C !=~ $re ...