Lexing perl - regular expressions and /e

my $foo = 'foo';

# OK
$foo =~ s{o}{{ 1 }}e;
$foo =~ s{1}{{
    2
    # aaa bbb
}}e;

# Failure
$foo =~ s{o}{{ "}" }}e;
$foo =~ s{o}{{ 1 # aaa bbb }}e;
$foo =~ s{o}{{
    1
    # aaa } bbb
}}e;
$foo =~ s{o}{{
    1
    # aaa { bbb
}}e;