Substitute Regex with 'e'

[Ramprasad A Padmanabhan]

Hi 

   I want to so a substititue a string Say 
    
   my %hash = ( 1130, "a" , 2100, "b");

    $x = 'SOMEJUNK 1130';

    # I want $x to be    '1130a'
    
   # This regex does not work 
    $x=~s/^(.*?) (\d+)/ $2 . { defined $hash{$2} ?  $hash{$2} :
'NOTFOUND' } /e;

Can someone fix the regex for me

Thanks
Ram