$string =~ /
		(									
			HIT								
			(?=								
				[^<]*						
				(?!							
					<a[^>]*>				
				)				
				.*?<\/a>					
			)								
			.*?<\/a>						
		)
	/x;

##</code><code>##

'<a href="#1">--HIT<a name="MUST NOT MATCH">--</a> <a href="#2">2</a>'

##</code><code>##

'<a href="#1">--HIT-<a name="MUST NOT MATCH">--</a> <a href="#2">2</a>'