Iterate over .each() of a type, clone (this) then append() to another iterated set
HTML
<div class="thumbnails">
<li><a></a></li>
<li><a></a></li>
<li><a></a></li>
<li><a></a></li>
<li><a></a></li>
</div>
... more HTML code
<div class="article">
<li class="headline" ><a>1 headline</a></li>
</div>
<div class="article">
<li class="headline"><a>2 headline</a></li>
</div>
<div class="article">
<li class="headline"><a>3 headline</a></li>
</div>
<div class="article">
<li class="headline"><a>4 headline</a></li>
</div>
<div class="article">
<li class="headline"><a>5 headline</a></li>
</div>
JavaScript
$('.article .headline a').each(function(i) {
$(this).clone().appendTo($('.thumbnails li').eq(i));
});