You can make much more easier, if you can wrap the target div's in another container like
<div class="btnsContainer">
<div class="btn-group" data-toggle="buttons">
<label class="btn btn1"><input type="checkbox" class="theBtn1"/>btn1</label>
<label class="btn btn2"><input type="checkbox" class="theBtn2"/>btn2</label>
<label class="btn btn3"><input type="checkbox" class="theBtn3"/>btn3</label>
</div>
</div>
<div>
<div class="Div1" style="display:none;">div1</div>
<div class="Div2" style="display:none;">div2</div>
<div class="Div3" style="display:none;">div3</div>
</div>
then
$(document).on("change", ".theBtn1", function () {
var $nxt = $(this).closest('.btnsContainer').next();
$nxt.children().not('.Div1').stop().slideUp().removeClass("active");;
$nxt.children('.Div1').stop().slideToggle().toggleClass("active");;
});