<div class="btn-group-vertical">
    <button type="button" class="btn btn-default">Button</button>
    <button type="button" class="btn btn-default">Button</button>
    <div class="btn-group">
        <button id="btnGroupVerticalDrop1" type="button" class="btn btn-default dropdown-toggle"
                data-toggle="dropdown">Dropdown
        </button>
        <ul class="dropdown-menu" role="menu" aria-labelledby="btnGroupVerticalDrop1">
            <li><a href="#">Dropdown link</a></li>
            <li><a href="#">Dropdown link</a></li>
        </ul>
    </div>
    <button type="button" class="btn btn-default">Button</button>
</div>