List group items may be buttons instead of list items (that also means a parent <div> instead of an <ul>). No need for individual parents around each element. Don't use the standard .btn classes here.

<div class="list-group">
  <button type="button" class="list-group-item">Cras justo odio</button>
  <button type="button" class="list-group-item">Dapibus ac facilisis in</button>
  <button type="button" class="list-group-item">Morbi leo risus</button>
  <button type="button" class="list-group-item">Porta ac consectetur ac</button>
  <button type="button" class="list-group-item">Vestibulum at eros</button>