Simply place normal button indide Ajax.BeginForm and on click find parent form and normal submit. Ajax form in Razor:
@using (Ajax.BeginForm("AjaxPost", "Home", ajaxOptions))
{
<div class="form-group">
<div class="col-md-12">
<button class="btn btn-primary" role="button" type="button" onclick="submitParentForm($(this))">Submit parent from Jquery</button>
</div>
</div>
}
and Javascript:
function submitParentForm(sender) {
var $formToSubmit = $(sender).closest('form');
$formToSubmit.submit();
}