You can achieve this by checking where you are in the loop and outputting markup at the appropriate time. Within the object that holds the query results is a counter that keeps track of the current post, $wp_query->current_post. Note that it is zero-indexed, so first is 0, 2nd is 1, etc..

<?php
while( have_posts() ):
    the_post();

    if( $wp_query->current_post == 0 ):

        // this is the first post
        ?>
            <div class="one">
                <?php the_title(); ?>
            </div>
            <div class="two">
        <?php

    elseif( $wp_query->current_post > 0 && $wp_query->current_post < 4 ):

        // this is the second - fourth posts
        the_title();

    elseif( $wp_query->current_post == 3 ):

        // this is the fourth post
        ?>
            <!-- close div class=two -->
            </div>
        <?php

    endif;

endwhile;