I have a table called "gebaeude" with all types of buildings in the city. 
In the following I want to use a Buffer around the central train station that has the id="2" and a radius of 1000m. Then I want to select the building types "kinergarten" and "school" that are within this radius by intersecting them with the buffer. What I did looks like this:

    WITH center AS (
         SELECT ST_Buffer(geom, 1000) FROM gebaeude 
         WHERE id='2')
    SELECT gebaeude.name AS "Name",
            ST_Distance(center.geom, gebaeude) AS Distanz
    FROM gebaeude, center
    WHERE (gebaeude='school' OR gebaeude.type='kindergarten')
    AND ST_Intersects(gebaeude.geom,center.geom);

I get the following error: 

> ERROR:  column center.geom does not exist
LINE 5: ST_Distance(center.geom, gebaeude) AS Distanz
                    ^

What am I doing wrong?