Using Insert with case

Hi

select
case when somevariable = 2
then (insert into pipe (line)
select bob.edge_data.edge_id
from bob.edge_data, bob.node, pipe
where st_intersects(st_startpoint(bob.edge_data.geom), bob.node.geom)
and bob.node.node_id = 415
and pipe.id = 1)

I am attempting to use the above. However, with or without the enclosing brackets I get a syntax error on the word into.

Help will be appreciated.

Bob