Dynamic SQL UNPIVOT and Select INTO temporary table

I know that there are a few questions out there on Dynamic SQL and Insert into temporary tables, but I cannot find an exact match for my particular problem.

I have data in 52 columns in ##tmp and I need to total these and store in ##tmp2.

Note: The syntax works fine if I remove the first line

 select * into ##tmp2 from

It's the "Select Into" that I have a problem with! My current Dynamic query provides the following syntax, but I cannot get this to work. Currently the open bracket after the initial "from" has no matching closing bracket.

I've tried various positions for the final ")" but get a mixture of

Incorrect syntax near ')' -- if placed at the end of the statement
Invalid column name 'wk' -- if added as  "from ##tmp) onto the second from"
Incorrect syntax near the keyword 'group'. -- if added after ")) as U"

Here's the current syntax

select * into ##tmp2 from(
select x,y,sum(wk) as mysum  from ##tmp
  unpivot (wk for nwk in ([1],[2],[3],[4],[7],[8],[9],[10],[11],[12],[13],   [14],[15],[16],
[17],[18],[19],[20],[21],[22],[23],[24],[25],[26],[27],[28],[29],[30],[31],[32],[33],[34],
[35],[36],[37],[38],[39],[40],[41],[42],[43],[44],[45],[46],[47],[48],[49],[50],[51],[52]))
 as u  group by x,y

Any ideas?