Create a DWG file from Sketch-upo
with SketchUp Pro:
• “File > Export > 3D Model”
• “File > Export > 2D Graphic”
the first can be used for 2D data too especially if exporting ‘true’ circles/arcs (instead of polylines) is desired.
for configuring the export options (DXF/DWG version) check the “Options…” dialog (for being most compatible use the ACAD version 2000).
for checking the exported DXF/DWG you may want use a viewer as e.g. the free Teigha Viewer f. Windows & Mac OS.