ArcMap 'in_memory' trouble?

Being new to ArcMap, and ArcPy I have a problem with a script including several geoprocessing functions.
The number of functions inspired a search for a means to save outputs (subsequent inputs) to memory, leading to the ‘in_memory’ assist provided by ArcMap.

However the following script errors out at the RasterToPolygon_Conversion() and I am unsure why…

import arcpy

arcpy.CheckOutExtension("spatial")
arcpy.env.overwriteOutput = True
arcpy.env.workspace = "C:\Users\Important\testMap.mxd"

DEM_raster_layer = "C:\canyon.tif"
Camera_point_layer = "C:\birdsEye.shp"

# Process: Visibility analysis
arcpy.gp.Visibility_sa(DEM_raster_layer, Camera_point_layer, "in_memory", "",
                      "FREQUENCY", "NODATA", "0.00001201","FLAT_EARTH", "0.13", "", "",
                      "OFFSETA", "", "", "AZIMUTH1", "AZIMUTH2", "VERT1", "VERT2")

# Process: Visibilty boundries cleanup
arcpy.gp.BoundaryClean_sa("in_memory", "in_memory\1", "ASCEND", "TWO_WAY")
arcpy.Delete_management("in_memory")

# Process: Visibility raster to polygon(s)
arcpy.RasterToPolygon_conversion("in_memory\1", "in_memory\2", "NO_SIMPLIFY", "")
arcpy.Delete_management("in_memory\1")

Here is the following error return:

Runtime error Traceback (most recent call last): File “”, line 32, in File “c:arcgisdesktop10.2arcpyarcpyconversion.py”, line 244, in RasterToPolygon raise e ExecuteError: ERROR 000582: Error occurred during execution.

Im guessing there is some syntax or logic mistake in this method?