If loop with two conditions

I want to delete all pdf files in a directory, except for two with file names defined as the variables exception1 and exception2.

chcp 65001
setlocal ENABLEDELAYEDEXPANSION
set pathname=%~p1
set letter=%~d1
pushd %letter%%pathname%
chcp
set exception1="218-0553.2.pdf"
set exception2="218-0553.2 test.pdf"
pause

dir *.pdf
for %%f in (*.pdf) do (
    if /i not "%%~nxf"=="%exception1%" (
        if /i not "%%~nxf"=="%exception2%" (
            echo Deleting "%%f"
            del "%%f"
        ) else (
            echo Keeping "%%f"
        )
    ) else (
        echo Keeping "%%f"
    )
)
popd
endlocal

This generates an error message:

else was unexpected at this time

I've also tried this, which doesn't work either:

if /i not "%%~nxf"=="%exception1%" and not "%%~nxf"=="%exception2%"

Is there something Im missing?

You are double quoting the exception filenames.

First you have this:

set exception1="218-0553.2.pdf"
set exception2="218-0553.2 test.pdf"

and later

if /i not "%%~nxf"=="%exception1%" (

which will evaluate to

if /i not "%%~nxf"==""218-0553.2.pdf"" (

So changing the exception values to

set exception1=218-0553.2.pdf
set exception2=218-0553.2 test.pdf

will fix it.