PREFIX n: <https://nap.nprod.net/>
SELECT ?name
WHERE {
    <https://nap.nprod.net/compoundcode/21> n:name ?name.
}
                

                  PREFIX n: <https://nap.nprod.net/>
SELECT DISTINCT ?compound ?compoundName ?synonym ?synonymName
WHERE {
    ?compound n:has_compoundcode <https://nap.nprod.net/compoundcode/21>.
    ?compound a n:compound.
    ?compound n:name ?compoundName.
    OPTIONAL {
        ?compound n:has_synonym ?synonym.
        ?synonym n:name ?synonymName.
    }
}
ORDER BY ?compoundName