Abstract Derivatives of psilocin with ω-functionalized alkyl spacers in position 1 of the indole ring were synthesized as haptens for use in a radioimmunoassay. Whereas the psilocin analogues with a 3-aminopropyl and a 4-aminobutyl moiety at the indole nitrogen decomposed during synthesis, the analogous 3-carboxypropyl psilocin derivative proved to be stable. This compound was coupled to bovine...