Rink resin is originally developed for SPS of peptide amides. Now the scope of its application is extended from carboxylic amides to the immobilization of amines, substituted amides. Libaries of primary amines have been synthesized by the treatment of Rink amine resin with aldehyde to form aldimines, which are subsequently reacted with Grignard reagents or lithium reagents to yield amines that are not commercially available [1]. These amines are released from resin by treatmnet with TFA-water-DCM (5:5:90) for 5 h at room temperature. N-Substituted amides are obtained by reducing the above-mentioned aldimines with Na(CN)BH₃ to the corresponding amines, followed by acylation with acid chlorides or symmetrical anhydrides. The produts are cleaved with TFA-water-DCM (5:1:94) for 20 min at room temperature. Direct functionalization of Rink amide resin with nucleophiles has also been reported [3]. The Fmoc protecting group can be readly removed with 20% piperidine in DMF prior to the above manipulation.

[1] A. R. Katritzky, et al. Tetrahedron Lett., 1997, 38, 7011.

[2] E. G. Brown, et al. Tetrahedron Lett., 1997, 38, 8457.

[3] R. A. Tommasi, Tetrahedron Lett., 1998, 39, 5477.