Hycram resin

Peptide cleavage from the allyl-linker resin is achieved with morpholine in large excess in the presence of tetrakis(triphenylphosphine)palladium (10mol% based on the allylic substitution of the resin). (3-HYCRAM resin is a modification of HYCRAM containing a P-alanine residue as a spacer between the crotonoyl unit and the resin. It has been used for the solid-phase synthesis of glycopeptides by the Boc and Fmoc strategies.b 1 Difficulties may be... 

W Kosch, J Maerz, KVD Bruch, H Kunz. Solid phase synthesis of glyco-peptide antigens on HYCRAM resin utilizing the allylic anchor principle. Proceedings of Innovation and Perspectives in Solid Phase Synthesis. Third International Symposium, Oxford, 1993, pp 267-272. 

Hycram resin, hydroxycrotonoylamidomethyl resin, an allyl-based handle resin connection for SPPS of peptides and, especially, for glycopeptides, which is stable to base and mild acid. The cleavage of the final product from the resin occurs under neutral conditions by treatment with (Ph3P)4Pd/THF/morpholine, and does not affect Boc, Fmoc, or glycosidic bonds [H. Kunz, B. Dombo, Angew. Chem. Int. Ed. 1988, 27, 711]. 

The allylic HYCRAM derivative was subsequently modified by insertion of a standard amino acid between the aminomethyl resin and the hydroxy butenoic acid moiety. Using this allylic anchor, the resin-linked, glycosylated HIV peptide T-derivative 164 was synthesized by application of Fmoc amino protection and sidechain protection with lert-butyl groups. The lac-tosamine peptide T (165) could be released from the resin by application of the palladium(0)-catalyzed allyl-transfer reaction to V-methyl aniline as the allyl acceptor. 

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