Solid phase synthesis of gastrin I

A successful synthesis of human gastrin I in 60% overall yield based on the first residue attached to a benzhydrylamine-resin was achieved by the stepwise solid-phase method. The synthesis was carried out on a 1% crosslinked polystyrene support, using conventional benzyl-based side chain protecting groups and final deprotection with different acidic protocols. Several improvements in this general approach were applied, including new scavengers, new resin attachment and especially a new technique that allows the strong acid reactions to occur by an S_N2 mechanism.