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 SN2 mechanism.