A synthesis of the tetrapeptide sequence As-Ag of glucagon is described that employs various blocking groups, coupling procedures, and routes. The threonyl-phenylalanyl-threonyl-seryl sequence A5-A8 in the hyperglycemic hormone, glucagon (Foa and Galansino, 1962), has been prepared by three different groups within the past four years (Beyerman and Bontekoe, 1964; Schroder and Gibian, 1962; Wuns...
