The Use of Intermediates with Preformed Disulfide Bridge for the Synthesis of Oxytocin and Deamino-oxytocin

The disulfide-bridged hexapeptides 6a and 6b have been prepared from benzyl-protected intermediates. Coupling of 6a and 6b with prolyl-leucyl-glycine amide afforded deamino-oxytocin ( 7a ) and the protected oxytocin derivative 7b , respectively; the latter was converted to oxytocin ( 7c ) by removal of the Boc protecting group.