Abstract: Disclosed are novel compounds which are used as linkers to bind peptides to solid support. The novel compounds can be used for the purification of synthesized peptides and are represented by the following structural formula:X--NH--(CH.sub.2).sub.n --SO.sub.2 --CH.sub.2 --CH.sub.2 --O--CO--Y;n is an integer from 1-4; X is a thiol functionalized with a protecting group that is cleavable under acidic conditions; and Y is a leaving group.

Abstract: Disclosed is a method of purifying a mature peptide with a free N-terminus group from a mixture of peptides comprising the mature peptide and immature end-capped peptides. The peptides are bound to a solid-phase support and are produced by solid phase synthesis. The mixture is contacted with a linker comprising a functional group at each terminus. The functional group at one terminus has the structure --SO.sub.2 --CH.sub.2 --CH.sub.2 --X, wherein X is an activated carbonate group which reacts selectively with N-terminus of the mature peptide to form a urethane linkage. The functional group at the other terminus is a thiol protected with an acid labile group. After cleaving the peptides from the solid support and thiol protecting group with acid, the mature peptide is separated from the mixture by forming a covalent bond between the liberated thiol and a solid support. Treatment with base cleaves the mature peptide from the linker to give a purified mature peptide.