• Reagent for protection of the 5'-phosphate of nucleotides as 2-pyridylethyl (Pet) esters. The group can be introduced by DCC-coupling, is stable to mild base, but can be cleaved by methoxide in pyridine-methanol: Chem. Ber., 103, 1032 (1970).
• Has also been used for carboxyl protection of amino acids. Pet esters are stable to both mildly acidic and basic conditions used to cleave such groups as Boc and Fmoc, and also to hydrogenolysis. Cleavage is by quaternization with methyl iodide in the presence of mild base: Tetrahedron Lett., 25, 3971 (1984); Angew. Chem. Int. Ed., 23, 716 (1984). See Appendix 6.