Alcohols and phenols can be protected as levulinate (Lev) esters. Ester formation has been brought about, e.g. by reaction with an alcohol in the presence of DCC and DMAP: Tetrahedron Lett., 4875 (1976); 23, 2615 (1982). The same references describe facile, selective cleavage by the use of hydrazine hydrate in pyridine/acetic acid. For use of 2-Chloro-1-methyl-pyridinium iodide, in the formation of Lev esters, see: Tetrahedron Lett., 21, 381 (1980). Alternative cleavage methods include: borohydride in water: J. Am. Chem. Soc., 97, 1614 (1975); MeMgI: benzoate esters unaffected: J. Chem. Soc., Chem. Commun., 681 (1992); sodium sulfite/ bisulfite under neutral conditions, effective for Lev esters of nucleosides, carbohydrates and steroids: Chem. Lett., 585 (1988). Lev esters have also been prepared using 2-Ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline: Tetrahedon Lett., 23, 2615 (1982).
