The functionalization of polymeric organolithiums (PLi) with 3,4-epoxy-1-butene (EPB) in a hydrocarbon solution yielded the corresponding hydroxybutene-functionalized polymers in high yields (>95%). Three modes of addition of]PLi to EPB were observed (1,4, 3,4, and 4,3). The products and chain-end structures were characterized by H-1 NMR, C-13 NMR, attached-proton-test C-13 NMR, calculated C-13 NMR chemical shifts, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The regioselectivity of the addition depended on the PLi chain-end structure, the reaction conditions, and the addition of lithium salts or Lewis bases. In the absence of additives, the functionalization of poly(styryl)lithium (PSli) produced equal amounts of 1,4-, 3,4-, and 4,3-addition, as determined by quantitative C-13 NMR analysis. The use of a low temperature (6 degreesC), inverse addition, the addition of triethylamine (TEA; [TEA]/[PSLil = 20) as a Lewis base, or dienyllithium chain ends produced polymers with only the 1,4-addition product. Mild dehydration of the hydroxybutene-functionalized polymer with p-toluenesulfonic acid produced the corresponding diene-functionalized macromonomer, as shown by MALDI-TOF MS. (C) 2003 Wiley Periodicals, Inc.