1984 Volume 32 Issue 4 Pages 1326-1332
Methyl, ethyl, and isopropyl esters of six alkanesulfonic acids and five p-substituted benzenesulfonic acids were synthesized and their alkylating abilities were evaluated in terms of the chemoselectivity toward 4-(p-nitrobenzyl) pyridine (NBP) in phosphate buffer (pH 6.0) containing 60% acetone. The chemoselectivity constant toward NBP, SNBP, was defined as the logarithm of the ratio of the molar fraction of an alkylating sulfonate which is consumed for alkylation of NBP versus the molar fraction of the residual alkylating agent which is hydrolyzed in the buffer medium. It was found that SNBP was not only markedly dependent on the structure of the alkyl moiety of the molecule, but also appreciably dependent on the electronic nature of the leaving sulfonic acid moiety. The structure-chemoselectivity relationship is discussed.
