Stereochemistry of β-carboxy- and β-hydroxymethyl-muconic derivatives

Abstract

N.m.r. spectroscopy has been used to determine the stereochemistry of various β-carboxy- and β-hydroxymethylmuconic derivatives. Long-range spin coupling between the olefinic protons is discussed. Isomerisation of the αβ- and γδ-double bonds has been shown to involve participation of the δ- and α-carboxy-groups, respectively. Treatment of both β-carboxy-cis-cis- and cis-trans-muconic acid with hot aqueous alkali gave, in contrast with an earlier report, trans-glutaconic acid rather than β-carboxy-trans-trans-muconic acid. A convenient preparation of δ-deuteriated β-carboxymuconic derivatives is described.