A. cis,cis-Monomethyl muconate. A 1000-mL, three-necked, round-bottomed flask is equipped with a mechanical stirrer and an addition funnel ((Note 1), Fig. 1). The flask is charged with 400 mL of pyridine, 5 mL (0.12 mol) of methanol and 9.9 g (0.10 mol) of cuprous chloride under an atmosphere of nitrogen (Note 2). The resultant yellow solution is stirred vigorously at room temperature until the cuprous chloride dissolves (Note 3). The nitrogen is removed and oxygen is bubbled into the flask below the surface of the liquid for approximately 30 min (Note 4). A solution, composed of 1000 mL of pyridine, 5.5 g (0.05 mol) of 1,2-dihydroxybenzene (catechol), and 5 mL (0.12 mol) of methanol, is degassed and slowly added to the flask over a 2-hr period with efficient stirring (Note 5). The reaction mixture is stirred for an additional 30 min before the pyridine is removed at reduced pressure. The dark green residue is dissolved in 300 mL of ethyl ether (Note 6) and 300 mL of 6 N hydrochloric acid; this solution is stirred for 10 min and filtered over Celite, and the organic layer is isolated. The ether is removed at reduced pressure and the resultant brown residue is boiled sequentially with six 50-mL portions of hexane (Note 7). The hot liquid is carefully decanted, leaving behind most of the dark residue. The yellow-to-colorless solid is crystallized from hot hexane (or methanol) to yield 5.6–6.2 g (71–80%) of colorless needles, mp 80–81°C (Note 8).