(Z)-2-Methoxy-1-phenylthio-1,3-butadiene (CAS NO.: ), which is also known as , [(2-methoxy-1,3-butadienyl)thio]-, (Z)-, could be produced through the following synthesis routes.

A. Bis(phenylthio)methane (CAS NO.: ). A dry, 2-l., one-necked flask equipped with a magnetic stirring bar and a 250-ml., pressure-equalizing dropping funnel mounted with a combined inlet-outlet assembly for introducing argon is charged with 1.5 l. of distilled dichloromethane and 79.9 g. (110 ml., 0.791 mole) of , and purged with argon. The solution is stirred and cooled in an ice bath as 87 g. (81 ml., 0.79 mole) of thiophenol is added over 20–30 minutes. The mixture is allowed to warm to 20° and stirred at this temperature for another 3 hours. is removed by filtration through a fritted-glass Büchner funnel, and the filtrate is washed with two 200-ml. portions of 10% aqueous sodium hydroxide, two 200-ml. portions of 2 N hydrochloric acid, and one 300-ml. portion of . The dichloromethane solution is dried over anhydrous magnesium sulfate and evaporated under reduced pressure. Recrystallization of the residue from petroleum ether gives 51.2–59.6 g. (56–65%) of bis(phenylthio)methane as white crystals, m.p. 35–37°.

B. 4,4-Bis(phenylthio)-3-methoxy-1-butene (CAS NO.: 60466-65-1). A 250-ml., two-necked, round-bottomed flask equipped with a magnetic stirring bar, a rubber septum, and a reflux condenser bearing an inlet-outlet assembly for argon is dried in an oven at 110° and cooled under a stream of argon passed through the septum with a syringe needle and vented through the argon bubbler. A solution of 5.00 g. (0.0215 mole) of bis(phenylthio)methane in 150 ml. of tetrahydrofuran is placed in the flask and cooled to -20° with a carbon tetrachloride–dry ice bath. A 15.8-ml. (0.0217 mole) aliquot from a 1.37 M solution of n-butyllithium in hexane is injected through the septum with a syringe. The resulting deep-yellow solution is stirred and cooled at -20° for 1 hour and then cooled to -78° with an acetone–dry ice bath. The color of the solution is discharged immediately when 1.4 g. (1.7 ml., 0.025 mole) of acrolein is added by syringe at -78°. Stirring and cooling are continued for 15 minutes, after which 2.90 g. (2.19 ml., 0.0230 mole) of dimethyl sulfate is added, and the cooling bath is removed. The solution is stirred at room temperature for 16 hours and heated at reflux for 2 hours. A 3-ml. portion of water is added to the cooled mixture, most of the tetrahydrofuran is removed by rotary evaporation, and the concentrate is partitioned between 30 ml. of water and 30 ml. of diethyl ether. The organic layer is washed three times with 10-ml. portions of concentrated ammonia and once with water. The ethereal solution is dried over anhydrous magnesium sulfate and evaporated under reduced pressure. Crystallization of the viscous yellow residue from 30 ml. of 95% ethanol at -20° gives 3.11–3.36 g. (48–52%) of 4,4-bis(phenylthio)-3-methoxy-1-butene as a light-yellow solid, m.p. 45–48°, which is of adequate purity for use in the next step.

C. (Z)-2-Methoxy-1-phenylthio-1,3-butadiene (CAS NO.: ). A 250-ml., two-necked, round-bottomed flask equipped with a magnetic stirring bar, a rubber septum, and a reflux condenser bearing a combined inlet-outlet assembly for argon is flushed with argon and charged with 3.27 g. [0.00650 mole, 0.0126 g.-atom of copper(I)] of bis[copper(I) trifluoromethanesulfonate] benzene complex, 0.036 g. (0.18 mmole) of 3-tert-butyl-4-hydroxy-5-methylphenyl sulfide, and 70 ml. of benzene. With syringes 1.20 g. (0.00397 mole) of 4,4-bis(phenylthio)-3-methoxy-1-butene, 1.33 g. (1.80 ml., 0.0103 mole) of N,N-diisopropylethylamine, and 14 ml. of tetrahydrofuran are injected through the septum into the flask. The suspension is stirred and heated under reflux for 4.75 hours, after which the starting thioacetal has completely reacted, as judged by TLC. Water (2 ml.) is added to the cooled mixture, the insoluble material is removed by filtration through Celite, and the flask is rinsed with several portions of ether. A 40-ml. portion of water is added to the filtrate, the layers are separated, and the aqueous layer is extracted with three 25-ml. portions of ether. The organic solutions are combined, dried over anhydrous magnesium sulfate, and evaporated under reduced pressure. Bulb-to-bulb distillation of the residual brown oil (0.782 g.) in a Kugelrohr apparatus with an oven temperature of 85–95° (0.005 mm.) provides 0.421–0.486 g. (55–64%) of (Z)-2-methoxy-1-phenylthio-1,3-butadiene as a light-yellow oil.

Notice: Part A should be carried out in an efficient hood to minimize exposure to the foul-smelling thiophenol. Benzene has been identified as a carcinogen; OSHA has issued emergency standards on its use. All procedures involving benzene should be carried out in a well-ventilated hood, and glove protection is required.