“…shown by nmr to be mostly the trans isomer 2. Distillation of this was attended by considerable decomposition and afforded only 2.0 g (5%) of írans-ethyl 3-(2'-carboxyethylthio)acrylate (2): bp 152°( 0.8 mm); n25n 1.5319; ir (liquid film) 5.87, 6.33, 7.67, 10.6 µ; nmr (A-60, CDC13) 1.26 (t, 3 H, J = 7 Hz, -OCH2CH3), 2.94 (symmetrical multiplet, 4 H, -SCH2CH2-OOOH), 4.17 (q,2H,7 = 7 Hz, -OCH2CH3), 5.75 (d, 1 H, J = 15 Hz, =CHCOOEt), 7.67 (d, 1 H, J = 15 Hz, -SCH=); uv ®°278 nm(e 18,300). cis-3-(2'-Carboxyethylthio)acrylic Acid (3).-Propiolic acid (2.0 g, 29 mmol) and 3-mercaptopropionic acid (3.03 g, 29 mmol) were dissolved in an EtOH-water (1:3) mixture (50 ml) containing KOH (3.2 g, 58 mmol).…”