C, 64.70; H, 3.95. Found: C, 64.35; H, 3.80. a-(Z)-(Tetrahydrofuran-2-ylidene)-y- butyrolactone (23). The reaction of 1 (0.03 mol) and 7-butyrolactone (21)(2.58 g, 0.03 mol) in 50 mL of benzene at 150" C for 8 h in a sealed tube gave 1.42 g (31%) of 23: mp 81-82 OC (from benzene-hexane)(lit. 16 mp 86.5" C); IR (Nujol) 1740 (M) and 1650 cm-'(C= C); NMR (CDC13) 8 1.85-2.39 (m, 2 H, methylene protons), 2.70-3.30 [m, 4 H, C= C (-O-) CH2+ C= ...