The kinetics of intramolecular meisenheimer complex cyclizations to bicyclic dinitropropenide anions. A mechanism for the reaction

Electroreduction of .alpha.,.beta.-unsaturated esters. II. Syntheses of 2,3-diaryl-5-oxocyclopentane-1-carboxylates by hydrodimerization of cinnamates

“…Pmr analysis of effluents a and b indicated that only aliphatic protons were present. Rotary evaporation at 80°of combined effluents a and b to constant weight (compound 2 is volatile under these conditions) gave 2.02 g (49%, based on total 2 used) of diethyl 2-ethylidene-3-methylglutarate (7): ir (CHCls) 1640 (conjugated C=C), 1710, and 1730 cm-1 (ester C=0 groups); pmr (neat) 1.17 and 1.25 (2 overlapping t, superimposed on d, 9, 2 OCH2CH3 plus CH3CHCH2), 1.82 (d, 3, J = 7 Hz, =CHCH8), 2.58 and 2.62 (2 overlapping d, 2, J = 7-8 Hz, CH2C=0), 3.3 (m, 1, methinyl ), 4.05 and 4.15 (2 overlapping q, 4, / = 6-7 Hz, 2 OCH2CH3), 6.81 (q, 1, vinyl H); mass spectrum m/e (reí intensity) 228 (7, M+), 183 (90, M -C2H50), 182 (93), 155 (21), 154 (100), 140 (18), 126 (57), 125 (20), 113 (27), 112 (27), 95 (27), 81 (33), 69 (22), 67 (39), 53 (16). Saponification of 7 gave 2-ethylidene-3-methylglutaric acid as needles from benzene-hexane, mp 129-130°(lit.16 mp 129°).…”

“…Found: C, 55.79; , 7.09. From chromatographic effluent d was isolated 4d (31%). When this electroreduction experiment was repeated in exactly the same way except that the ethyl crotonate was only stirred with the catholyte (open circuit) for 23 min after re- (16) H. von Peohmann, Ser., 33, 3323 (1900).…”