4,9-Methano[11]annulenylidene. Example of a ten-.pi.-electron carbocyclic aromatic carbene

Synthesis and photolysis of 2-acylpyrazolidin-3-ones. Model for the photochemical syntheses of 6-azapenicillin isomers

“…Heating of the mixture (110°for 3 hr) followed by recrystallization of the crude product from El^O resulted in a 60% yield (based on 2) of pure 4e: mp 74-75°; ir (CCI4) 2960, 1750 (broad), 1450, 1410, 1390, 1380, 1340, 1225, 1205, 1125, 1095, 1055 cm"1; NMR (CCI3D) 1.52 (s, 6), 2.65 (s, 2), 4.28 (s, 2), 4.75 (s, 2), 7.29 (s, 5); mass spectrum (70 eV) m/e (rel intensity) no parent ion, 308 (2), 288 (5, 3-C1), 273 (3, 3-C1), 253 (1), 204 (2), 203 (3), 159 (2), 141 (8), 136 (24), 131 (12, 3-C1), 119 (25), 105 Anal. Caled for C16H17N2O4CI3: C, 47.14; , 4.20; N, 6.87.…”

“…Pyrazoline 3f was prepared in 70% yield in a manner similar to that described for the preparation of 3a. For 3f: mp 124-125°ir (CCU 3050, 2960(CCU 3050, (shoulder 2940(CCU 3050, ), 1755(CCU 3050, , 1720(CCU 3050, , 1425(CCU 3050, , 1325(CCU 3050, , 1250(CCU 3050, (shoulder 1240(CCU 3050, ), 1210(CCU 3050, , 1175(CCU 3050, , 1110(CCU 3050, , 1075(CCU 3050, , 1055(CCU 3050, , 1020, 960 cm*1; NMR (CC13D) 1.72 (s, 6), 3.28 (s, 2), 4.91 (s, 2), 7.50-7.80 (m, 3), 8.05-8.30 (m, 2); mass spectrum (70 eV) m/e (rel intensity) 392 (1, 3-C1, M+), 357 (0.5, 2-C1), 288 (0.5, 3-C1) 273 (trace, 3-C1), 245 (1.5), 266 (trace), 218 (trace), 307 (0.7), 198 (trace), 159 (trace), 141 (0.8), 133 (1), 131 (1), 122 (2.5), 113 (1.5) 106 ( 8), 105 (100), 99 (0.5), 97 (1), 95 (1.5), 86 (1), 83 (4), 78 (1.5), 72 (24), 71 (1), 61 (1.2), 56 (4), 55 (2.5), 51 (5), 50 (1), 43 (2), 42 (2.5), 41 (3).…”