Reaction Steps
A solution of n-butyl lithium (6 mmole) was added dropwise to an E/Z (1:1) isomeric mixture of 3-(3-bromo-10,11-dihydrodibenzo[a,d]cyclohepten-5-ylidene)-N,N-dimethylpropylamine (1.98 g., 5.6 mmole) in 100 ml. dry tetrahydrofuran at -70° C. under a nitrogen atmosphere. After the yellowish orange solution was stirred at -70° C. for an additional 10 minutes, gaseous carbon dioxide was bubbled through the reaction medium for 30 min. to give a pale yellow solution. The reaction mixture was allowed to warm gradually to room temperature, and was then concentrated under reduced pressure. The residue was dissolved in water, and then the solution was neutralized with 1N hydrochloric acid. The crude E/Z (1:1) mixture was chromatographed on a reverse phase PRP-1 semi-preparative column with 15% acetonitrile in water to give 0.05 g. of the E-isomer and 0.08 g. of the Z-isomer. Both isomers were obtained as lyophilized powders, without definitive melting points. Rechromatography of the resulting isomeric mixture (0.8 g.) yielded more pure E-isomer (0.09 g.), Z-isomer (0.16 g.) and also an E/Z (1:1) isomeric mixture (0.10 g). pmr (E-isomer) (DMSO/d6) δ: 7.79 (d, J=1.6 Hz, 1H, H4), 7.68 (dd, J=7.9, 1.6 Hz, 1H, H2), 7.12-7.29 (m, 5H, aromatic), 5.88 (t, J=7.2 Hz, 1H, CH=), 3.30 (m, 2H, CH2Ar), 2.85 (m, 2H, CH2Ar), 2.35-2.45 (m, 4H, NCH2CH 2), 2.10 (s, 6H, NMe2). pmr (Z-isomer) (DMSO/d6) δ: 7.78 (dd, J=7.8, 1.7 Hz, 1H, H2), 7.66 (d, J=1.5 Hz, 1H, H4), 7.36 (d, J=7.8 Hz, 1H, H1), 7.04-7.26 (m, 4H, aromatic), 5.86 (t, J=7.2 Hz, 1H, CH=), 3.32 (m, 2H, CH2Ar), 2.85, (m, 2H, CH2Ar), 2.10-2.44 (m, 4H, NCH2CH2), 2.07 (s, 6H, NMe2).
