Response of acidity and magnetic resonance properties to aryl substitution in carbon acids and derived carbanions: 1-aryl-4-phenylcyclopenta-1,3 dienes. Dependence of ionic structure on aryl substitution

Abstract

Eine z.B. p‐Substitution durch Halogen bzw. eine Methyl‐, Methoxy‐ oder Methylthiogruppe führt zu einer Abhängigkeit von 1H‐ und 13C‐NMR‐Daten sowie der pKa‐Werte in.

Synthesis of a Tetraphenyl-Substituted Dihydropentalene and Its Alkali Metal Hydropentalenide and Pentalenide Complexes

“…We thus investigated the use of stronger bases to generate more of the 1,4-Ph 2 Cp − nucleophile in situ. With the pK a of 1,4-Ph 2 CpH reported as 14.3, 35 in 53% isolated yield. As this did not provide an improvement over NaOMe or pyrrolidine, we conclude that stronger bases do not necessarily increase the efficiency of this annulation reaction (Figure 2), and success is equally dependent on the correct choice of reaction solvent (Table 1).…”

“…We thus investigated the use of stronger bases to generate more of the 1,4-Ph 2 Cp – nucleophile in situ. With the p K a of 1,4-Ph 2 CpH reported as 14.3, sodium methoxide (p K a = 15.5) in MeOH was used to activate 1,4-Ph 2 CpH followed by the addition of 1,3-diphenylprop-2-en-1-one. After heating to 70 °C for 40 h a 65% yield of 1,3,4,6-Ph 4 PnH 2 was obtained.…”

“…As previously reported. 35 1,3,4,6-Tetraphenyl-1,2-dihydropentalene. 1,4-Diphenyl-1,3cyclopentadiene (1.00 g, 4.58 mmol) and 1,3-diphenylprop-2-en-1one (1.05 g, 5.04 mmol) were dissolved in 20 mL dry methanol and 20 mL dry toluene.…”

“…Quantitative 1 H NMR analysis in DMSO-d 6 showed the compound to be Li-[PnHPh 4 ]•THF 0.5 (73% yield). J HH = 7.28 Hz, 1H, p-Ph), 6.63 (m, 1H, p-Ph, H c ), 5.90, (d,3 J HH = 1.57 Hz, 1H, H b ), 4.71 (d,3 J HH = 1.57 Hz, 1H, H a ); 1 H NMR (500 MHz, DMSO-d 6 ) δ 7.28−7.22 (m, 6H, Ph), 7.13−7.09 (m, 5H, Ph), 7.00 (t,3 J HH = 7 35. Hz, 1H Ph), 6.92 (d,3 J HH = 7.72 Hz, 2H, Ph), 6.86 (t,3 J HH = 7.72 Hz, 2H, Ph), 6.81 (t,3 J HH = 7.60 Hz, 2H, Ph), 6.63 (t,3 J HH = 7.20 Hz, 1H, Ph), 6.51 (t,3 J HH = 7.20 Hz, 1H, Ph), 6.30 (s, 1H, H c ), 5.65 (d,3 J HH = 2 23.…”

Thiophene/cyclopentadiene regular copolymers from electrochemical oxidation of dithienylcyclopentadienes

“…This route is a modification of the synthesis of 1,4-diphenyl-1,3-cyclopentadienes reported in the literature. [12] Electrochemical and absorbance data for the monomers are shown in Table 1). …”