Efficient synthesis of selected indenones

Cationic Gold‐Catalyzed Intramolecular Cyclization of Substituted 1,5‐Diynes to Access Indenone Derivatives

“…NMR (500 MHz, CDCl 3 ) δ 7.94-7.90 (m, 2H), 7.59 (d, J = 7.1 Hz, 1H), 7.53 (dd, J = 9.8, 5.0 Hz, 2H), 7.39-7.30 (m, 5H), 7.02 (d, J = 7.3 Hz, 1H), 6.71-6.65 (m, 2H), 5.04 (s, 1H) ppm; 13 C{ 1 H}NMR (100 MHz, CDCl 3 ) δ 194. 86, 194.36, 168.19, 156.91, 145.84, 136.02, 135.08, 134.47, 134.12, 131.40, 129.43, 128.88, 125.82, 125.72, 125.38, 125.06, 121.97, 115.55, 114.81, 114.58, 110.66, 110.40…”

“…of N-oxide, 9 mg (5 mol %) of AuClPPh 3 and 14 mg (10 mol %) of AgNTf 2 the reaction time was 3 hours at 28 °C. After flash column chromatography on silica gel (eluted with R f : 0.5; hexane/ethyl acetate mixture 10/0.1); 91 mg of 2 h was obtained in 86% yield as a orange solid; Mp: 365-367 °C; 1 H NMR (400 MHz, CDCl 3 ) δ 7.55 (d, J = 7.1 Hz, 1H), 7.39 (t, J = 7.2 Hz, 1H), 7.32 (d, J = 8.6 Hz, 2H), 7.28-7.22 (m, 2H), 6.90 (d, J = 8.6 Hz, 2H), 5.99 (s, 1H), 2.48 (t, J = 7.2 Hz, 2H), 1.62 (dd, J = 14.7, 7.3 Hz, 2H), 0.84 (t, J = 7.4 Hz, 3H) ppm; 13 C{ 1 H}NMR (100 MHz, CDCl 3 ) δ 204. 83, 197.17, 157.17, 149.13, 143.50, 134.84, 134.45, 134.24, 134.11, 131.14, 129.54, 129.33, 129.22, 129.00, 124.02, 122.23, 121.76, 115.81, 44.47, 17.44, 13.63…”

“…of N-oxide, 7 mg (5 mol %) of AuClPPh 3 and 11 mg (10 mol %) of AgNTf 2 the reaction time was 3 hours at 28 °C. After flash column chromatography on silica gel (eluted with R f : 0.5; hexane/ethyl acetate mixture 10/0.1); 83 mg of 2 l was obtained in 80% yield as a orange solid; Mp: 265-267 °C; 1 H NMR (500 MHz, CDCl 3 ) δ 7.83 (d,J = 8.2 Hz,2H),7.49 (d,J = 7.4 Hz,1H),2H),7.16 (d,J = 8.0 Hz,2H),1H),6.82 (d,J = 0.7 Hz,1H),2H),5.61 (s,1H), 2.58 (q, J = 7.6 Hz, 2H), 2.35 (s, 3H), 1.17 (t, J = 7.6 Hz, 3H) ppm; 13 C{ 1 H}NMR (100 MHz, CDCl 3 ) δ 196. 44, 194.92, 156.42, 152.05, 148.63, 145.69, 144.90, 134.32, 132.79, 131.04, 129.64, 127.92, 127.44, 124.04, 122.55, 121.63, 115.50, 29.40, 21.88, 15.16:;IR (KBr): ν 3316, 2875, 1714, 1604, 1231 12) Å, V = 3870.3(2) Å 3 , Z = 8, T = 294.15 K, μ(Mo Kα) = 0.082 mm À 1 , Dcalc = 1.265 g/cm 3 , 16749 reflections measured (4.32°� 2Θ � 50°), 3398 unique (R int = 0.3913, R sigma = 0.3905) which were used in all calculations.…”

“…After flash column chromatography on silica gel (eluted with R f : 0.5; hexane/ethyl acetate mixture 10/0.1); 91 mg of 2 q was obtained in 82% yield as a yellow solid; Mp: 113-115 °C; 1 H NMR (400 MHz, CDCl 3 ) δ 7. 96-7.90 (m, 2H), 7.65-7.59 (m, 1H), 7.56-7.51 (m, 1H), 7.45-7.34 (m, 4H), 7.34-7.27 (m, 1H), 7.25-7.20 (m, 2H), 7.08-6.98 (m, 2H), 6.96-6.89 (m, 1H) ppm; 13 C{ 1 H}NMR (100 MHz, CDCl 3 ) δ 196. 08, 194.64, 150.41, 144.11, 135.20, 134.71, 134.45, 134.42, 129.70, 129.60, 129.40, 129.02, 128.85, 128.35, 123.94, 121.81.…”

“…[10] Different methods were reported for synthesis of indenones via aldol condensation, [11] 1,3-diaryl propynones cyclization, [12] Friedel-Crafts acylation. [13] And also synthetic protocols were reported by employing metals such as rhodium, [14] ruthenium, [15] palladium, [16a,b] and copper. [17] Visible light promoted reaction was developed by Reizer et al, to access the indenone derivatives from o-alkylated -α-bromocinnamates [Scheme 1 (i)].…”