, NHC) catalysis Since their isolation as stable free carbenes by Arduengo in 1991, p.18
, J. Am. Chem. Soc, vol.113, p.361, 1991.
, Angew. Chem. Int. Ed, vol.510, p.3612, 2008.
, Select reviews, vol.107, p.9307, 2007.
, J. Am. Chem. Soc, p.13628, 2009.
, (b) Grossmann A.; Enders D, Angew. Chem. Int. Ed, vol.2, p.1832, 2010.
, Eur. J. Org. Chem, vol.131, p.4298, 1835.
, Cór dova, A. Chem. Eur. J, vol.17, p.1310, 2011.
, Angew. Chem. Int. Ed, vol.52, p.2311, 2013.
, Inspired by Danishefsky's work, improved synthetic routes to quadrone (I) and other Compound a: R f (average) = 0, PE:EtOAc =, vol.35, issue.1
, , p.52
, Tert-butyl acrylate b in the reaction crude: 13 C NMR (75 MHz, ? ppm/CD 2 Cl 2 ): 165.7 (C), 130.8 (CH), vol.129
,
, , p.239
, 75 MHz, ? ppm/ Pyridine-d 5 ): 3 dias
, C), 57.0 (C), 55.8 (C, 177.8 (C), 176.4 (C), 176.1(C), 175.5 (C), vol.54, p.36
, dias: 11.25 (br. s, 2H×3), 3.76 -2.85 (m, 3H×3, vol.18, p.3
, 3H), 0.98 (d, J = 6.2 Hz, 3H)
, Mazet's group according to the above reaction condition. 13 C NMR (100 MHz
, 175.5 (C), 60.6 (C), vol.51, pp.201-210
, , p.61
, CH 3 ). 1 H NMR (300 MHz, ? ppm/ CDCl 3 ): axial-Me: 5.98 -5.82 (m, 1H), 5.10 (t, J = 15.1 Hz, 2H), 3.66 (s, 3H), vol.22, p.33
, Hz, 1H), 1.56 (dt, J = 12, vol.9
, dr Me ax :Me eq ) in THF (1.9 mL, 0.05 M) was added N,N'-thiocarbonyldiimidazole (80.2 mg, 0.45 mmol) and potassium hydride (36.1 mg, 0.9 mmol). The reaction was stirred under reflux and argon atmosphere. After 12h, the reaction mixture was poured into saturated aqueous NH 4 Cl, and then dried over Na 2 SO 4, vol.1
, PE:EtOAc = 7:3). MS (ESI+, p.399
, 92.5 (C), vol.42, pp.33-39
, CH 3 ); 1 H NMR (300 MHz, ppm/ ? CDCl3): 8.18 (s, 1H), vol.32
, 3 µL, of THF and acetonitrile (5 mL, v : v = 1:1) was added trimethylsilyldiazomethane (230 µL, 2.0 M in hexane) at 0 o C, then the reaction solution was allowed to warm to room temperature and stirred for 10h to give diazoketone 63 (40.4 mg, 75%), Crude acid 62 was subjected to benzene (5 mL, 0.05 M), and then oxalyl chloride, p.75
, CDCl 3 ): axial-Me: 217.3 (C), 194.1 (C), 64.1 (C), vol.58
, 218.1 (C), 191.6 (C), 66.5 (C), 57.8 (CH), vol.55, p.30
, 2.25 (d, J = 14.1 Hz, 1H), 2.03 -1.80 (m, 3H), 1.71 (d, J = 14.4 Hz, 1H), 1.63 -1.22 (m, 2H), 1.16 (s, 3H), 0.91 (s, 3H), 0.88 (d, J = 7.1 Hz, 3H), axial-Me: 6.06 (s, 1H), 2.84 -2.76 (m, 1H)
, 17 mmol) in dioxane (3.5 mL, 0.05 M) was added H 2 O (61 µL, 3.4 mmol) and silver benzoate (7.8 mg, 0.034 mmol). The reaction mixture was stirred at 80 o C for 10h. Then, the reaction solution was extracted with diethyl ether, dried over Na 2 SO 4 and concentrated in vacuum. Purification by flash chromatography afforded compound 64 (27.5 mg, 72 %, 1:2 dr) as a white solid
, ? ppm/ CDCl 3 ): axial-Me: 215.6 (C), 209.2 (C), vol.66, pp.28-35
,
, 3H). of THF and acetonitrile (12.9 mL, v:v = 1:1, 0.05 M) was added trimethylsilyldiazomethane (650 µL, 2.0 M in hexane) at 0 o C, then the reaction solution was allowed to warm to room temperature and stirred for 10h to give diazoketone 67 (148.5 mg, 70%) as a yellowish oil, p, J = 6.9 Hz, 1H), 2.08-2.01 (m, 2H), 1.83 (d, J = 13.8 Hz, 1H), 1.82-1.79 (m, 1H), 1.67 (d, J = 13.7 Hz, 1H), 1.45-1.36 (m, 2H), vol.25, p.1
, 200.3 (C), 138.8 (C), 128.5 (CH×2), 127.5 (CH), 127.4 (CH×2), vol.81
, 58.8 (C), vol.53
, Hz, 1H). 1.93-1.84 (m, 3H), 1.76 -1.74 (m, 1H), 1.54 (d, J = 13.9 Hz, 1H), 1.48 (d, J ppm/CDCl 3 ): 7.18-7.30 (m, 5H), vol.25, p.25
, Hz, 1H), 1.40 -1.36 (m, 1H), vol.1
, 10 % Pd loading), then bubbled H 2 for 2 minutes. The reaction was stirred vigorously under hydrogen atmosphere (1.0 atm.) at room temperature. After 5 hours, the reaction reached full conversion. Pd/C was filtered, and the filtrate was concentrated in vacuum. Purification by flash chromatography afforded compound 70 (57.5 mg, 90 %) as yellow oil, MeOH was added Pd/C (30.9 mg, 0.029 mmol
, EtOH absolute ). 13 C NMR (75 MHz, pp.78-81
, Hz, 1H), 2.55 (br. s, 1H), 2.43 (d, J = 16.3 Hz, 1H), 2.15 (s, 3H, J =, vol.16, issue.3
, 3H), 1.09 (s, 3H), 1.03 (s, 3H)
, J =, vol.17, issue.9
, Hz, 1H), 2.10 ? 1.95 (m, 2H), vol.1
,
, LDA was prepared by adding n-BuLi (172 µL, 0.28 mmol, 1.6 M in hexanes) to a solution of diisopropylamine (43 µL, 0.31 mmol) in 5 mL of THF, at -78 °C. The solution was stirred 30
, EtOH absolute ). 13 C NMR (75 MHz, ? ppm/ CDCl 3 ): 214.8 (C), 191.1 (C), 119.7 (CH), 57.8 (C), vol.49, pp.39-45
, Pd/C was filtered, and the filtrate was concentrated in vacuum to afford IV, vol.42
, >99 %) without purification as a colorless oil which is not UV active and is not visible even though soaked by stains. HRMS (ESI+) for C 15 H 24 NaO + : calcd
, heptane/tertiobutanol (98/2), 1.0 mL/min, CD 290 nm): ? axial-Me = 8.56 min. 13 C NMR, p.100
, 220.4 (C), 57.0 (C), 50.1 (CH), 49.8 (CH), vol.47
, Hz, 1H), 1.88 (p, J = 7.2 Hz, 1H), 1.75 (br. t, J = 3.1 Hz, 1H), 1.70 -1.55 (m, 2H), vol.1
, Table 3: the comparison of 1 H chemical shifts of (+)-suberosanone 2.32 (m, 4H)
,
, Hz, 3H) 1.03 (d, J = 7.0 Hz, p.3
, Hz, 1H) 1.88 (p, J = 7.2 Hz, 1H), p.89
, 130, 14416; 2) Konishi, H.; Rawal, V, J. Am. Chem. Soc, p.12, 2008.
, Org. Lett, vol.15, p.6090, 2013.
, Adv. Synth. Catal, vol.354, p.3523, 2012.
, To a solution of ?-substituted-?-oxocyclobutanecarboxamides (50 mg, 0.13 mmol) in DCM
, 1456, found: 401.1456; HPLC (Chiralpak IC, heptane/ethanol (50/50), 1.0 mL/min, DAD): ? major = 6.43 and 8.16 min, ? minor = 7.03 and 9, pp.140-149
, 171.1 (C), 147.7 (C), 139.4 (C), 136.1 (C), vol.128
, H NMR (300 MHz, ? ppm/CDCl 3 ): major dia: 8.22 (d, J = 8.5 Hz, 2H), 7.29 -7.08 (m, 7H), 5.09 (td, J = 13.7, 7.4 Hz, 1H), vol.21
, Hz, 1H), 4.95 (dd, J = 13.1, 7.9 Hz, 1H), 4.13 -3.98 (m, 1H), 3.13 -3.06 (m, 1H)