Beilstein J. Org. Chem. 2014, 10, 2270–2278.
Experimental
solvent was evaporated, the product was washed with diethyl
General procedure for the synthesis of diketones: A solution ether and hexane and dried.
of carboxylic acid (1 mmol), ketone (1 mmol, if required) and
TFAA (0.85 mL, 6 mmol) in dichloromethane (1 mL) was 1-Hydroxy-4-aza-2,3-dihydrofluorene hydrochloride (4a):
stirred for 15 min at rt. The required quantity of triflic acid Obtained from diketone 3u (299 mg, 1 mmol) in 95% (210 mg)
(usually 44 μL, 0.5 mmol) was then added, and the resulting yield as a brown solid. Mp 110–112 °С; 1H NMR (400 MHz,
solution was stirred at rt for 1–4 h (24 h for 3v and 3w) under methanol-d4) δ 7.97 (d, J = 7.8 Hz, HAr, 1H), 7.69 (t, J = 7.5
the conditions indicated in Scheme 1, Scheme 2, Table 1, and Hz, HAr, 1H), 7.59 (d, J = 7.7 Hz, HAr, 1H), 7.56 (t, J = 7.5 Hz,
Table 2 (TLC monitoring). The reaction mixture was evapo- HAr, 1H), 3.99 (t, J = 8.5 Hz, CH2, 2H), 3.79 (s, CH2, 2H), 2.91
rated under reduced pressure, and after quenching with water, (t, J = 8.5 Hz, CH2, 2H); 13С NMR (100 MHz, methanol-d4) δ
the residue was redissolved in dichloromethane (10 mL), 173.7 (C), 173.2 (C), 149.5 (C), 135.1 (CH), 132.0 (C), 127.4
washed with 5% NaHCO3 (2 × 3 mL), water (2 × 3 mL), and (CH), 126.1 (CH), 123.8 (CH), 105.9 (C), 41.1 (CH2), 30.7
dried over MgSO4. The solvent was removed in vacuum, and (CH2), 27.3 (CH2); Anal. calcd for C12H11NO·HCl: C, 65.02;
the crude reaction mixture was purified by silica gel chromatog- H, 5.46; N, 6.32; found: C, 64.72; H, 5.61; N, 6.24.
raphy (n-hexane/CH2Cl2/MeOH).
1,3-Bis(diphenylphosphoryl)acetone (5): A solution of
As illustrative examples, compounds 3a and 3c are prepared as diphenylphosphorylacetic acid (260 mg, 1 mmol) in a mixture
follows.
of TFAA (1.95 mL, 13.8 mmol) and TfOH (0.05 mL,
0.57 mmol) was kept at 60–65 °C for 1.5 h. The solvent was
2-(3-Phenylpropionyl)-1-indanone (3a): Obtained from evaporated under reduced pressure, the obtained residue was
β-phenylpropionic acid (1a, 150 mg, 1 mmol), TFAA (0.85 mL, stirred in a water (4 mL)/EtOH (4 mL) solution under reflux for
6 mmol) and TfOH (44 μL, 0.5 mmol) in 75% (100 mg) yield 2 h, cooled and concentrated. The residue was adjusted to pH
as a red solid. Mp 65–66 °C (Lit. [29]: mp 68–69 °C); 1H NMR 7.5 with 1 N NaHCO3, the solid formed was filtered, washed
(400 MHz, CDCl3) keto-enol (20:80); enol tautomer: δ 7.80 (d, with water, and dried. The product was purified by column
J = 7.6 MHz, HAr, 1H), 7.55–7.33 (m, HAr, 3H), 7.32–7.15 (m, chromatography (eluent: CH2Cl2/MeOH 50:1). Yield: 44%
HAr, 5H), 3.40 (s, CH2Ind, 2H), 3.04 (t, J = 7.7 Hz, CH2, 2H), (101 mg), white solid; mp 173–175 °С (Lit. [30]: mp
2.73 (t, J = 7.7 Hz, CH2, 2H); 13С NMR (100 MHz, CDCl3) δ 175–176 °C); 1H NMR (400 MHz, CDCl3) δ 7.80–7.68 (m,
191.1 (CO), 179.7 (C=C(OH)), 147.4 (CAr), 140.6 (CAr), 138.1 HAr, 8H), 7.57–7.41 (m, HAr, 12H), 3.97 (d, J = 14.3 Hz, CH2,
(CAr), 132.7 (CAr), 128.5 (CHAr), 128.3 (CHAr), 127.2 (CHAr), 4H); 13С NMR (100 MHz, CDCl3) δ 195.6 (CO), 132.2 (CHAr),
126.3 (CHAr), 125.6 (CHAr), 123.0 (CHAr), 110.5 (C=C(OH)), 131.2 (CAr), 130.9 (d, J = 10.6 Hz, CHAr,), 128.7 (CHAr, J =
36.8 (CH2), 31.6 (CH2), 29.9 (CH2).
12.7 Hz), 48.2 (d, J = 55.7, CH2, Hz); 31P NMR (CDCl3) δ
27.1.
2-[2-(1-Adamantyl)acetyl]-1-indanone (3c): Obtained from
1-adamantylacetic acid (1d, 194 mg, 1 mmol), 1-indanone (2a, The synthesis of pyrazoles 6. As an illustrative example, com-
132 mg, 1 mmol), TFAA (0.85 mL, 6 mmol) and TfOH (44 μL, pound 6a is prepared as follows. A solution of β-phenylpropi-
0.5 mmol) in 79% (240 mg) yield as a red solid. Mp 154 °C; onic acid (1a, 150 mg, 1 mmol) and TFAA (0.85 mL, 6 mmol)
1H NMR (400 MHz, CDCl3) keto-enol (2:98), enol tautomer: δ in 1 mL CH2Cl2 was stirred for 15 min at rt. Then TfOH
7.81 (d, J = 7.6 Hz, HAr, 1H), 7.52 (t, J = 7.4 Hz, HAr, 1H), (44 μL, 0.5 mmol) was added, and the reaction mixture was
7.46 (d, J = 7.5 Hz, HAr, 1H), 7.38 (t, J = 7.4 Hz, HAr, 1H), kept for 2 h. On completion of the reaction, the solvent was
3.58 (s, CH2Ind, 2H), 2.18 (s, CH2Ad, 2H), 1.98 (bs, CHAd, removed under reduced pressure. The crude 3a was dissolved in
3H,), 1.75–1.59 (m, CH2Ad, 12H); 13С NMR (100 MHz, 5 mL ethanol and heated under reflux with hydrazine hydrate
CDCl3) δ 193.6 (CO), 177.1 (C=C(OH)), 148.0 (CAr), 138.5 (0.1 mL, 2 mmol). After 2 h the solvent was evaporated, and the
(CAr), 132.9 (CHAr), 127.2 (CHAr), 125.6 (CHAr), 123.2 remaining oil was dissolved in CH2Cl2, washed with 5%
(CHAr), 111.7 (C=C(OH)), 48.6 (CH2Ad), 43.0 (CH2Ad), 36.7 NaHCO3, water, and dried over MgSO4. The product was puri-
(CH2Ad), 35.1 (CAd), 30.7 (CH2), 28.7 (CHAd); Anal. calcd for fied by means of column chromatography (SiO2 60, eluent:
C21H24O2: C, 81.78; H, 7.84; found: C, 82.23; H 7.67.
CH2Cl2/MeOH 50:1). Yield: 69% (90 mg), brown solid; mp
108–110 °С; 1H NMR (400 MHz, CDCl3) δ 7.71 (d, J = 7.2 Hz,
Typical procedure for the synthesis of heterocycles 4a,b: A HAr, 1H), 7.44 (d, J = 7.2 Hz, HAr, 1H), 7.40–7.17 (m, HAr,
solution of diketone 3u or 3v (1 mmol) in an ethanol (20 mL)/ 4H), 7.14 (d, J = 6.8 Hz, HAr, 2H), 3.42 (s, CH2, 2H), 3.04 (m,
water (4 mL)/HClconc (4 mL) mixture was heated under reflux CH2, 4H); 13С NMR (100 MHz, CDCl3) δ 148.7 (C), 140.8 (C),
for 6 h. After the reaction was completed (TLC control) the 137.9 (C), 134.7 (C), 128.5 (CH), 128.4 (CH), 126.4 (2CH),
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