Oxidoboron

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: (8) (Chem. Pharm. Bull. 1974, 22(2), 448-451). Boron oxide (720 mg, 10.26 mmol) and benzaldehyde (800 mg, 7.53 mmol) were added to a stirred solution of the indandione (1.00 g, 6.84 mmol) and piperidine (3 drops) in 10.2 ml of benzene. The solution was refluxed with stirring for 30 minutes. After filtration of the solution, the filtrate was concentrated under reduced pressure. The resulting crystalline solid was recrystallized from ethanol to afford 1.00 g (62.4%) of yellowish-green platelets: mp 149.5-150.0° C. (lit. mp 150° C., Okukawa, et al., Chem. Pharm. Bull., 1974, 22(2), 448-451). 1H NMR (250 MHz) δ 8.47-8.45 (m, 2 H), 8.06-7.99 (m, 2 H), 7.90 (s, 1 H), 7.84-7.79 (m, 2 H), 7.58-7.50 (m, 3 H); 13C NMR (62.7 MHz) 190.5, 189.2, 147.2, 142.7, 140.2, 135.6, 135.4, 134.3, 133.4, 133.2, 129.3, 129.0, 123.5, 123.5 ppm. The solution was refluxed After filtration of the solution the filtrate was concentrated under reduced pressure The resulting crystalline solid was recrystallized from ethanol to afford 1.00 g (62.4%) of yellowish-green platelets

Conditions: temp:70.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: In a 20 mL reaction vessel were placed 31.0 mg (136 μmol) of 6-(1H-indol-2-yl)hex-5-ene-2,4-dione and 13.2 mg (0.190 mmol) of boron oxide and they were dissolved in 0.88 mL of ethyl acetate. To the mixture under stirring at 70° C., 33 mg (0.14 mmol) of 2-methoxy-4-(4-pyridylmethoxy)benzaldehyde and 62 μL (0.27 mmol) of triisopropyl borate were sequentially added. After the mixture was stirred at the same temperature for 1 hour, a solution of 2.7 μL (27 μmol) of piperidine in ethyl acetate (0.135 mL) was added and the mixture was further stirred for 1 hour. To the reaction mixture was added a 1:1 solution (0.4 mL) of 1 N hydrochloric acid and saturated brine at room temperature and the mixture was stirred for 5 minutes to 1 hour (further, the mixture was neutralized with a saturated sodium bicarbonate aqueous solution as needed). The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol) to give 47.3 mg (78% yield) of the title compound as an orange powder. In a 20 mL reaction vessel After the mixture was stirred at the same temperature for 1 hour the mixture was further stirred for 1 hour the mixture was stirred for 5 minutes to 1 hour (further, the mixture The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol)

Conditions: temp:70.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: In a 20 mL reaction vessel were placed 88 mg (0.27 mmol) of 6-[2-methoxy-4-(4-pyridylmethoxy)phenyl]hex-5-ene-2,4-dione and 26.4 mg (0.380 mmol) of boron oxide and they were dissolved in 1.76 mL of ethyl acetate. To the mixture under stirring at 70° C., 40 mg (0.27 mmol) of 1H-indole-7-carboxaldehyde and 124 μL (0.54 mmol) of triisopropyl borate were sequentially added. After the mixture was stirred at the same temperature for 1 hour, a solution of 5.4 μL (54 μmol) of piperidine in ethyl acetate (0.27 mL) was added and the mixture was further stirred for 1 hour. To the reaction mixture was added a 1:1 solution (0.8 mL) of 1 N hydrochloric acid and saturated brine at room temperature and the mixture was stirred for 5 minutes to 1 hour (further, the mixture was neutralized with a saturated sodium bicarbonate aqueous solution as needed). The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol) to give 43.5 mg (36% yield) of the title compound as a yellow powder. In a 20 mL reaction vessel After the mixture was stirred at the same temperature for 1 hour the mixture was further stirred for 1 hour the mixture was stirred for 5 minutes to 1 hour (further, the mixture The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol)

Conditions: temp:70.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: In a 20 mL reaction vessel were placed 88 mg (0.27 mmol) of 6-[2-methoxy-4-(4-pyridylmethoxy)phenyl]hex-5-ene-2,4-dione and 26.4 mg (0.380 mmol) of boron oxide and they were dissolved in 1.76 mL of ethyl acetate. To the mixture under stirring at 70° C., 40 mg (0.27 mmol) of 1H-indole-7-carboxaldehyde and 124 μL (0.54 mmol) of triisopropyl borate were sequentially added. After the mixture was stirred at the same temperature for 1 hour, a solution of 5.4 μL (54 μmol) of piperidine in ethyl acetate (0.27 mL) was added and the mixture was further stirred for 1 hour. To the reaction mixture was added a 1:1 solution (0.8 mL) of 1 N hydrochloric acid and saturated brine at room temperature and the mixture was stirred for 5 minutes to 1 hour (further, the mixture was neutralized with a saturated sodium bicarbonate aqueous solution as needed). The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol) to give 43.5 mg (36% yield) of the title compound as a yellow powder. In a 20 mL reaction vessel After the mixture was stirred at the same temperature for 1 hour the mixture was further stirred for 1 hour the mixture was stirred for 5 minutes to 1 hour (further, the mixture The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol)

Conditions: temp:70.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: In a 20 mL reaction vessel were placed 88 mg (0.27 mmol) of 6-[2-methoxy-4-(3-pyridylmethoxy)phenyl]hex-5-ene-2,4-dione and 26.4 mg (0.380 mmol) of boron oxide and they were dissolved in 1.76 mL of ethyl acetate. To the mixture under stirring at 70° C., 40 mg (0.27 mmol) of 1H-indole-7-carboxaldehyde and 124 μL (0.54 mmol) of triisopropyl borate were sequentially added. After the mixture was stirred at the same temperature for 1 hour, a solution of 5.4 μL (54 μmol) of piperidine in ethyl acetate (0.27 mL) was added and the mixture was further stirred for 1 hour. To the reaction mixture was added a 1:1 solution (0.8 mL) of 1 N hydrochloric acid and saturated brine at room temperature and the mixture was stirred for 5 minutes to 1 hour (further, the mixture was neutralized with a saturated sodium bicarbonate aqueous solution as needed). The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol) to give 21.6 mg (18% yield) of the title compound as a yellow powder. In a 20 mL reaction vessel After the mixture was stirred at the same temperature for 1 hour the mixture was further stirred for 1 hour the mixture was stirred for 5 minutes to 1 hour (further, the mixture The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol)

Conditions: temp:70.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: In a 20 mL reaction vessel were placed 31.0 mg (136 μmol) of 6-(1H-indol-4-yl)hex-5-ene-2,4-dione and 13.2 mg (0.190 mmol) of boron oxide and they were dissolved in 0.88 mL of ethyl acetate. To the mixture under stirring at 70° C., 33 mg (0.14 mmol) of 2-methoxy-4-(3-pyridylmethoxy)benzaldehyde and 62 μL (0.27 mmol) of triisopropyl borate were sequentially added. After the mixture was stirred at the same temperature for 1 hour, a solution of 2.7 μL (27 μmol) of piperidine in ethyl acetate (0.135 mL) was added and the mixture was further stirred for 1 hour. To the reaction mixture was added a 1:1 solution (0.4 mL) of 1 N hydrochloric acid and saturated brine at room temperature and the mixture was stirred for 5 minutes to 1 hour (further, the mixture was neutralized with a saturated sodium bicarbonate aqueous solution as needed). The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol) to give 42.8 mg (70% yield) of the title compound as an orange powder. In a 20 mL reaction vessel After the mixture was stirred at the same temperature for 1 hour the mixture was further stirred for 1 hour the mixture was stirred for 5 minutes to 1 hour (further, the mixture The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol)

Conditions: temp:70.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: In a 20 mL reaction vessel were placed 31.0 mg (136 μmol) of 6-(1H-indol-4-yl)hex-5-ene-2,4-dione and 13.2 mg (0.190 mmol) of boron oxide and they were dissolved in 0.88 mL of ethyl acetate. To the mixture under stirring at 70° C., 33 mg (0.14 mmol) of 2-methoxy-4-(3-pyridylmethoxy)benzaldehyde and 62 μL (0.27 mmol) of triisopropyl borate were sequentially added. After the mixture was stirred at the same temperature for 1 hour, a solution of 2.7 μL (27 μmol) of piperidine in ethyl acetate (0.135 mL) was added and the mixture was further stirred for 1 hour. To the reaction mixture was added a 1:1 solution (0.4 mL) of 1 N hydrochloric acid and saturated brine at room temperature and the mixture was stirred for 5 minutes to 1 hour (further, the mixture was neutralized with a saturated sodium bicarbonate aqueous solution as needed). The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol) to give 42.8 mg (70% yield) of the title compound as an orange powder. In a 20 mL reaction vessel After the mixture was stirred at the same temperature for 1 hour the mixture was further stirred for 1 hour the mixture was stirred for 5 minutes to 1 hour (further, the mixture The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol)

Conditions: temp:70.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: In a 20 mL reaction vessel were placed 44.3 mg (136 μmol) of 6-[2-methoxy-4-(2-pyridylmethoxy)phenyl]hex-5-ene-2,4-dione and 13.2 mg (0.190 mmol) of boron oxide and they were dissolved in 0.88 mL of ethyl acetate. To the mixture under stirring at 70° C., 20 mg (0.14 mmol) of 1H-benzotriazole-5-carboxaldehyde and 62 μL (0.27 mmol) of triisopropyl borate were sequentially added. After the mixture was stirred at the same temperature for 1 hour, a solution of 2.7 μL (27 μmol) of piperidine in ethyl acetate (0.135 mL) was added and the mixture was further stirred for 1 hour. To the reaction mixture was added a 1:1 solution (0.4 mL) of 1 N hydrochloric acid and saturated brine at room temperature and the mixture was stirred for 5 minutes to 1 hour (further, the mixture was neutralized with a saturated sodium bicarbonate aqueous solution as needed). The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol) to give 5.9 mg (10% yield) of the title compound as an orange powder. In a 20 mL reaction vessel After the mixture was stirred at the same temperature for 1 hour the mixture was further stirred for 1 hour the mixture was stirred for 5 minutes to 1 hour (further, the mixture The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol)

Conditions: temp:70.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: In a 20 mL reaction vessel were placed 31.0 mg (136 μmol) of 6-(1H-indol-6-yl)hex-5-ene-2,4-dione and 13.2 mg (0.190 mmol) of boron oxide and they were dissolved in 0.88 mL of ethyl acetate. To the mixture under stirring at 70° C., 29 mg (0.14 mmol) of 4-(2-pyridylmethoxy)benzaldehyde and 62 μL (0.27 mmol) of triisopropyl borate were sequentially added. After the mixture was stirred at the same temperature for 1 hour, a solution of 2.7 μL (27 μmol) of piperidine in ethyl acetate (0.135 mL) was added and the mixture was further stirred for 1 hour. To the reaction mixture was added a 1:1 solution (0.4 mL) of 1 N hydrochloric acid and saturated brine at room temperature and the mixture was stirred for 5 minutes to 1 hour (further, the mixture was neutralized with a saturated sodium bicarbonate aqueous solution as needed). The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol) to give 41.3 mg (72% yield) of the title compound as a yellow powder. In a 20 mL reaction vessel After the mixture was stirred at the same temperature for 1 hour the mixture was further stirred for 1 hour the mixture was stirred for 5 minutes to 1 hour (further, the mixture The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol)

Conditions: temp:70.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: In a 20 mL reaction vessel were placed 31.0 mg (136 μmol) of 6-(1H-indol-3-yl)hex-5-ene-2,4-dione and 13.2 mg (0.190 mmol) of boron oxide and they were dissolved in 0.88 mL of ethyl acetate. To the mixture under stirring at 70° C., 29 mg (0.14 mmol) of 4-(2-pyridylmethoxy)benzaldehyde and 62 μL (0.27 mmol) of triisopropyl borate were sequentially added. After the mixture was stirred at the same temperature for 1 hour, a solution of 2.7 μL (27 μmol) of piperidine in ethyl acetate (0.135 mL) was added and the mixture was further stirred for 1 hour. To the reaction mixture was added a 1:1 solution (0.4 mL) of 1 N hydrochloric acid and saturated brine at room temperature and the mixture was stirred for 5 minutes to 1 hour (further, the mixture was neutralized with a saturated sodium bicarbonate aqueous solution as needed). The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol) to give 25.7 mg (45% yield) of the title compound as an orange powder. In a 20 mL reaction vessel After the mixture was stirred at the same temperature for 1 hour the mixture was further stirred for 1 hour the mixture was stirred for 5 minutes to 1 hour (further, the mixture The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol)

Conditions: temp:70.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: In a 20 mL reaction vessel were placed 31.0 mg (136 μmol) of 6-(1H-indol-3-yl)hex-5-ene-2,4-dione and 13.2 mg (0.190 mmol) of boron oxide and they were dissolved in 0.88 mL of ethyl acetate. To the mixture under stirring at 70° C., 29 mg (0.14 mmol) of 4-(2-pyridylmethoxy)benzaldehyde and 62 μL (0.27 mmol) of triisopropyl borate were sequentially added. After the mixture was stirred at the same temperature for 1 hour, a solution of 2.7 μL (27 μmol) of piperidine in ethyl acetate (0.135 mL) was added and the mixture was further stirred for 1 hour. To the reaction mixture was added a 1:1 solution (0.4 mL) of 1 N hydrochloric acid and saturated brine at room temperature and the mixture was stirred for 5 minutes to 1 hour (further, the mixture was neutralized with a saturated sodium bicarbonate aqueous solution as needed). The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol) to give 25.7 mg (45% yield) of the title compound as an orange powder. In a 20 mL reaction vessel After the mixture was stirred at the same temperature for 1 hour the mixture was further stirred for 1 hour the mixture was stirred for 5 minutes to 1 hour (further, the mixture The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol)

Conditions: temp:70.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: In a 20 mL reaction vessel were placed 31.0 mg (136 μmol) of 6-(1H-indol-5-yl)hex-5-ene-2,4-dione and 13.2 mg (0.190 mmol) of boron oxide and they were dissolved in 0.88 mL of ethyl acetate. To the mixture under stirring at 70° C., 29 mg (0.14 mmol) of 4-(2-pyridylmethoxy)benzaldehyde and 62 μL (0.27 mmol) of triisopropyl borate were sequentially added. After the mixture was stirred at the same temperature for 1 hour, a solution of 2.7 μL (27 μmol) of piperidine in ethyl acetate (0.135 mL) was added and the mixture was further stirred for 1 hour. To the reaction mixture was added a 1:1 solution (0.4 mL) of 1 N hydrochloric acid and saturated brine at room temperature and the mixture was stirred for 5 minutes to 1 hour (further, the mixture was neutralized with a saturated sodium bicarbonate aqueous solution as needed). The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol) to give 37.1 mg (65% yield) of the title compound as a yellow powder. In a 20 mL reaction vessel After the mixture was stirred at the same temperature for 1 hour the mixture was further stirred for 1 hour the mixture was stirred for 5 minutes to 1 hour (further, the mixture The resulting organic phase was directly subjected to purification by silica gel column chromatography (hexane/ethyl acetate or methylene chloride/methanol)