Toluene → tert-butyl 2-(4-chloro-6,7-dihydro-5H-cyclopenta[b]pyridin-2-yl)-1H-pyrrole-1-carboxylate

HRID 1508793Notes

Reaction equation

HRID 1508793 reaction equation
Cl[C:2]1[N:7]=[C:6]2[CH2:8][CH2:9][CH2:10][C:5]2=[C:4]([Cl:11])[CH:3]=1.[C:12]([N:19]1[CH:23]=[CH:22][CH:21]=[C:20]1B(O)O)([O:14][C:15]([CH3:18])([CH3:17])[CH3:16])=[O:13].C([O-])([O-])=O.[Cs+].[Cs+].C1(C)C=CC=CC=1>O.C(OCC)(=O)C.C1C=CC([P]([Pd]([P](C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)([P](C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)[P](C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)=CC=1.CCO>[Cl:11][C:4]1[CH:3]=[C:2]([C:20]2[N:19]([C:12]([O:14][C:15]([CH3:18])([CH3:17])[CH3:16])=[O:13])[CH:23]=[CH:22][CH:21]=2)[N:7]=[C:6]2[CH2:8][CH2:9][CH2:10][C:5]=12

Participants

9

Reactant 4

HCID 1140TolueneHCID 10796Cesium carbonateHCID 27343211-(tert-Butoxycarbonyl)-2-pyrroleboronic AcidHCID 122148172,4-Dichloro-6,7-dihydro-5H-cyclopenta[b]pyridine

Product 1

HCID 118037056tert-butyl 2-(4-chloro-6,7-dihydro-5H-cyclopenta[b]pyridin-2-yl)-1H-pyrrole-1-carboxylateYield 32.5%

Reagents, catalysts & solvents 4

HCID 178418397HCID 178418397, compoundCatalystHCID 702EthanolSolventHCID 962WaterSolvent2×HCID 8857Ethyl AcetateSolvent

Conditions

Temperature
90 °C

Procedure

A 20-mL sealed tube was charged with 2,4-dichloro-6,7-dihydro-5H-cyclopenta[b]pyridine (0.250 g, 1.33 mmol), 1-Boc-pyrrole-2-boronic acid (0.308 g, 1.46 mmol), tetrakis(triphenylphosphine)palladium(0) (0.076 g, 0.066 mmol), and Cs2CO3 (1.30 g, 3.99 mmol). Toluene (8 ml), EtOH (2 ml) and water (4 ml) were added. The resulting mixture was stirred under Ar at 90° C. for 23 h. After cooling to room temperature, the reaction solution was diluted with water (5 mL) and ethyl acetate (60 mL). The aqueous layer was separated and the organic layer was washed with saturated sodium chloride (5 mL) then dried over sodium sulfate, filtered, and concentrated under reduced pressure. The residue was purified by chromatography on silica using hexane/ethyl acetate (100:0 to 75:250) as eluent to afford tert-butyl 2-(4-chloro-6,7-dihydro-5H-cyclopenta[b]pyridin-2-yl)-1H-pyrrole-1-carboxylate (0.138 g, 32%) as a yellow oil. MW=318.80. 1H NMR (CDCl3, 500 MHz) δ 7.33 (dd, J=3.5, 2.0 Hz, 1H), 7.17 (s, 1H), 6.37 (dd, J=3.0, 2.0 Hz, 1H), 6.21 (t, J=3.5 Hz, 1H), 3.09 (t, J=7.5 Hz, 2H), 3.04 (t, J=7.5 Hz, 2H), 2.17 (quin, J=7.5 Hz, 2H), 1.38 (s, 9H). MS: ESI+, m/z 319 [M+H]+ and 4-chloro-2-(1H-pyrrol-2-yl)-6,7-dihydro-5H-cyclopenta[b]pyridine (0.077 g, 26%) as an off-white solid. MW=218.68. 1H NMR (CDCl3, 500 MHz) δ 9.63 (br s, 1H), 7.30 (s, 1H), 6.87-6.85 (m, 1H), 6.65-6.62 (m, 1H), 6.29-6.25 (m, 1H), 3.01 (t, J=7.5 Hz, 2H), 2.96 (t, J=7.5 Hz, 2H), 2.13 (quin, J=7.5 Hz, 2H); ESI MS m/z 218 [M]+.

Workup

  1. customA 20-mL sealed tube
  2. temperatureAfter cooling to room temperature
  3. customThe aqueous layer was separated
  4. washthe organic layer was washed with saturated sodium chloride (5 mL)
  5. dry with materialthen dried over sodium sulfate
  6. filtrationfiltered
  7. concentrationconcentrated under reduced pressure
  8. customThe residue was purified by chromatography on silica

Sources & evidence

ORD record
ord-9e64f34c78de464b88fc7941eb6305c5
Source dataset
uspto-grants-2015_12
Patent number
US09221843B2

Reaction notes

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