Trifluoroacetic acid → 1-benzyl-1'H-spiro[piperidine-4,5'-pyrano[3,2-c]pyrazol]-7'(6'H)-one

HRID 536287

Reaction equation

HRID 536287 reaction equation
[CH2:1]([N:8]1[CH2:31][CH2:30][C:11]2([O:19][C:18]3[C:14](=[N:15][N:16](CC4C=CC(OC)=CC=4)[CH:17]=3)[C:13](=[O:29])[CH2:12]2)[CH2:10][CH2:9]1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.FC(F)(F)C(O)=O>ClCCCl>[CH2:1]([N:8]1[CH2:31][CH2:30][C:11]2([O:19][C:18]3[CH:17]=[N:16][NH:15][C:14]=3[C:13](=[O:29])[CH2:12]2)[CH2:10][CH2:9]1)[C:2]1[CH:3]=[CH:4][CH:5]=[CH:6][CH:7]=1

Participants

4

Reactant 2

HCID 6422Trifluoroacetic acidHCID 66835469HCID 66835469, compound

Product 1

HCID 680654501-benzyl-1'H-spiro[piperidine-4,5'-pyrano[3,2-c]pyrazol]-7'(6'H)-oneYield 91.7%

Reagents, catalysts & solvents 1

HCID 111,2-DichloroethaneSolvent

Procedure

Dissolved 1-benzyl-2′-(4-methoxybenzyl)-2′H-spiro[piperidine-4,5′-pyrano[3,2-c]pyrazol]-7′(6′H)-one (428 mg, 1.02 mmol) in 20 mL 1,2-dichloroethane and treated with 10 mL trifluoroacetic acid. The resultant mixture was heated for 18 h at 90° C. The reaction was cooled to ambient temperature and concentrated to dryness under reduced pressure. The resultant residue was taken up in 50 mL saturated aqueous sodium bicarbonate and extracted with 2×50 mL ethyl acetate. The organic extracts were combined and dried over sodium sulfate, filtered and concentrated under reduced pressure. The resultant oil was flash chromatographed (25 g silica, stepgradient 5 column volumes 50% ethyl acetate/heptane, 10 CV 100% ethyl acetate) to yield 278 mg (91%) of 1-benzyl-1′H-spiro[piperidine-4,5′-pyrano[3,2-c]pyrazol]-7′(6′H)-one as a pale yellow solid. 1H NMR (400 MHz, CD3OD) δ ppm 7.27 (m, 6H), 3.55 (s, 2H), 2.64 (m, 4H), 2.45 (td, J=11.7, 2.5 Hz, 2H), 2.06 (d, J=12.1 Hz, 2H), 1.74 (m, 2H); m/z (M+1)=298.5.

Workup

  1. concentrationconcentrated to dryness under reduced pressure
  2. extractionextracted with 2×50 mL ethyl acetate
  3. dry with materialdried over sodium sulfate
  4. filtrationfiltered
  5. concentrationconcentrated under reduced pressure
  6. customchromatographed (25 g silica, stepgradient 5 column volumes 50% ethyl acetate/heptane, 10 CV 100% ethyl acetate)

Sources & evidence

ORD record
ord-f99288e8180e43f497c4a7b51e112e7c
Source dataset
uspto-grants-2014_10
Patent number
US08859577B2

Linked notes

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