Chromocarb → 3,4-dihydro-2H-1-benzopyran-2-carboxylic acid

HRID 575827Notes

Reaction equation

HRID 575827 reaction equation
O=[C:2]1[C:11]2[C:6](=[CH:7][CH:8]=[CH:9][CH:10]=2)[O:5][C:4]([C:12]([OH:14])=[O:13])=[CH:3]1>CC(O)=O.[Pd]>[O:5]1[C:6]2[C:11](=[CH:10][CH:9]=[CH:8][CH:7]=2)[CH2:2][CH2:3][CH:4]1[C:12]([OH:14])=[O:13]

Participants

4

Reactant 1

HCID 2741Chromocarb

Product 1

HCID 27236653,4-dihydro-2H-1-benzopyran-2-carboxylic acidYield 72.2%

Reagents, catalysts & solvents 2

HCID 23938PalladiumCatalystHCID 176Acetic AcidSolvent

Procedure

A mixture of 4-oxochromene-2-carboxylic acid (20.0 g, 105 mmol) and Pd/C (3.0 g, w/w=10%) in AcOH (200 mL) was placed in Parr hydrogenation apparatus under H2 (50 psi) and stirred for 25 h at rt. It was then filtered and concentrated. The residue was suspended in water (300 mL), stirred for 10 min, filtered and dried to give 3,4-dihydro-2H-chromene-2-carboxylic acid (13.5 g, 72%) as a white solid. BH3 (57 mL, 114 mmol, 2.0 M in THF) was added slowly to a solution of this carboxylic acid in THF (120 mL) at 0° C. The reaction mixture was then warmed to rt and stirred for 5 h at this temperature. THF/H2O (30 mL, 1:1) was added drop wise while keeping the temperature between 0-5° C. and stirred for 20 min. K2CO3 (26.0 g, 189 mmol) was added and the reaction was vigorously stirred for 30 min. The THF layer was separated and concentrated to give the title compound (11.0 g, 89%) as a brown oil. 1H NMR (400 MHz, CDCl3): δ 7.10-7.03 (m, 2H), 6.86-6.81 (m, 2H), 4.14-4.08 (m, 1H), 3.85-3.68 (m, 2H), 2.92-2.84 (m, 1H), 2.80-2.73 (m, 1H), 1.98-1.92 (m, 1H), 1.90-1.79 (m, 1H). LCMS: 165 (M+1)+

Workup

  1. filtrationIt was then filtered
  2. concentrationconcentrated
  3. stirringstirred for 10 min
  4. filtrationfiltered
  5. customdried

Sources & evidence

ORD record
ord-0b8d74c35b7d4c1fbc543440fd3f37cf
Source dataset
uspto-grants-2015_05
Patent number
US09034900B2

Reaction notes

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