Water → 2-Phenyl-3,4-dihydro-2H-1-benzopyran

HRID 1462958Notes

Reaction equation

HRID 1462958 reaction equation
O[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][C:3]=1[CH2:8][CH2:9][CH:10]([C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=1)[OH:11].O>S(=O)(=O)(O)O>[O:11]1[C:4]2[C:3](=[CH:2][CH:7]=[CH:6][CH:5]=2)[CH2:8][CH2:9][CH:10]1[C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=1

Participants

4

Reactant 2

HCID 962WaterHCID 610801HCID 610801, compound

Product 1

HCID 941562-Phenyl-3,4-dihydro-2H-1-benzopyranYield 21.7%

Reagents, catalysts & solvents 1

HCID 1118Sulfuric AcidSolvent

Procedure

2-Hydroxychalcone (28.5 g) was stirred with ethanol (500 ml) whilst sodium borohydride (9.45 g) was added in small portions. The solution, which turned from red to pale yellow was allowed to stand overnight at room temperature, then the solvent was evaporated off and the residue extracted with dichloromethane, washing with water. Evaporation of the solvent yielded 3-(o-hydroxyphenyl)-1-phenylpropan-1-ol (24.4 g). 1.0 g of this carbinol was dissolved in concentrated sulphuric acid, and the solution was allowed to stand at room temperature for 2 hr. The solution was poured into iced water, and the sticky orange product filtered off, washed with water, dried, and chromatographed on alumina, eluting with toluene. Evaporation of the eluate gave flavan (0.20 g), which was recrystallised from petroleum ether, b.p. 40°-60°, to give flavan m.p. 42°-43°.

Workup

  1. filtrationthe sticky orange product filtered off
  2. washwashed with water
  3. customdried
  4. customchromatographed on alumina
  5. washeluting with toluene
  6. customEvaporation of the

Sources & evidence

ORD record
ord-79e42618b81b4ebfb4abe00cbf1b77ef
Source dataset
uspto-grants-1984_07
Patent number
US04461907

Reaction notes

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