p-Toluenesulfonic acid → 8,8,10-trimethyl-2H,8H-benzo[1,2-b;5,4-b']dipyran-2-one

HRID 1587053

Reaction equation

HRID 1587053 reaction equation
[CH3:1][C:2]1[C:3]([OH:13])=[CH:4][CH:5]=[C:6]2[C:11]=1[O:10][C:9](=[O:12])[CH:8]=[CH:7]2.[CH3:14][C:15](O)([C:17]#[CH:18])[CH3:16].C1(C)C(C)=CC=CC=1.C1(C)C=CC(S(O)(=O)=O)=CC=1>>[CH3:14][C:15]1([CH3:16])[O:13][C:3]2=[C:2]([CH3:1])[C:11]3[O:10][C:9](=[O:12])[CH:8]=[CH:7][C:6]=3[CH:5]=[C:4]2[CH:18]=[CH:17]1

Participants

5

Reactant 4

HCID 6101p-Toluenesulfonic acidHCID 7237O-XyleneHCID 82582-Methyl-3-butyn-2-olHCID 53809787-Hydroxy-8-methyl coumarin

Product 1

HCID 131095828,8,10-trimethyl-2H,8H-benzo[1,2-b;5,4-b']dipyran-2-oneYield 33%

Procedure

A solution prepared from 5.0 mmol of 8-methyl-7-hydroxycoumarin and 6.0 mmol of 2-methyl-3-butyn-2-ol in 40 ml of xylene containing 0.095 g (0.50 mmol) of p-toluenesulfonic acid was refluxed with magnetic stirring for 4 hours. The solvent was distilled off in vacuo and the oily contents of the flask chilled in an ice-salt water bath to induce crystallization. The white microneedles, 33% yield, were recrystallized from methanol to analytical purity, m.p. 105°-107° C. (lit. m.p. 106°-107° C.). The 1H-NMR spectrum was also identical to that reported, see P. Rodighiero et al., reference cited above.

Workup

  1. temperaturewas refluxed
  2. distillationThe solvent was distilled off in vacuo
  3. temperaturethe oily contents of the flask chilled in an ice-salt water bath
  4. customcrystallization
  5. customThe white microneedles, 33% yield, were recrystallized from methanol to analytical purity, m.p. 105°-107° C. (lit. m.p. 106°-107° C.)

Sources & evidence

ORD record
ord-cfc078f11e9c459db970a3fad57e8112
Source dataset
uspto-grants-1993_06
Patent number
US05216176

Linked notes

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