Acetic Acid → HCID 20332236, compound

HRID 2057404Notes

Reaction equation

HRID 2057404 reaction equation
[C:1]1([C:7]2[CH:8]=[C:9]([Cl:24])[C:10]3[O:15][CH2:14][CH2:13]C(C#N)(O[Si](C)(C)C)[C:11]=3[CH:23]=2)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.Cl.[C:26]([OH:29])(=[O:28])[CH3:27]>>[C:1]1([C:7]2[CH:8]=[C:9]([Cl:24])[C:10]3[O:15][CH2:14][CH2:13][CH:27]([C:26]([OH:29])=[O:28])[C:11]=3[CH:23]=2)[CH:2]=[CH:3][CH:4]=[CH:5][CH:6]=1

Participants

4

Reactant 3

HCID 176Acetic AcidHCID 313Hydrochloric AcidHCID 20332238HCID 20332238, compound

Product 1

HCID 20332236HCID 20332236, compound

Procedure

To a 500 ml. single neck reaction flask equipped with a magnetic stirrer, reflux condenser, and nitrogen inlet was added 6-phenyl-8-chloro-4-cyano-4-trimethylsilyloxy-3,4-dihydro-2H-1-benzopyran (3.0 g.). In one portion was added stannous chloride dihydrate (15 g.) followed by glacial acetic acid (20 ml.) and concentrated hydrochloric acid (20 ml.). The reaction flask was immediately flushed with nitrogen and plunged into a preheated (140° C.) oil bath. With vigorous stirring the reaction mixture was heated at reflux for 65 hrs., cooled to room temperature, diluted with 500 ml. chloroform, the layers separated, and the aqueous layers again saturated with chloroform. The combined organic layers were extracted with three 150 ml. portions of 2 N aqueous potassium hydroxide, and the combined basic aqueous layers back-extracted with one 150 ml. portion of ether. Acidification of the basic aqueous layer with ice bath cooling, extraction with three 250 ml. portions of chloroform, drying of the combined organic layers over magnesium sulfate, filtration, and removal of the volatiles afforded 6-phenyl-8-chloro-3,4-dihydro-2H-1-benzopyran-4-carboxylic acid. Filtration of a chloroform solution of the acid through 400 ml. of silica gel (EM Reagents, 70-230 mesh) with elution by three liters of chloroform removes a small amount of an -hydroxy acid impurity. Recrystallization from cyclohexane yielded 0.93 g. (38%) of the acid, m.p. 187°-188° C.

Workup

  1. customsingle neck reaction flask equipped with a magnetic stirrer
  2. temperaturereflux condenser, and nitrogen inlet
  3. customThe reaction flask was immediately flushed with nitrogen
  4. customplunged into a preheated (140° C.) oil bath
  5. temperaturewas heated
  6. temperatureat reflux for 65 hrs
  7. additiondiluted with 500 ml
  8. customchloroform, the layers separated
  9. extractionThe combined organic layers were extracted with three 150 ml
  10. extractionportions of 2 N aqueous potassium hydroxide, and the combined basic aqueous layers back-extracted with one 150 ml
  11. temperatureAcidification of the basic aqueous layer with ice bath cooling
  12. extractionextraction with three 250 ml
  13. dry with materialportions of chloroform, drying of the combined organic layers over magnesium sulfate, filtration, and removal of the volatiles

Sources & evidence

ORD record
ord-c522bc89cca143c4a7567a50485974b6
Source dataset
uspto-grants-1980_07
Patent number
US04210663

Reaction notes

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