Hydrochloric Acid → 2,5-Dimethylnaphtho[1,2-d]tellurazole

HRID 543079Notes

Reaction equation

HRID 543079 reaction equation
Cl[TeH:2]1[C:6]2[CH:7]=[C:8]([CH3:15])[C:9]3[C:14]([C:5]=2[NH:4]O1)=[CH:13][CH:12]=[CH:11][CH:10]=3.[BH4-].[Na+].[C:18](OC(=O)C)(=O)[CH3:19].Cl>O1CCCC1.CO>[CH3:18][C:19]1[Te:2][C:6]2[CH:7]=[C:8]([CH3:15])[C:9]3[C:14](=[CH:13][CH:12]=[CH:11][CH:10]=3)[C:5]=2[N:4]=1

Participants

7

Reactant 4

HCID 313Hydrochloric AcidHCID 7918Acetic AnhydrideHCID 4311764Sodium borohydrideHCID 178421806HCID 178421806, compound

Product 1

HCID 143241222,5-Dimethylnaphtho[1,2-d]tellurazoleYield 32.8%

Reagents, catalysts & solvents 2

HCID 887MethanolSolventHCID 8028TetrahydrofuranSolvent

Conditions

Temperature
5 °C

Procedure

3-Chloro-5-methylnaphth[2,1-c][1,2,5]oxatellurazole (Example 4) (16.7 g=0.05 mole) was suspended in a mixture of tetrahydrofuran (THF, 200 ml) and methanol (40 ml) in a 500 ml three necked flask fitted with a nitrogen inlet, a condenser, and a powder addition funnel. Sodium borohydride was added under a nitrogen atmosphere and in small portions until the reaction mixture was a pale orange yellow. This required about 5 to 6 g. The powder addition funnel was then removed and replaced with a stopper. The reaction mixture was then cooled to 5° C. and acetic anhydride (5.1 g=0.05 mole) added slowly through the condenser. The reaction mixture transiently turned a bright orange. Concentrated hydrochloric acid (25 ml) was then added in one portion, the ice bath removed, and the mixture stirred to room temperature. As the reaction mixture warmed up, a crystalline deposit appeared and was collected by filtration. The crystalline deposit was washed with tetrahydrofuran until the filtrate was colorless and clear. The filtrate was then heated to boiling with a mixture of isopropanol (175 ml) and concentrated ammonium hydroxide (25 ml) and filtered hot with Celite®, the cooled filtrate was diluted with water until crystallization started. A first crop of pale yellow needles (5.06 g), m.p. 110°-112° C. was obtained. A further 1.65 g of product were obtained by two further extractions with the same solvent mixture, giving a total yield of 6.71 g=43.3% of theory. For analysis, the material was recrystallized from isopropanol. This did not change the melting point. Elemental analyses were in agreement with that expected for the structural formula.

Workup

  1. customfitted with a nitrogen inlet, a condenser, and a powder addition funnel
  2. additionThe powder addition funnel
  3. customwas then removed
  4. customthe ice bath removed
  5. temperatureAs the reaction mixture warmed up
  6. filtrationwas collected by filtration
  7. washThe crystalline deposit was washed with tetrahydrofuran until the filtrate
  8. temperatureThe filtrate was then heated
  9. additionto boiling with a mixture of isopropanol (175 ml) and concentrated ammonium hydroxide (25 ml)
  10. filtrationfiltered hot with Celite®
  11. additionthe cooled filtrate was diluted with water until crystallization

Sources & evidence

ORD record
ord-eebd9828c14244db87d31f6a1e86d196
Source dataset
uspto-grants-1987_04
Patent number
US04661438

Reaction notes

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