Formic Acid → 3-Formamido-2-phenyl-benzo(b)thiophene

HRID 236784Notes

Reaction equation

HRID 236784 reaction equation
[CH3:1][N:2]([C:6]1[C:7]2[CH:20]=[CH:19][CH:18]=[CH:17][C:8]=2[S:9][C:10]=1[C:11]1[CH:16]=[CH:15][CH:14]=[CH:13][CH:12]=1)CCC.C(O)=[O:22]>O>[CH:1]([NH:2][C:6]1[C:7]2[CH:20]=[CH:19][CH:18]=[CH:17][C:8]=2[S:9][C:10]=1[C:11]1[CH:16]=[CH:15][CH:14]=[CH:13][CH:12]=1)=[O:22]

Participants

4

Reactant 2

HCID 284Formic AcidHCID 15700634HCID 15700634, compound

Product 1

HCID 157006253-Formamido-2-phenyl-benzo(b)thiophene

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Procedure

Preparation of the starting product by reduction of the 3-formamido-2-phenyl-benzo(b)thiophene which can be isolated either by drying of the intermediate product formed from preparation of the 3-amino-2-phenyl-benzo(b)thiophene from the 2-phenyl-benzo(b)thiophen-3-ol produced as an intermediate product (described following Example 14) by heating for 1 hour the 3-amino-2-phenyl-benzo(b)thiophene with the same quantity of formic acid at 98 to 100%, followed by dissolving in water and drying. In both cases, 3-formamido-2-phenyl-benzo(b)thiophene is obtained in a quantitative yield: thin colourless needles, mp 185°-186° C. (benzene). 3.0 g (11.8 mmol) of this amide and 1.08 g (28.4 mmol) of LiAlH4 in 60 milliliters of absolute dioxan are refluxed with stirring for 30 minutes. Water is added to the cooled reaction mixture to decompose the excess LiAlH4 and, after the addition of approximately 100 milliliters of CH2Cl2, it is stirred for a further 15 minutes. After centrifuging with the addition of a filtration aid the organic phase is dried over K2CO3 and evaporated. The hydrochloride of the solution of the residue is precipitated in a little chloroform by the action of hydrochloric gas: 2.6 g (80% of theory). The hydrochloride of 3-methylamino-2-phenyl(b)thiophene, colourless crystals in ethanol-ether, decomposition from 198° C. (in sealed tube). From this salt the base is released by the action of ammonia: 3-methylamino- 2-phenyl -benzo(b)thiophene, yellow rods, mp 78°-79° C. (methanol).

Workup

  1. customproduced as an intermediate product (described following Example 14)
  2. customdrying

Sources & evidence

ORD record
ord-9aa9b1e9441041988ede3b3106123a81
Source dataset
uspto-grants-1979_06
Patent number
US04157399

Reaction notes

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