Phosphorus pentachloride → Naphtho(2,3-b)thiophene-4,9-dione

HRID 628206Notes

Reaction equation

HRID 628206 reaction equation
[S:1]1[CH:5]=[CH:4][CH:3]=[C:2]1[C:6]([C:8]1[CH:16]=[CH:15][CH:14]=[CH:13][C:9]=1[C:10]([OH:12])=O)=[O:7].P(Cl)(Cl)(Cl)(Cl)Cl.[Cl-].[Al+3].[Cl-].[Cl-]>[N+](C1C=CC=CC=1)([O-])=O>[S:1]1[CH:5]=[CH:4][C:3]2[C:10](=[O:12])[C:9]3[C:8]([C:6](=[O:7])[C:2]1=2)=[CH:16][CH:15]=[CH:14][CH:13]=3

Participants

5

Reactant 3

HCID 24819Phosphorus pentachlorideHCID 2826542-(2-Thienylcarbonyl)benzoic acidHCID 6451240Aluminum(III) Chloride

Product 1

HCID 98578Naphtho(2,3-b)thiophene-4,9-dioneYield 50%

Reagents, catalysts & solvents 1

HCID 7416NitrobenzeneSolvent

Procedure

2-(thiophene-2-carbonyl)benzoic acid (1, 14.0 g, 60.3 mmol, 1.0 equiv.), nitrobenzene (400 mL), and phosphorus pentachloride (18.8 g, 90.4 mmol. 1.5 equiv.) were added to a schlenk flask. Aluminum chloride was then added (12.1 g, 90.4 mmol, 1.5 equiv.), and the reaction was stirred for 1 hour at room temperature followed by 4 hours at 140° C. The solvent was distilled off under vacuum, and the black residue was sonicated in dichloromethane (500 mL) and filtered through CELITE®. The filtrate was concentrated in vacuo and purified by column chromatography (silica gel, dichloromethane:hexanes (1:1)→dichloromethane). The product was further purified by recrystallization from methanol to give 2 as brown needle-shaped crystals (6.45 g, 50%). 1H NMR (500 MHz, CDCl3) δ8.26-8.24 (m, 2H), 7.78-7.77 (m, 2H), 7.75-7.71 (m, 2H). m.p. 232-234° C.

Workup

  1. waitfollowed by 4 hours at 140° C
  2. distillationThe solvent was distilled off under vacuum
  3. customthe black residue was sonicated in dichloromethane (500 mL)
  4. filtrationfiltered through CELITE®
  5. concentrationThe filtrate was concentrated in vacuo
  6. custompurified by column chromatography (silica gel, dichloromethane:hexanes (1:1)→dichloromethane)
  7. customThe product was further purified by recrystallization from methanol

Sources & evidence

ORD record
ord-29696e7d152a493ca59c18ca89ed50a9
Source dataset
uspto-grants-2016_04
Patent number
US09312501B2

Reaction notes

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