Naphthalene → Naphtho(2,1-b)furan

HRID 2073380Notes

Reaction equation

[CH3:1][O:2][C:3]1[CH:12]=[C:11]2[C:6]([CH2:7][CH2:8][CH2:9][C:10]2=O)=[CH:5][CH:4]=1.[BH4-].[Na+].S([O-])(O)(=O)=O.[K+].Cl[C:23]1C(=O)C(C#N)=C(C#N)C(=O)C=1Cl.C1C2C(=CC=CC=2)C=CC=1.B(Br)(Br)Br.C1C=CC2C(=CC=CC=2O)C=1.C(O)(=O)CS>>[CH:23]1[C:12]2[C:11]3[C:6](=[CH:7][CH:8]=[CH:9][CH:10]=3)[CH:5]=[CH:4][C:3]=2[O:2][CH:1]=1

Participants

Reactant 8

HCID 931Naphthalene

HCID 1133Thioglycolic Acid

HCID 67752,3-Dichloro-5,6-dicyano-1,4-benzoquinone

HCID 70051-Naphthol

HCID 25134Boron tribromide

HCID 812767-Methoxy-1,2,3,4-tetrahydronaphthalen-1-one

HCID 516920Potassium bisulfate

HCID 4311764Sodium borohydride

Product 1

HCID 9192Naphtho(2,1-b)furan

Procedure

Alternatively, particularly for compounds of the formula II wherein R2 is a halogenoalkyl radical, 7-methoxy-1-tetralone (XVI) is acylated with an ester R2CO2Et to a β-diketone (XVII) which is reduced with sodium borohydride to the corresponding diol (XVIII). The diol is dehydrated with potassium hydrogen sulphate to the unsaturated alcohol (XIX) which is aromatised with 2,3-dichloro-5,6-dicyanobenzoquinone to the corresponding naphthalene derivative. Demethylation with boron tribromide to the naphthol (XX) followed by reaction with thioglycolic acid in the presence of base and thermal lactonisation gives the naphtho[2,1-b]furan derivative (XXI). The side chain hydroxy group is protected by reaction with tert-butyldimethylsilyl chloride to give a hydroxy-protected derivative which is alkylated to XXII with an iodoalkane, R4I, and the protecting silyl ether is removed with tetrabutylammonium fluoride to give the required compound of the formula II.

Sources & evidence

ORD record: ord-11f8007de87d471d9ebfe625c9982e64
Source dataset: uspto-grants-1990_04
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US04916148

Reaction notes

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