Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
  • C07D307/77—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom ortho- or peri-condensed with carbocyclic rings or ring systems
  • C07D307/78—Benzo [b] furans; Hydrogenated benzo [b] furans
  • C07D307/79—Benzo [b] furans; Hydrogenated benzo [b] furans with only hydrogen atoms, hydrocarbon or substituted hydrocarbon radicals, directly attached to carbon atoms of the hetero ring

Definitions

• the present invention relates to process for preparing 2,3-dihydro-2- methyl-2-alkylbenzofuran derivatives of the formula(I) useful as intermediate of agricultural chemicals and pharmaceutical products.
• X is selected from the group consisting of hydrogen, halogen, hydroxy group, aldehyde group and C, ⁇ C 6 alkyl group ; and R is selected from the group consisting of C ] ⁇ C 6 alkyl group.
• 2,3-Dihydro-2-methyl-2-alkylbenzofuran derivatives of the formula(I) were already known as intermediates of agricultural chemicals such as insecticides and pharmaceutical products.
• 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran known as carbofuranphenol
• carbofuranphenol was very useful intermediate of 2,3-dihydro-2,2-dimethyl- 7-hydroxybenzofuranyl methylcarbamate as an insecticide.
• 2,3-dihydro-2,2-dimethylbenzofuranaldehyde derivatives were known as intermediate of pyrethroide derivatives which were known in the art as an insecticide[Japanese Patent No. 402,753 Al; European Patent unexamined publication No. 0473,041(1992) ; German Patent No.2108,932;
• the present invention is accomplished the new and easy process to prepare 2,3-dihydro-2-methyl-2-alkylbenzofuran derivatives, which is
• the object of the present invention is to provide a new process for preparing 2,3-dihydro-2-methyl-2-alkylbenzofuran derivatives, which may be used for the intermediates of agricultural chemicals and pharmaceutical products such as 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuranyl methylcarbamate or pyrethroide as an insecticide.
• the present invention is a process for preparing the compounds of the formula(I), which is characterized by the Claisen rearrangement of ( ⁇ -alkylallyl)oxybenzene derivatives of the formula(II) to give stereoisomers of the formula (III-l) and (III-2), and then cyclization of formula(III-l) and (III-2) in the presence of a catalytic amount of iodine and an inert organic solvent at room temperature,
• Claisen rearrangement of ( ⁇ -alkylallyl)oxybenzene derivatives of the formula(II) may be carried out in high boiling solvent or in the absence of solvent at a temperature ranged from 180 TJ to 250 t, preferably at a temperature ranged from 210 "C to 220
• solvents are N,N-dimethylaniline, or dodecane etc..
• reaction products prepared by Claisen rearrangement which are 2-( ⁇ -alkylallyl)phenol derivatives having the formula(III-l ) and 2-(alkylpropenyl)phenol derivatives having the formula(III-2) can occur in any of the possible stereoisomeric configuration.
• the stereoisomers may be used as the mixtures of stereoisomers or may be used respectively as essentially pure stereoisomer to afford the compound of the formula(I).
• the amount of iodine as catalyst is preferably 0.1 ⁇ 1 equimolar quantity, more preferably 0.2 equimolar quantity to the compound of the formula(III-l) and /or (III-2).
• the preferred solvents are hydrocarbon such as dichloromethane, chloroform, carbon tetrachloride,
• the main feature of process according to the present invention is not caused iodocyclization by reacting iodine with 2-methallyl phenol or 2- iosobutenyl phenolfTetrahedron, Vol. 46, pp. 3321 ⁇ 3408(1990)]. And the compounds of the formula(I) are obtained quantitatively in mild condition.
• N,N-dimethylformamide(30 ml) were added anhydrous potassium carbonate(14 g, 0.1 mol) and methallyl chloride(20 ml, 0.2 mol) with stirring.
• the reaction mixture was heated at reflux for 18 hours.
• the reaction mixture was cooled to room temperature and filtered, and the filtrate was concentrated.
• the residue was dissolved in 2N hydrochloric acid(100 ml), and extracted sequentially with hexane(50 ml x 3 ) and ethyl acetate(50 ml x 3).
• the organic layer was washed with 20% aqueous sodium hydroxide (50 ml x
• the reaction mixture was heated at reflux for 18 hours.
• the reaction mixture was cooled to room temperature and filtered, the filtrate was concentrated.
• the reaction mixture was diluted with hexane(50 ml), extracted with Claisen alkali(25 ml x 3), and washed with hexane.
• the alkali layer was cooled to 0 "C, neutralized with cone, hydrochloric acid, and extracted with diethyl ether.
• the resulting organic layer was dried over anhydrous magnesium sulfate, filtered, and then concentrated under reduced

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Furan Compounds (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 1996
  • 1996-06-12 CN CN96180326.6A patent/CN1224423A/zh active Pending
  • 1996-06-12 WO PCT/KR1996/000090 patent/WO1997047615A1/en not_active Application Discontinuation
  • 1996-06-12 JP JP10501468A patent/JP2000507600A/ja active Pending
  • 1996-06-12 CA CA002258131A patent/CA2258131A1/en not_active Abandoned
  • 1996-06-12 EP EP96918908A patent/EP0912538A1/en not_active Withdrawn

Non-Patent Citations (1)

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