5,7-Difluoro-3,4-dihydronaphthalen-1(2H)-one → HCID 18673262, compound

HRID 1058169Notes

Reaction equation

HRID 1058169 reaction equation
[F:1][C:2]1[CH:11]=[C:10]([F:12])[CH:9]=[C:8]2[C:3]=1[CH2:4][CH2:5][CH2:6][C:7]2=O.[CH2:14]([Mg]Br)[CH:15]=[CH2:16]>O1CCCC1.CCOCC>[F:1][C:2]1[CH:11]=[C:10]([F:12])[CH:9]=[C:8]2[C:3]=1[CH2:4][CH2:5][CH:6]=[C:7]2[CH2:16][CH:15]=[CH2:14]

Participants

5

Reactant 2

HCID 143687015,7-Difluoro-3,4-dihydronaphthalen-1(2H)-oneHCID 178455850HCID 178455850, compound

Product 1

HCID 18673262HCID 18673262, compound

Reagents, catalysts & solvents 2

HCID 3283Diethyl EtherSolventHCID 8028TetrahydrofuranSolvent

Procedure

A solution of 5, 7-difluoro-1-tetralone [110931-79-8] (prepared in accordance with DE-A 3702039) in tetrahydrofuran is added to an equimolar amount of an allylmagnesium bromide solution in ether at 0° C. The reaction mixture is subjected to conventional aqueous acidic workup (Mohammadi et al., J. Lab. Cpd. Radiopharm. XXIV, 317 (1987)) and distillation. The 5,7-difluoro-1-(1-propen-3-yl)-3,4-dihydronaphthalene obtained is reacted with an equimolar amount of thexyl-borane in terahydrofuran to give B-thexyl6,8-difluoro-2,3,4,4a,9,9a,10-octahydro-1-boraphenanthrene which is reacted with equimolar amounts of sodium cyanide at room temperature without further characterization. After 2 h, an equimolar amount of trifluoroacetic anhydride (TFAA) is added dropwise at −75° C., and the mixture is brought to room temperature with stirring. 3 equivalents of NaOH are added and the mixture is oxidized with 50% H2O2, finally at 50° C.; extraction and chromatography yield 1-keto6,8-difluoro-1,2,3,4,4a,9,9a,10-octahydrophenanthrene. As described by Mohammadi et al., J. Lab. Cpd. Radiopharm. XXIV, 317 (1987), this product can be converted into 1-keto-6,8-difluoro-2-propyl-1,2,3,4,4a,9,9a,10-octahydrophenanthrene by reacting with lithium diisopropylamide (LDA) followed by addition of n-propyl bromide. This product can be converted into 6,8-difluoro-1,2,3,4,4a,9,9a,10-octahydrophenanthrene by reducing with triethylsilane in trifluoroacetic acid. 6,8-Di-fluoro-7-pentyl-2-propyl-1,2,3,4,4a,9,9a,10-octahydrophenanthrene is obtained by ortho metalation using “Schlosser base” (i.e. butyllithium and potassium tert-butylate; see, for example: F. Mongin, M. Schlosser, Tetrahedron Lett. 1996, 37, 6551-6554) at −75° C., quenching with n-pentyl bromide and conventional workup by hydrolysis, extraction, chromatography (silica gel, dichloromethane) and repeated recrystallization (to increase the proportion of the desired isomer, among other things).

Workup

  1. distillationThe reaction mixture is subjected to conventional aqueous acidic workup (Mohammadi et al., J. Lab. Cpd. Radiopharm. XXIV, 317 (1987)) and distillation

Sources & evidence

ORD record
ord-86bf01d5eabc481d88bdc07feb16c261
Source dataset
uspto-grants-2003_02
Patent number
US06515163B2

Reaction notes

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