Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D311/00—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only hetero atom, condensed with other rings
  • C07D311/02—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only hetero atom, condensed with other rings ortho- or peri-condensed with carbocyclic rings or ring systems
  • C07D311/04—Benzo[b]pyrans, not hydrogenated in the carbocyclic ring
  • C07D311/58—Benzo[b]pyrans, not hydrogenated in the carbocyclic ring other than with oxygen or sulphur atoms in position 2 or 4
  • C07D311/70—Benzo[b]pyrans, not hydrogenated in the carbocyclic ring other than with oxygen or sulphur atoms in position 2 or 4 with two hydrocarbon radicals attached in position 2 and elements other than carbon and hydrogen in position 6
  • C07D311/72—3,4-Dihydro derivatives having in position 2 at least one methyl radical and in position 6 one oxygen atom, e.g. tocopherols

Definitions

• the present invention is directed to a process for the manufacture of a compound of formula (III),
• R 1 is Ci- 5 -alkyl
• R 2 is either H or Ci- 2 -alkyl
• R 4 is either H or Ci- 4 -alkoxy or Ci- 4 -alkyl
• R 3 and R 5 are independently from each other either H or Ci- 4 -alkyl, and the first of the two solvents is water,
• the second of the two solvents is selected from aliphatic Cs-s-hydrocarbons, cycloaliphatic Cs-s-hydrocarbons, dialkyl ethers and methyl-substituted benzenes and any mixture thereof.
• reaction can be also carried out with isoprene according to various publications with yields in the range of 53-62% (see R. H. Cichewicz, V. A. Kenyon, S. Whitman, N. M. Morales, J. F. Arguello, T. R. Holman, P. Crews:“Redox Inactivation of Human 15-Lipoxygenase by Marine-Derived Meroditerpenes and Synthetic Chromanes: Archetypes for a Unique Class of Selective and Recyclable Inhibitors”, J. Am. Chem. Soc. 2004, 126, 14910-14920; G. P. Kalena, A. Jain, A.
• Banerji «Amberlyst 15 Catalyzed Prenylation of Phenols: One-Step Synthesis of Benzopyrans.”, Molecules 1997, 2, 100-105 (using Amberlyst 15 in THF/heptane, 65-70° C, 2.5 h, 61%); V. K. Ahluwalia, K. K. Arora, R. S. Jolly:“Acid-catalysed condensation of isoprene with phenols. Formation of 2,2-dimethylchromans.”, J. Chem. Soc., Perkin Trans. 1 1982, 335-338 (H3PO4); F. Bigi, S. Carloni, R. Maggi, C. Muchetti, M.
• prenyl acetate has been shown to react with HQ catalyzed by ln(OTf) 3 , a salt of the rare earth metal indium, (see V. Vece, J. Ricci, S. Poulain- Martini, P. Nava, Y. Carissan, S. Humbel, E. Duhach:“ I n ( 111 ) - Cat a lysed Tandem C-C and C-0 Bond Formation between Phenols and Allylic Acetates”, Eur. J. Org. Chem. 2010, 6239-6248.).
• dichloromethane a halogenated solvent, had to be used.
• Step 1 MeSOsH as solvent; 50 mol-% of P 2 Os, yield 91% (see F. Camps, J. Coll, A. Messeguer, M. A. Pericas, S. Spainrt, W. S. Bowers, D. M. Soderlund:“An Improved Procedure for the Preparation of 2,2-Dimethyl-4-chromanones.”, Synthesis 1980, 725-727.).
• Step 2) LiAlH 4 , Et 2 0, yield 87% (see P. Anastasis, P. E. Brown:“Analogues of antijuvenile hormones.”, J. Chem. Soc., Perkin Trans. 1 1982, 2013-2018.).
• the total yield is 79% over the two steps.
• R 1 is Ci- 5 -alkyl
• R 2 is either H or Ci- 2 -alkyl
• R 4 is either H or Ci- 4 -alkoxy or Ci- 4 -alkyl
• R 3 and R 5 are independently from each other either H or Ci- 4 -alkyl
• the first of the two solvents is water
• both the used acid catalyst and excess of compound of formula (I) are reusable, simply by separating the product phase from the phase containing catalyst and excess of compound of formula (I).
• OR is preferably OH or acetate.
• R 1 is preferably methyl.
• R 2 is preferably H or methyl; more preferably R 2 is methyl.
• R 4 is preferably either H or methoxy or methyl, more preferably R 4 is H or methoxy.
• R 3 and R 5 are preferably independently from each other either H or methyl.
• alkyl and“alkoxy” in the context of the present invention encompass linear alkyl and branched alkyl, and linear alkoxy and branched alkoxy, respectively.
• Fig. 2-5 shows the synthesis of 2,2-dimethylchroman-6-ol (compound of formula (III- 1 )) starting from 1 ,4-hydroquinone (compound of formula (1-1 )) and 2-methylbut-3- en-2-ol (compound of formula (IIA-1 )).
• Fig. 3 shows the synthesis of 2,2-dimethylchroman-6-ol (compound of formula (MI- 1 )) starting from 1 ,4-hydroquinone (compound of formula (1-1 )) and isoprene
• FIG. 4 shows the synthesis of 2,2-dimethylchroman-6-ol (compound of formula (III- 1 )) starting from 1 ,4-hydroquinone (compound of formula (1-1 )) and a prenyl derivative (compound of formula (IIC-1 )).
• Fig. 5 shows the synthesis of 2,2-dimethylchroman-6-ol (compound of formula (III- 1 )) starting from 1 ,4-hydroquinone (compound of formula (1-1 )) and prenol
• the molar ratio of the compound of formula (I) to the compound of formula (IIA), (MB) or (IIC) is in the range of 6.0: 1 to 1.1 :1 , more preferably in the range of 4.0:1 to 1.3: 1 , even more preferably in the range of from 3.0: 1 to 1.5:1 , most preferably in the range of 2.5:1 to 1 .7:1 .
• all embodiments of the present invention with regard to the starting materials and the preferences as given above are realized.
• aliphatic Cs-s-hydrocarbons are hexane and heptane.
• hexane encompasses n-hexane, as well as any mixture of the isomers of hexane. The same applies for heptane.
• a preferred example of a cycloaliphatic Cs-s-hydrocarbon is cyclohexane.
• the alkyl groups in the dialkyl ethers may be identical or different, preferably they are different.
• the alkyl groups are aliphatic linear Ci- 5 -alkyl groups or branched C alkyl groups.
• a preferred example of a dialkyl ether is methyl tert- butyl ether.
• methyl-substituted benzenes are ortho-xylene, meta-xylene, para-xylene, mesitylene, pseudocumene, and toluene.
• the second solvent is hexane, cyclohexane, heptane, ortho-xylene, meta-xylene, para-xylene, mesitylene, pseudocumene, methyl tert- butyl ether, or toluene, and any mixture thereof.
• the second solvent is hexane, cyclohexane, heptane, ortho-xylene, meta-xylene, para-xylene, mesitylene, pseudocumene, methyl tert- butyl ether, or toluene.
• the first of the two solvents is water and the second of the two solvents is selected from either mesitylene, pseudocumene, ortho-xylene, meta-xylene, para-xylene or toluene, more preferably the first of the two solvents is water and the second of the two solvents is selected from either ortho-xylene, meta-xylene, para-xylene or toluene, most preferably the first of the two solvents is water and the second of the two solvents is toluene.
• the volume ratio of the first solvent to the second solvent during the reaction is in the range of 1 :4 to 4:1 , more preferably the volume ratio of the first solvent to the second solvent is in the range of 1 :3 to 3:1 , most preferably the volume ratio of the first solvent to the second solvent is in the range of 1 :2 to 2:1 .
• the total amount of the two solvents is in the range of 1 to 8 kg, preferably in the range of 2 to 6 kg, more preferably in the range of 2.5 to 5.5 kg, per kg of the compound of formula (I).
• all embodiments of the present invention with regard to the solvent and the preferences as given above are realized.
• the water may be added as such to the reaction mixture or as an aqueous solution of an acid catalyst with the preferences as disclosed below, i.e. a mixture of water and the acid catalyst may be used.
• the preferred amounts of water given above also encompass the water contained in the aqueous solution of the acid catalyst.
• Suitable acid catalysts are Bronsted acids and Lewis acids and any mixture thereof.
• Bronsted acids are sulfuric acid, phosphoric acid, acidic ion-exchange resins (e.g. Amberlyst 15), acidic clays (e.g. Montmorillonite K-10), zeolites (e.g. HSZ-360), hydrochloric acid, trifluoroacetic acid, trichloroacetic acid, acetic acid, formic acid, methanesulfonic acid, benzenesulfonic acid, para-toluenesulfonic acid, ethanesulfonic acid, trifluoromethanesulfonic acid, bis(perfluoroalkyl- sulfonyl)methanes (R’S0 2 )(R”S0 2 )CH 2 wherein R’ and R” each signify independently from each other a perfluoroalkyl group of the formula C n F 2n+i where n is an integer from 1 to 10, tris(perfluorosulfonyl)methane
• pentafluorophenyl group (-C 6 F 5 ) and R” and R’” each signify an identical perfluoroalkyl group of the above formula C n F 2n+i , methanetrisulfonic acid, and bis(trifluormethylsulfonyl)imide, and any mixture thereof, whereby the use of single catalysts is preferred.
• Lewis acids are Sc(OTf) 3 , Sc(NTf 2 ) 3 , ScCl 3 , Yb(OTf) 3 , YbCl 3 , Cu(OTf) 2 , FeCl 2 , Fe(OTf) 2 , ZnCl 2 , Zn(OTf) 2 , Zn(NTf 2 ) 3 , YCl 3 , Y(OTf) 3 , lnCl 3 , lnBr 3 , ln(OTf) 3 , ln(NTf 2 ) 3 , La(OTf) 3 , Ce(OTf) 3 , Sm(OTf) 3 , Gd(OTf) 3 , Bi(OTf) 3 in the absence or presence of 2,2-bipyridine and any mixture thereof, whereby the use of single catalysts is preferred.
• the acid catalyst is sulfuric acid, hydrochloric acid, formic acid, Amberlyst 15, trifluoroacetic acid, or phosphoric acid or their aqueous
• the acid catalyst is sulfuric acid, hydrochloric acid or Amberlyst 15, most preferably the acid catalyst is sulfuric acid. Mixtures of these catalysts may also be used.
• the acid catalyst is sulfuric acid and the concentration of said sulfuric acid is in the range of from 0.1 to 10 mol/L, preferably wherein the concentration of said sulfuric acid is in the range of 0.4 to 4.0 mol/L.
• the amount of the acid catalyst is in the range of 0.01 to 10 mol equivalents, more preferably in the range of 0.05 to 5 mol equivalents, most preferably in the range of 0.1 to 1 mol equivalents, relative to the amount of compound of formula (IIA), (MB), or (IIC).
• the reaction is preferably carried out at a temperature in the range of 50 to 140°C, more preferably in the range of 60 to 120°C, even more preferably in the range of 70 to 100°C, most preferably in the range of 75 to 90° C.
• the reaction is preferably carried out at a pressure in the range of 0.5 to 20 bar (absolute), more preferably at a pressure in the range of 0.7 to 10 bar (absolute), most preferably at a pressure in the range of 0.8 to 5 bar (absolute).
• Example 1 Synthesis of 2.2-dimethylchroman-6-ol starting from 1 .4- hydroquinone and 2-methylbut-3-en-2-ol
• the combined organic phases were washed with 100 ml. of brine (10 % aqueous NaCl solution), subsequently dried over sodium sulfate, filtered and evaporated at 40° C/200-10 mbar.
• the heterogeneous, crude material (31 .5 g) was digested in 50 ml. of heptane/ethyl acetate (90/10 w/w) and filtered.
• the filter cake (mostly HQ) was washed with 50 ml. of heptane/ethyl acetate (90/10 w/w).
• the filtrate was concentrated in vacuo (40°C/200-10 mbar), furnishing crude product (14.4 g).
• This material was purified by column chromatography; eluent gradient heptane to heptane/EtOAc 80:20 (w/w). The pure fractions were combined and concentrated in vacuo (40° C/200-10 mbar). The residue was taken up in 30 ml. of dichloromethane and subsequently evaporated again to dryness (40 ° C/200-0.1 mbar), furnishing 5.6 g of DMC as off-white crystals (31.4 mmol, 98.5% purity by qNMR, 37% yield).
• the toluene solution was then concentrated in a rotary evaporator to furnish 29.60 g of crude DMC as beige oil (assay 75.4% by ql_C, a chemical yield of 78.7% relative to MBE).
• the crude material was purified in a distillation apparatus equipped with a Vigreux column (20 cm) at 0.3 mbar and 125°C (internal temperature), furnishing one fraction: 22.40 g of DMC (assay 97.0% by quant. LC, 121.9 mmol, 76.5% isolated yield), mp. 74.5-75°C.
• Example 3 Synthesis of 2.2-dimethylchroman-6-ol starting from 1.4- hydroquinone and 2-methylbut-3-en-2-ol: Recycling of catalyst and 1 .4- hydroquinone phase
• a 1 .5 L 4-necked sulfonation flask equipped with argon inlet, magnetic stirrer, oil bath and thermometer was charged with 651 g aqueous phase from the previous run (carried out on the same scale as the present run; containing hydroquinone, approx. 3 mol equiv., -1 .17 mol, and sulfuric acid, -0.4 M, 0.78 mol, 0.5 mol equiv.
• Example 6 Synthesis of 2.2-dimethylchroman-6-ol starting from 1 .4- hydroquinone and 2-methylbut-3-en-2-ol in the presence of Amberlyst 15 as acid catalyst A 200 ml. 4-necked sulfonation flask equipped with argon inlet, magnetic stirrer, oil bath and thermometer was charged with 8.0 g of 1 ,4-hydroquinone (72.2 mmol, 99.5%, 1 .9 mol equiv.) and 2-methyl-3-buten-2-ol (4.0 ml_, 39 mmol, 1 .0 mol equiv.), which were then suspended in 50 ml.
• Example 14 Synthesis of 2.2-dimethylchroman-6-ol (“DM- chromanol”) starting from 1 .4-hydroquinone (“HQ”) and 2-methylbut-3-en-2-ol (“MBE”) according to the conditions disclosed in US 4,217,285 , i.e. in the presence of ZnCb, silica-alumina and concentrated hydrochloric acid
• DM- chromanol 2.2-dimethylchroman-6-ol
• HQ 1 .4-hydroquinone
• MBE 2-methylbut-3-en-2-ol

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• 2019
  • 2019-03-29 EP EP19713808.4A patent/EP3774756A1/de not_active Withdrawn
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