Reductive-alkylation and aromatic coupling reactions of 1,4-benzoquinone derivatives promoted by ethylaluminum dichloride.
Ferreira, Vitor F.; Schmitz, Francis J.
J. Organomet. Chem. (1998), 571(1), 1-6.
4-Ethoxyphenol
Obtained in 77% yield from 1,4-benzoquinone (120 mg, 1.10 mmol); m.p. 65-66 (lit. 65-67°C);
General procedure
To a solution of the appropriate benzoquinone derivative (1 mmol) in 5 ml of dry dichloromethane, 2 ml (two equivalents) of a solution of 1 M EtAlCl2 in hexane was added dropwise under a nitrogen atmosphere over a period of 30 min at -78°C. The solution turned deep blue and was stirred at this temperature for 1 h and then for 2 h at room temperature. To this mixture, 2 ml of methanol, 10 ml of water and then 5 ml of 15% HCl (to pH ~6) were slowly added sequentially. The resulting gelatinous mixture was extracted with dichloromethane (3×15 ml). The resulting cloudy, organic phase was filtered through a celite column, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residues were chromatographed on silica gel columns or preparative TLC plates and eluted with a mixture of hexane:ethyl acetate (9:1).
On the 1,6-addition of alkylamuninium compounds to para-quinones
Z. Florjanczyk and E. Szymanska-Zachara.
J. Organomet. Chem. 259 (1983), p. 127
Procedure
The reactions were carried out under nitrogen in a vessel equipped with a stirrer and connected through a liquid seal to a burette. A toluene solution of quinone was prepared in the vessel, and a toluene solution of an organoaluminium compound or a nitromethane solution of AlCl, was then introduced with vigorous stirring. When reaction was complete, the mixture was treated with water or 1 M HCl and the organic and aqueous layers were separated. Both layers were concentrated and the products isolated from them as indicated below. 4-Ethoxyphenol was extracted with petroleum ether.
Mol ratio: quinone/organoaluminium compound = 1, solvent: toluene, 500 cm3, quinone concentration 0.07 mol 1-l; temp. -78C; time 2 h.
1,4-Benzoquinone with MeAlCl2,
Yeild 54% hydroquinone, 0% 4-Methoxyphenol
1,4-Benzoquinone with EtAlCl2,
Yeild 29% hydroquinone, 20% 4-Ethoxyphenol
1,4-Benzoquinone with Et3Al
Yeild 59% hydroquinone, 8% 4-Ethoxyphenol
Reactions of organoaluminium compounds with benzoquinone
J. Organomet. Chem. 112 (1976), p. 21
Note: Similar to above done in toluene, the yeilds suck.
Preparative electrochemical reductive methylation of ortho-hydroxy-para-benzoquinones
Tetrahedron (1997), 53(2), 469-478.
Abstract
An electrochem. methodol. for the protection of the ortho-hydroxy-para-benzoquinone functionality has been developed, by a one step formation of the arom. ethers of the reduced quinone function, improving the yields obtained for this reaction by the classical chem. methods.
Reductive methylation of quinones.
Gripenberg, Jarl; Hase, Tapio.
Acta Chem. Scand. (1963), 17(
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, 2250-2.
Journal written in English.
Abstract
Quinones with high oxidn.-redn. potentials were reductively methylated with Me2SO4 in the presence of C5H5N. Thus, 0.8 ml. Me2SO4, 5 ml. MeOH, and 0.23 ml. C5H5N refluxed 1 hr., the soln. chilled and treated with 0.3 g. p-benzoquinone (I) in 5 ml. MeOH, and the cooled (ice-salt bath) mixt. basified with 5 g. NaOH in 10 ml. MeOH and steam distd. 5 min. later gave 285 mg. 1,4-(MeO)2C6H4. Similarly, toluquinone gave 60% 2,5-(MeO)2C6H3Me, and p-mentha-3,6-diene-2,5-dione (redn. time 2 hrs.) afforded 30% 2,5-dimethoxy-p-cymene. The procedure was modified for less reactive quinones as follows: 0.3 g. 2,5-diphenylbenzoquinone, 5 g. K2CO3, 0.1 ml. C5H5N, 0.33 ml. Me2SO4, and 10 ml. MeOH refluxed 8 hrs. gave 265 mg. 2',5'-dimethoxy-p-terphenyl, m. 154°. Likewise, 1,2- and 1,4-naphthoquinone gave 10% 1,2 and 14% 1,4-dimethoxynaphthalene, resp. From reductive methylations with tetramethylbenzoquinone, 2,5-dimethoxybenzoquinone (IV), 7-isopropyl-1-methylphenanthrenequinone, and anthraquinone only unchanged quinones were recovered, while 2,5-dihydroxybenzoquinone gave IV. I added to an ice-cold soln. of 1-methylpyridinium hydroxide in H2O produced 1-methyl-2(1H)-pyridone, which indicated that quinones of high oxidn. potential could be used to oxidize alkylpyridinium hydroxides.
This might have something interesting in it
A study of an oxidative-amination method for the synthesis of aminoquinones.
Crosby, Alan H.; Lutz, Robert E.
J. Am. Chem. Soc. (1956), 78 1233-5.
Abstract
Finely powd. Cu(OAc)2.H2O (20 g.), 0.6 mole of the appropriate secondary amine, and 300 cc. MeOH stirred, the soln. flushed with O and treated cautiously with cooling at 20-30° with 10.8 g. 1,4-benzoquinone in 200 cc. MeOH, the mixt. cooled after the O absorption ceased (30-60 min.) to 10° and filtered (if the product was sparingly sol.) or evapd. at room temp. in vacuo, the residue treated with 300 cc. Et2O and 22 cc. 96% H2SO4 and 500 cc. H2O, the aq. layer extd. with Et2O, the combined Et2O layer and ext. evapd., the residue extd. with hot iso.ovrddot.octane, and the ext. evapd. in an air stream gave the corresponding 2,5-di(substituted-amino)-1,4-quinone (substituted-amino group, phys. appearance, cor. m.p., and % yield given): Et2N (I), red needles, 112-14° (iso.ovrddot.octane-EtOH), 44; morpholino (II), red needles, 232-8° (decompn.) (from dioxane), 96 [II was also obtained by heating 2,5-dimethoxy-1.4-benzoquinone (III) in excess morpholine]; piperidino (IIIa), purple-red cubes, 179-80° (from EtOH) (decompn.), 89; Me(Me2CH)N (IV), red needles, 111-13° (from iso.ovrddot.octane-EtOH), 48; Pr2N, red clusters, 55-7° (from iso.ovrddot.octane), 45; Bu2N, red waxy solid, 45-7° (from iso.ovrddot.octane), 55; Me(PhCH2)N, red blades, 176-8° (from EtOH-dioxane) (decompn.), 86. The appropriate quinone in a min. of Ac2O treated with several cc. dry Et3N and excess Zn dust, the mixt. warmed with stirring and filtered hot, and the filtrate cooled and poured into H2O or extd. with Et2O gave the corresponding N-substituted 2,5-diaminohydroquinone diacetates (substituted amino group, crystal form, m.p., and % yield given): Et2N, blades, 48-50° (from iso.ovrddot.octane), 40; morpholino, -, 242-3° (from EtAc-Me3COH), 58; piperidino, tabular, 166-7° (from EtOAc), 90; Me(Me2CH)N, plates, 117-19° (from iso.ovrddot.octane-EtOAc), 77; Pr2N, plates, 71-2° (from iso.ovrddot.octane), 35; Bu2N, clusters, 50-1° (from iso.ovrddot.octane), 32; Me(Ph CH2)N, prisms, 153-5° (from dioxane-EtOAc), 80. 2,5-Diethoxy-1,4-benzoquinone (V) (1.0 g.) and 4.0 g. iso-Pr2NH(VI) in 100 cc. Me3COH refluxed 3 days and evapd., and the brown residue (0.8 g.) recrystd. from 20 cc. EtOH gave 0.4 g. unchanged V, m. 186-8°. V (2.0 g.) and 4.0 g. VI in 100 cc. MeOH refluxed 1 hr. gave 1.5 g. 2,5-dimethoxyquinone, converted to 2,5-dimethoxyhydroquinone diacetate (VII). Finely powd., crude III acetylated reductively at 90° gave VII, m. 186-8° (from Ac2O, MeOH, and iso-PrOH). Finely powd. IIIa (5.5 g.) heated 0.5 hr. with 30 cc. 96% H2SO4 in 120 cc. H2O at 50-5° and extd. continuously with Et2O, and the ext. worked up gave 1.4 g. 2,5-dihydroxy-1,4-benzoquinone(VIII), light yellow crystals which slowly became yellow-orange on standing, also obtained from IV in the same manner. I (1.0 g.) in 80 cc. boiling 2N NaOH dild. with dioxane to soln., refluxed 1 hr., cooled, acidified, and extd. with Et2O, the ext. evapd., the residue extd. with hot C6H6, and the C6H6 evapd. gave VIII. VIII (0.7 g.) in 50 cc. abs. EtOH treated with 1 cc. Et2O-BF3, allowed to stand 5 hrs., distd. to beginning crystn., and cooled to room temp. gave 0.3 g. V, m. 188-9°. VIII (1.4 g.) treated 5 min. with 20 cc. Ac2O and 3 cc. Et2O-BF3 and poured into H2O gave 1.0 g. 2,5-diacetoxy-1,4-benzoquinone, canary-yellow plates, m. 150-5° (decompn.), which was converted by reductive acetylation to 1,2,4,5-tetraacetoxybenzene (IX). VIII (1.4 g.), 30 cc. Ac2O, and 15 cc. Et3N subjected to a reductive acetylation and cooled to -20° gave 1.0 g. IX, m. 228-30°, which deacetylated with HCl in MeOH and methylated with Me2SO4 yielded 1,2,4,5-tetramethoxybenzene, m. 101-2°. Cu(OAc)2 (10 g.), 21.3 g. piperidine, and 150 cc. MeOH treated with 7.9 g. 1,4-naphthoquinone in 400 cc. MeOH, the MeOH evapd., the residue treated with 8 cc. 96% H2SO4 in 250 cc. H2O, and the product recrystd. from iso.ovrddot.octane and then from 25 cc. MeOH gave 10.5 g. 2-(1-piperidyl)-1,4-naphthoquinone, m. 94-6° (from iso.ovrddot.octane), which subjected to a reductive acetylation yielded 78% 2-(1-piperidyl)-1,4-naphthoquinone diacetate, m. 130-1° (from EtOAc).
Derivatives of pentahydroxybenzene and a synthesis of pedicellin.
Baker, Wilson.
J. Chem. Soc. (1941)
Abstract
The derivs. of C6H(OH)5 which have been isolated from plant sources are listed and 4 methods of synthesis are reviewed. 1,2,3-C6H3(OH)3 (126 g.), methylated at 18-22°, gives 155 g. of the tri-Me ether; oxidation with HNO3 in EtOH at 50° gives 124 g. of 2,6-(MeO)2C6H2O2; reduction with Na2S2O4 gives 110 g. of the quinol which with Me2SO4 and NaOH in EtOH yields 54 g. of crude 1,2,3,5-C6H2(OMe)4 (I). Addn. of 50 g. of I to 50 g. AlCl3 in 250 cc. ether with cooling, followed by 25 g. AcCl during 1 hr. with cooling and stirring for a further 6 hrs., gives 70% of 2,3,4,6-HO(MeO)3C6HAc (II), m. 103-5°; oxidation of 22.6 g. of II with 142 cc. 3% H2O2 in dil. NaOH at 20° gives 12.3 g. of 1,2-dihydroxy-3,4,6-trimethoxybenzene (III), m. 82° (di-Ac deriv., m. 147°). Methylation of 10 g. of III gives about 10 g. of C6H(OMe)5 (IV), b14 150°, b21 167°, m. 58-9°. Gallacetophenone (67.2 g.) with Me2SO4 and K2CO3 in C6H6, refluxed 6 hrs., gives 51 g. of 2,3,4-HO(MeO)2C6H2Ac (V), m. 77°, and about 10 g. of the tri-Me ether, b20 178°; oxidation of 20.2 g. of V with K2S2O8 in aq. NaOH gives 6.6 g. of 2,5,3,4-(HO)2(MeO)2C6HAc (VI), m. 119°. VI (21.2 g.) yields with Me2SO4 and K2CO3 in C6H6 (refluxing 14 hrs.) 16.5 g. of 2-hydroxy-3,4,5-trimethoxyacetophenone (VII), pale yellow, m. 86°; Cu(OAc)2 in dil. EtOH gives a green co.ovrddot.ordinated Cu deriv.; NaOH gives a bright yellow soln. and alc. FeCl3 gives a deep slate-blue color. Oxidation of 11.3 g. of VII with alk. H2O2 yields 7.8 g. of 1,2-dihydroxy-3,4,5-trimethylbenzene (VIII), m. 90-1°; dil. NaOH gives a light green soln. turning to yellow; aq. FeCl3 yields an orange color turning to cherry-red; excess FeCl3 gives a deep brown soln.; di-Ac deriv., m. 77°. VIII with Me2SO4 yields V. 2,5,4,6-(HO)2(MeO)2C6HAc (8 g.), Me2SO4 and K2CO3 in C6H6, refluxed 14 hrs., give 1.3 g. of 2-hydroxy-4,5,6-trimethoxyacetophenone, bright yellow oil, b27 184-6°; the Cu deriv. is green; FeCl3 yields a deep violet-gray color; oxidation with alk. H2O2 gives VIII. III (1 g.) in 20 cc. H2O, treated dropwise at 10° with 2 g. FeCl3 in 10 cc. H2O, gives after 4 hrs. 0.65 g. of 2-hydroxy-3,6-dimethoxy-1,4-benzoquinone (IX), dark red, m. about 208°; from AcOH it seps. as scarlet plates which appear to contain solvent of crystn.; in dil. NaOH IX gives an intensely purple-red soln. from which it is pptd. unchanged by acid. IX and Ac2O with a little H2SO4 give the 2-Ac deriv. (X), bright yellow, m. 147°; this also results on boiling with Ac2O or with Ac2O and C5H5N at 40° or at room temp. Reduction of X with Na2S2O4 in dil. EtOH at 60° gives 2-acetoxy-3,6-dimethoxyquinol, m. 151°; methylation gives IV; boiling Ac2O gives the diacetate, m. 114-15°. Reduction of IX yields 2-hydroxy-3,6-dimethoxyquinol, m. 144°; FeCl3 gives a red soln. which, if in sufficient concn., deposits IX. II. (11.2 g.) and K2S2O8 in dil. alkali, followed by hydrolysis, give 3.5 g. of 2,5-dihydroxy-3,4,6-trimethoxyacetophenone, yellow, m. 116-17°; FeCl3 in EtOH gives an apple-green color; methylation of 5.5 g. gives 4.8 g. of 2,3,4,5,6-pentamethoxyacetophenone (XI), b13 163°, m. 43°. XI (0.7 g.), 0.14 g. Na and 2.1 g. BzOEt, heated 1.5 hrs. at 125°, give 0.08 g. of 2,3,4,5,6-pentamethoxydibenzoylmethane, pale yellow, m. 91°; FeCl3 gives a cherry-red color. XI and BzH with EtONa give 2,3,4,5,6-pentamethoxyphenyl styryl ketone (pedicellin), m. 93°. IV (5 g.) and then 5 g. AcCl, added to 5 g. AlCl3 in 25 cc. ether, give after boiling with dil. HCl 1.7 g. of 2-hydroxy-3,4,5,6-tetramethoxyacetophenone (XII), bright yellow oil, b14 183°; it is very slightly volatile with steam; aq. and alc. FeCl3 give intense brown and deep brownish-green colors, resp.; Cu gives a green co.ovrddot.ordinate Cu deriv. Oxidation of XII with alk. H2O2 at 46° gives a crude 1,2-(HO)2C6(OMe)4 which with Me2SO4 and KOH gives C6(OMe)6, m. 81°. In the demethylation of o-MeO ketones by AlCl3 in ether, the MeO groups must be activated by CO groups in either the o- or p-positions. Demethylation in the p-position takes place much less readily than in the o-position but has been observed in the case of 2,3,4-(MeO)3C6H2Ac which by the prolonged action of boiling ethereal AlCl3 yields 3,2,4-MeO(HO)2C6H2Ac. The remarkably inert nucleus of 1,2,4,5-C6H2(OMe)4 is not attacked by AlCl3 and AcCl in ether.
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