Арилнафтохінони. 3. Синтез та реакції 2-арил-2,3-дигідро-2,3-епокси-6,7-диметил-1,4-нафтохінонів

Abstract

Окисненням 2-арил-6,7-диметил-1,4-нафтохінонів 1–6 (арил = C6H5 (1), 4-MeC6H4 (2), 4-EtOC6H4 (3), 4-FC6H4 (4), 3-ClC6H4 (5), 2,5-Cl2C6H3 (6)) пероксидом водню одержано 2-арил-2,3-дигідро-2,3-епокси-6,7-диметил-1,4-нафтохінони 7–12. Виявлено умови розкриття епоксидного циклу дією N-нуклеофільних реагентів, внаслідок чого Туворюються з добрими виходами відповідні амінопохідні 1,4-нафтохінону 13–18. Досліджено реакції епокси-1,4-нафтохінонів з деякими амбідентними нуклеофілами. Ключові слова: 2-арил-1,4-бензохінони, арилнафтохінони, епокси-1,4-нафтохінони, похідні нафтохінону, амбідентні нуклеофіли.

The paper are devoted to the synthesis of epoxyarylnaphthoquinones and the studying of the oxirane ring disclosing of its. 2-Aryl-2,3-dihydro-2,3-epoxy-6,7-dimethyl-1,4-naphthoquinones 7–12 were synthesized in a high yield by the oxidation reaction of 2-aryl-6,7-dimethyl-1,4-naphthoquinones 1–6 with hydrogen peroxide in the presence of potassium carbonate. Such as the epoxidation reaction of the α,β-unsaturated ketones, reaction of quinones are occurred as a nucleophilic hydroperoxide anion addition to the C=C bond of the quinone ring with following intramolecular cyclization. Obtained epoxy-1,4-naphthoquinones were studied in the reactions of Nand S-nucleophiles. The substituted 2-R1R 2 -amino-3-aryl-6,7-dimethyl-1,4-naphthoquinones 13–18 were obtained via the reaction of amines with 2,3-epoxy-1,4-naphthoquinones 7, 12. Reaction mechanism include the formation of intermediate adduct with following water elimination. In the oxirane ring opening reactions with secondary aliphatic amines, particularly morpholine (compounds 17, 18) the yields of the aminonaphthoquinones were high. The reaction of 2,3-epoxy-1,4-naphthoquinones with potassium thiocyanate and thiourea was investigated for conversion of the oxirane to the thiirane ring. It was found that the reaction of the epoxyquinones with potassium thiocyanate leads to the C–O bond breaking and the formation of the bis-(3-aryl-6,7-dimethyl-1,4- naphthoquinone)-2,2'-sulfides 19–21 without closing the oxirane rings. Compounds with thiirane rings were not obtained. These reactions were carried out under heating of the equimolar amounts of the corresponding epoxynaphthoquinones with potassium thiocyanate in water alcohol. 6,7-Dimethyl-3-(4-methylphenyl)-1,4-dioxo-1,4-dihydronaphthalen-2-yl imidothiocarbamate 22 was formed by the reaction of the 2,3-epoxy-2,3-dihydro-6,7-dimethyl-2-(4-methylphenyl)-1,4-naphthoquinone 8 with thiourea at the room temperature in ethanol medium. The mechanisms of the epoxidation reaction of the quinones and the reaction sulfides formation 19–21 were discussed. 2-Aryl-6,7-dimethyl-1,4-naphthoquinones 1–6 were obtained via the diene synthesis by the reaction of 2- aryl-1,4-benzoquinones with 2,3-dimethyl-1,3-butadiene. The structures of the compounds 7–22 were confirmed by the 1H NMR spectroscopy and element analysis data. As a result of our studies we suggested a convenient way of epoxy-1,4-naphthoquinones synthesis, showed the considerable synthetic possibilities of the epoxycompounds, which easily opened epoxy ring under the action of nucleophilic reagents and may be used in molecular design of the naphthoquinones. Key words: 2-aryl-1,4-benzoquinones, arylnaphthoquinones, epoxy-1,4-naphthoquinones, naphthoquinone derivatives, ambident nucleophiles.

Окислением 2-арил-6,7-диметил-1,4-нафтохинонов 1–6 (арил = C6H5 (1), 4-MeC6H4 (2), 4-EtOC6H4 (3), 4-FC6H4 (4), 3-ClC6H4 (5), 2,5-Cl2C6H3 (6)) пероксидом водорода получили 2-арил-2,3-дигидро-6,7- диметил-2,3-эпокси-1,4-нафтохиноны 7–12. Определены условия раскрытия эпоксидного цикла деїствием N-нуклеофильных реагентов, вследствие чего с хорошими выходами получены соответствующие аминопроизводные 1,4-нафтохинона 13–18. Исследованы реакции эпокси-1,4-нафтохинонов с некоторыми амбидентными нуклеофилами. Ключевые слова: 2-арил-1,4-бензохиноны, арилнафтохиноны, эпокси-1,4-нафтохиноны, производные нафтохинона, амбидентные нуклеофилы.