- Reaction of Guaiazulene with Bromine in Hexane and in Aqueous Tetrahydrofuran
-
2-Bromoguaiazulenium bromide and 3,3-dibromo guaiazulenium bromide were obtained respectively from the reaction of guaiazulene and its 3-bromo compound with 1 equivalent of bromine in hexane at -20 deg C.The former compound afforded in methanol a mixture of guaiazulene, 3,3'-biguaiazulene, and oligomers, and gave 3-bromoguiazulene quantitatively with alkali.Dibromoguiazulenium bromide afforded with further moles of bromine in aqueous THF a mixture of guaiazulenequinone, 3-bromo-1-hydroxyquaiazulen-5-one, and a dark blue solid A in different ratios depending on the reaction conditions.
- Nozoe, Tetsuo,Shindo, Kimio,Wakabayashi, Hidetsugu,Kurihara, Teruo,Uzawa, Jun
-
-
Read Online
- Oxidation of 4,6,8-Trimethylazulene and Guaiazulene with Hydrogen Peroxide in Pyridine
-
Oxidation of 4,6,8-trimethylazulene (1) with hydrogen peroxide in pyridine at 25 deg C for 18 h gave 4,6,8-trimethyl-1,5- and -1,7-azulenequinones, their 2-(4,6,8-trimethyl-1-azulenyl) derivatives, and 2,3-dihydro-4,6- and -4,7-dimethyl-2-(4,6,8-trimethyl-1-azulenyl)-1H-inden-1-ones in much higher yields than those by autoxidation of 1 in DMF at 120 deg C.The same oxidation of guaiazulene afforded sixteen separable products, among which there were three new dimeric condensates.
- Matsubara, Yoshiharu,Morita, Masanori,Takekuma, Shin-ichi,Nakano, Tomohiro,Yamamoto, Hiroshi,Nozoe, Tetsuo
-
-
Read Online
- UNUSUAL REACTIONS OF GUAIAZULENE WITH N-BROMOSUCCINIMIDE AND SYNTHESIS OF VARIOUSLY FUNCTIONALIZED AZULENES USING THESE REACTIONS
-
Treatment of guaiazulene (Ia) with NBS in benzene gives various, side-chain-brominated compounds, but in hexane it affords exclusively 3-bromoguaiazulene (Id).Compound Id is stable in hexane at 5 deg C in the absence of oxygen, whereas in benzene it changes very rapidly to a mixture of similar compounds as those directly obtained from Ia and NBS in benzene.Possible pathways for the formation of these compounds are briefly discussed.By utilizing these reactions, various kinds of side-chain functionalized azulenes that are otherwise not available by conventional methods can be readily prepared from Ia.
- Nozoe, Tetsuo,Shindo, Kimio,Wakabayashi, Hidetsugu,Kurihara, Teruo,Ishikawa, Sumio
-
p. 991 - 1010
(2007/10/02)
-
- Facile Shifts of Bromine Atom on C-3 Position of Guaiazulene and Synthesis of Variously Functionalized Azulenes Using These Reactions
-
Treatment of guaiazulene (1) with NBS in hexane gave exclusively 3-bromo compound, while in benzene it afforded various side-chain-brominated compounds.Shifts of bromine atom catalyzed by succinimide were observed in benzene, presumably via intermolecular radical pathways.Using these reactions, various side-chain-functionalyzed derivatives of 1, including epoxy compounds, were prepared.
- Nozoe, Tetsuo,Ishikawa, Sumio,Shindo, Kimio
-
p. 353 - 356
(2007/10/02)
-
- Autoxidation of Guaiazulene and 4,6,8-Trimethylazulene in Polar Aprotic Solvent: Structural Proof for Products
-
Autoxidation of guaiazulene and 4,5,8-trimethylazulene at 100 - 120 deg C in DMF (or HMPA) respectively yielded 25 and 17 separable products, including several known compounds.Most of these new compounds were derivatives of 1,5- and 1,7-azulenequionone, 1H-inden-1-one, naphthoquinone, and benzenoid, or dimeric and trimeric forms; structures of these products were established on the basis of spectroscopic (NMR, UV, IR, and MS) and half-wave potential (E1/2) data. 1H NMR (200-MHz) parameters of various azulene derivatives are given for comparative study.Possible reaction pathways are suggested for the formation of such a wide variety of interesting products.
- Matsubara, Yoshiharu,Takekuma, Shin-ichi,Yokoi, Katsumi,Yamamoto, Hiroshi,Nozoe, Tetsuo
-
p. 1415 - 1428
(2007/10/02)
-
- OXIDATION OF AZULENE DERIVATIVES. AUTOXIDATION OF GUAIAZULENE IN A POLAR APROTIC SOLVENT
-
Autoxidation of guaiazulene at 100 deg C in N,N-dimethylformamide afforded twenty-three separable products including seven known compounds.Most of these new compounds possess highly interesting structures of azulenoquinone, inden-1-one, benzocyclobutadien
- Nozoe, Tetsuo,Takekuma, Shin-ichi,Doi, Masashi,Matsubara, Yoshiharu,Yamamoto, Hiroshi
-
p. 627 - 630
(2007/10/02)
-