- Development of isomerization and cycloisomerization with use of a ruthenium hydride with N-heterocyclic carbene and its application to the synthesis of heterocycles
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A pure ruthenium hydride complex with N-heterocyclic carbene (NHC) ligand was efficiently generated from the reaction of a second-generation Grubbs ruthenium catalyst with vinyloxytrimethylsilane and unambiguously characterized. This ruthenium hydride complex showed high catalytic activity for the selective isomerization of terminal olefin and for the cycloisomerization of 1,6-dienes. These reactions of N-allyl-o-vinylaniline lead to novel synthetic methods for heterocycles such as indoles and 3-methylene-2,3-dihydroindoles, which are useful synthons for bioactive natural products. These procedures address an important issue in diversity-oriented synthesis.
- Arisawa, Mitsuhiro,Terada, Yukiyoshi,Takahashi, Kazuyuki,Nakagawa, Masako,Nishida, Atsushi
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p. 4255 - 4261
(2007/10/03)
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- SYNTHESIS OF 4-, 5-, 6- AND 7-SUBSTITUTED N-TOSYLINDOLES FROM SUBSTITUTED ANILINES
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4-, 5-, 6-, and 7-Substituted N-tosylindoles are prepared from N-tosylanilides, carrying 2-acetoxy-1-(isopropylthio)ethyl group at the ortho position, which can be prepared from substituted anilines and dialkyl sulfide by sigmatropic rearrangement.
- Murai, Yasushi,Kobayashi, Shougo,Inoue, Seiichi,Sato, Kikumasa
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p. 1017 - 1029
(2007/10/02)
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- Preparation of alkyl-substituted indoles in the benzene portion. Part 8. Improved practical synthesis of 4,4-dialkoxy-1-(1-arylsulfonyl-3-pyrrolyl)-1-butanone and 4-(1-arylsulfonyl-3-pyrrolyl)-4-oxobutanal, and a novel synthetic procedure for 4-alkoxyindole derivatives
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Important precursors (1 and 2) for the synthesis of 4-substituted indole derivatives were readily obtained by acid treatment of a tosylamide (13), which was prepared in a single operation by treatment of 10 with N-tosyl-N',N'-dimethylformamidine (TsN=CHNMe2). Compound (10) was effectively synthesized from nitromethane and acrolein by way of a nitro compound (15). A novel indole formation reaction from the tosyl-amide (13) to gain short access to 4-alkoxyindoles, such as 16, 17, 19, and 21 is presented.
- Utsunomiya,Muratake,Natsume
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p. 2358 - 2361
(2007/10/02)
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- Preparation of alkyl-substituted indoles in the benzene portion. Part 6. Synthetic procedure for 4-, 5-, 6-, or 7-alkoxy-and hydroxyindole derivatives
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A novel method for the preparation of indole derivatives that are alkoxy- and hydroxy-substituted in the benzene portion of the indole nucleus is described. The acid-induced cyclization reaction of (arylsulfonyl)pyrrole derivatives (4a, 4b, 5b, and 5a) in
- Fuji,Muratake,Natsume
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p. 2344 - 2352
(2007/10/02)
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- Preparation of alkyl-substituted indoles in the benzene portion. Part 7. Synthesis of (±)- and (S)-(-)-pindolol
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A new, short-step synthesis of a β-adrenergic blocking agent, pindolol, 1-(4-indolyloxy)-3-(2-propylamino)-2-propanol, is described. The acid-catalyzed indole cyclization reaction of 4-[1-(4-methylphenyl)sulfonyl-3-pyrrolyl]-4-oxobutanal (14) in the presence of (±)-3-chloro-1,2-propanediol (12) and (R)-1-O-[(4-methylphenyl)sulfonyl]glycerol (24) afforded (±)-1-chloro-3-[1-(4-methylphenyl)sulfonyl-4-indolyloxy]-2-propanol (15) and (R)-(-)-3-[1-(4-methylphenyl)sulfonyl-4-indolyloxy]-1-[(4-methylphenyl sulfonyloxy]-2-propanol (25). Reaction of these with isopropylamine and removal of the protecting group at the indole nitrogen gave (±)- and (S)-(-)-pindolol (3 and 4), thus constituting an efficient three-step synthesis of 3 and 4 from the readily available aldehyde (14).
- Fuji,Muratake,Akiyama,Natsume
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p. 2353 - 2357
(2007/10/02)
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- Palladium-Catalyzed Coupling of 2-Bromoanilines with Vinylstannanes. A Regiocontrolled Synthesis of Substituted Indoles
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The palladium-catalyzed cross-coupling reaction of aryl halides and triflates with vinylstannane reagents has been used to produce a variety of substituted indoles.The mild reaction conditions and selectivity inherent in the coupling reaction have been utilized to produce regiochemically pure 4-, 5-, and 6-substituted indoles.
- Krolski, Michael E.,Renaldo, Alfred F.,Rudisill, Duane E.,Stille, J. K.
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p. 1170 - 1176
(2007/10/02)
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