- Microwave-promoted Beller's synthesis of substituted phthalates
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A rapid and efficient synthesis of substituted phthalates via microwave-promoted Beller's reaction of aldehydes, amides, and dimethyl acetylenedicarboxylate is described. This one-pot, multicomponent reaction was performed under acetic anhydride-free and solvent-free conditions. Copyright Taylor & Francis Group, LLC.
- Yang, Yun-Yun,Shou, Wang-Ge,Wang, Yan-Guang
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p. 1383 - 1390
(2007/10/03)
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- Diels-Alder Reactions of 2-Pyrones with Acyclic Dienophiles and Hydrolyses of the Mono-adducts
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Diels-Alder reactions of 2-pyrone (1) with fumaronitrile and maleonitrile afforded regio- and stereo-specific mono-adducts 3a and 3b, respectively.The reaction of 1 with acrylonitrile gave a bis-adduct.The reaction of 4,6-dimethyl-2-pyrone (7) with dimethyl fumarate and dimethyl maleate at higher temperature gave benzene derivatives.The low reactivity of 7 and the instability of the mono-adducts with 7 were considered from the existence of back reaction and easy elimination of methyl formate, respectively.Hydrolyses of the mono-adducts of 2-pyrones gave polyfunctionalized cyclohexenes and elimination products generated from the preferencial trans-elimination of the leaving groups.
- Shimo, Tetsuro,Kataoka, Katsuyuki,Maeda, Ayumi,Somekawa, Kenichi
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p. 811 - 813
(2007/10/02)
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- Diels-Alder Reactions of Cyclohexadienes Derived from Decarboxylation of Photocycloadducts between 4,6-Dimethyl-2-pyrone and Cyclic Olefins
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Labile photo adducts between 4,6-dimethyl-2-pyrone and cyclic olefins reacted with second olefins to give cross adducts, and with acetylenes to afford both bis-adducts and benzene derivatives with the concurrent decarboxylation, respectively.The rea
- Shimo, Tetsuro,Matsuo, Kenji,Somekawa, Kenichi,Tsuge, Otohiko
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p. 549 - 551
(2007/10/02)
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- Studies on Diazepines. XXX. Addition Reactions of Monocyclic Diazepines with Dimethyl Acetylenedicarboxylate Involving Diazonine Intermediates
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The reaction of the 1H-1,3-diazepines (8a-c) with dimethyl acetylenedicarboxylate (DMAD) gave the 3a, 7a-dihydropyrrolopyridines (9), probably via the 1,5-diazonine intermediates 11 derived from the initially formed ? cycloadducts 10.Similarly, the 1H-1,2-diazepines (15a-c), upon treatment with DMAD, produced the 3a,7a-dihydroindazoles (20), presumably via the ? cycloadducts 18 and the 1,2-diazonines 19 successively, but the dihydroindazoles (20) further reacted with the reagent to give the dimethyl phthalates (16) and the pyrazoles (17) as the final products via the ? cycloadducts 21.These results are the first examples of the reaction of fully unsaturated seven-membered heterocyclic rings with acetylenes.Keywords--1H-1,3-diazepine; 1H-1,2-diazepine; dimethyl acetylenedicarboxylate; cycloaddition; diazonine intermediate; 3a,7a-dihydropyrrolopyridine; 3a,7a-dihydroindazole; dimethyl phthalate; pyrazole
- Kurita, Jyoji,Kakusawa, Naoki,Tsuchiya, Takashi
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p. 4706 - 4710
(2007/10/02)
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- Reactions of 1H-1,2- and 1H-1,3-Diazepines with Dimethyl Acetylenedicarboxylate
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The title reactions yield the 3a,7a-dihydropyrrolopyridines (2) and 3a,7a-dihydroindazoles (9), respectively, probably via the diazonine intermediates (4) and (8) derived from the initially formed ? cycloadducts; the indazoles (9) further react with the reagent to give the dimethyl phthalates (6) and the pyrazoles (7) via the ? cycloadducts (10).
- Kurita, Jyoji,Kakusawa, Naoki,Tsuchiya, Takashi
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p. 1880 - 1881
(2007/10/02)
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- Direct Thermal and Photochemical Generation of Silanones
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2-Silapyrans (1,2-oxasilins) are synthesized by the pyrolysis of 1-disilanyl-4-methoxy-1,3-butadienes via initial 1,5-silyl migration to afford an intermediate 1-sila-1,3-butadiene.Diels-Alder reaction of the silapyrans and perfluoro-2-butyne does not lead to isolable adducts but rather leads to apparent extrusion of silanone (R2Si=O), which is trapped by a variety of reagents.Reaction of the silapyrans and maleic anhydride provides stable adducts that extrude silanones upon either thermolysis or photolysis.No evidence could not be found for rearrangement of a silylsilanone to a siloxysilylene.
- Hussmann, Gregory,Wulff, William D.,Barton, Thomas J.
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p. 1263 - 1269
(2007/10/02)
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- Photochemical Reactions of Bicyclooctadienons
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A series of spirooxirano-substituted bicyclooctadienons have been prepared by Diels-Alder addition of dimethyl acetylenedicarboxylate to 2,4-cyclohexadienones, and their photochemistry was investigated.Upon direct exitation, they were found to aromatize by elimination of 2-carbonyloxirane which was trapped by ethanol to give ethyl glycidate.The acetophenone-sensitized reaction of bicyclooctadienones gave tricyclic isomeres whose formation by regiospecific di-?-methane rearrangement is discussed.
- Becker, Hans-Dieter,Ruge, Bernd
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p. 2189 - 2195
(2007/10/02)
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