- Organocatalytic Cloke-Wilson Rearrangement: DABCO-Catalyzed Ring Expansion of Cyclopropyl Ketones to 2,3-Dihydrofurans
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An organocatalytic Cloke-Wilson rearrangement of cyclopropyl ketones to 2,3-dihydrofurans is exploited utilizing the homoconjugate addition process. With 1,4-diazabicyclo[2.2.2]octane as the catalyst, the rearrangement in DMSO at 120 °C proceeded in gener
- Zhang, Jingfang,Tang, Yuhai,Wei, Wen,Wu, Yong,Li, Yang,Zhang, Junjie,Zheng, Yuansuo,Xu, Silong
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p. 3043 - 3046
(2017/06/23)
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- Non-decarbonylative photochemical versus thermal activation of Bu4N[Fe(CO)3(NO)] - the Fe-catalyzed Cloke-Wilson rearrangement of vinyl and arylcyclopropanes
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The base metal complex Bu4N[Fe(CO)3(NO)] (TBA[Fe]) catalyzes the rearrangement of vinyl and arylcyclopropanes both under thermal or photochemical conditions to give the corresponding vinyl or aryldihydrofurans in good to excellent yi
- Lin, Che-Hung,Pursley, Dominik,Klein, Johannes E. M. N.,Teske, Johannes,Allen, Jennifer A.,Rami, Fabian,K?hn, Andreas,Plietker, Bernd
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p. 7034 - 7043
(2015/11/17)
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- Domino [3+3] annulation/ring-cleavage reactions of 1,3- bis(trimethylsilyloxy)-1,3-butadienes with 5-aryl- and 5-vinyl-3-acyl-4,5- dihydrofurans: Efficient synthesis of 5-(4-chlorobut-2-en-1-yl)- and 5-(2-aryl-2-chloroethyl)salicylates
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The domino "[3+3] cyclization-ring-opening" reactions of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with 3-acetyl-5vinyl-4, 5-dihydrofurans afforded 5-(4-halobut-2-en-1-yl)salicylates. The reactions of 1,3-bis(trimethylsilyloxy)-1,3butadienes with 3-acetyl
- Lau, Matthias,Sher, Muhammad,Villinger, Alexander,Fischer, Christine,Langer, Peter
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experimental part
p. 3743 - 3753
(2010/09/03)
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- Electronic and Steric Effects in the Addition of Electrophilic 1,3-Dicarbonylalkyl Radicals to Styrenes
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The addition reactions of 1,3-dicarbonylalkyl radicals to ring-substituted styrenes have been kinetically investigated in MeOH and/or MeCN.It has been observed that the rate effect of ring substituents is nearly identical in the reactions of MeCOCHCOMe (1), MeOCOCHCOMe (2) and MeOCOCHCOOMe (4), the ρ value, in MeOH being -0.96, -1.01 and -1.06, respectively.Since the three radicals are relatively strong oxidants and have similar reduction potentials, an important contribution of the transfer structure RCOCHCOR(1-)*CH2CHAr(1+) to the addition transition state is suggested.It has also be found that in the reactions of 1 and 4 with α-alkyl-substituted styrenes the rate of additions is strongly influenced by the nature of the alkyl group, decreasing in the order: Me > Et > i-Pr > t-Bu.The observed effects are much larger than those reported for the corresponding reactions of the nucleophilic cyclohexyl radical.It is suggested that the α-alkyl substituents exert an effect of steric inhibition of resonance thereby ring delocalization of the charge and/or unpaired electron in the transition state is significantly reduced.Delocalization may be more important in the reactions of 1 and 4 than in those of the cyclohexyl radical since it is possible that the former utilizes a transition state occurring later along the reaction coordinate and/or characterized by a larger extent of charge transfer.
- Baciocchi, Enrico,Ruzziconi, Renzo
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p. 4772 - 4778
(2007/10/02)
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