- Friedel-crafts reaction of benzyl fluorides: Selective activation of C-f bonds as enabled by hydrogen bonding
-
A Friedel-Crafts benzylation of arenes with benzyl fluorides has been developed. The reaction produces 1,1-diaryl alkanes in good yield under mild conditions without the need for a transition metal or a strong Lewis acid. A mechanism involving activation of the C-F bond through hydrogen bonding is proposed. This mode of activation enables the selective reaction of benzylic C-F bonds in the presence of other benzylic leaving groups.
- Champagne, Pier Alexandre,Benhassine, Yasmine,Desroches, Justine,Paquin, Jean-Franois
-
p. 13835 - 13839
(2015/02/05)
-
- Electrochemical deallylation of α-allyl cyclic amines and synthesis of optically active quaternary cyclic amino acids
-
Electrochemical oxidation of α-allylated and α-betizylated N-acylated cyclic amines by using a graphite anode easily affords the corresponding α-methoxylated products with up to 76% yield. Ease of oxidation was affected by the type of electrode, the size
- Kirira, Peter G.,Kuriyama, Masami,Onomura, Osamu
-
experimental part
p. 3970 - 3982
(2010/07/04)
-
- Gold-catalyzed oxidative cleavage of aryl-substituted alkynyl ethers using molecular oxygen. Simultaneous degradation of C-H and single and triple carbon-carbon bonds under ambient conditions
-
We report the gold-catalyzed oxidative cleavage of aryl-substituted alkynyl ethers using molecular oxygen under ambient conditions; the transformation involves a remarkable cleavage of C-H, C-C and CC bonds simultaneously.
- Das, Arindam,Chaudhuri, Rupsha,Liu, Rai-Shung
-
scheme or table
p. 4046 - 4048
(2009/12/08)
-
- Development of a novel environmentally friendly electrolytic system by using recyclable solid-supported bases for in situ generation of a supporting electrolyte from methanol as a solvent: Application for Anodic methoxylation of organic compounds
-
We have successfully developed a novel environmentally friendly electrolytic system using recyclable solid-supported bases for in situ generation of a supporting electrolyte from methanol as a solvent. It was found that solid-supported bases are electrochemically inactive at an electrode surface. It was also found that solid-supported bases dissociate methanol into methoxide anions and protons. Therefore, in the presence of solid-supported bases, it was clarified that methanol serves as both a solvent and a supporting electrolyte generated in situ. Anodic methoxylation of various compounds with solid-supported bases was carried out to provide the corresponding methoxylated products in good to excellent yields with a few exceptions. The methoxylated products and the solid-supported bases were easily separated by only filtration, and the desired pure methoxylated products were readily isolated simply by concentration of the filtrates. The separated and recovered solid-supported bases were recyclable for several times.
- Tajima, Toshiki,Fuchigami, Toshio
-
p. 6192 - 6196
(2007/10/03)
-
- Mechanistic and kinetic aspects of the direct electrochemical oxidation of 4-t-butyltoluene
-
The direct electrochemical oxidation of 4-t-butyltoluene at graphite electrodes in methanol, using NaClO4 as electrolyte, has been investigated in order to obtain an insight into the mechanism and kinetics of the anodic reactions taking place. It is shown that an increase in current density affects the product distribution, leading to a better yield of the target product 4-t-butylbenzaldehyde dimethyl acetal and a lower percentage of unknowns at the expense of an increase in electrical charge. It is suggested that oxidation takes place by two mechanisms: a direct one involving oxidation of the substrate at the electrode, and an indirect one where a pool of solvent radicals assists in the oxidation process. Further evidence is provided for reaction mechanisms in studies where the substrate loading is varied, and also where the ratio of substrate to solvent is varied; when the concentration of the substrate is high, there is evidence of the formation of dimers and other unknowns. Under certain conditions, these anodic reactions can be regarded as parallel consecutive second order reactions. The role played by the solvent is confirmed by kinetic data.
- Loyson, Peter,Gouws, Shawn,Zeelie, Ben
-
p. 125 - 131
(2007/10/03)
-
- Water-Soluble Calixarenes as New Inverse Phase-Transfer Catalysts. Their Scope in Aqueous Biphasic Alkylations and Mechanistic Implications
-
Alkylation reactions of active methylene compounds, alcohols and phenols with alkyl halides in aqueous NaOH solution can be carried out without the need for any added organic solvents in most cases. The water-soluble calix[n]arenes, which contain trimethylammoniomethyl groups on the upper rim, were used as inverse phase-transfer catalysts, resulting in the corresponding alkylated products in good to high yields. The scope of this methodology in aqueous biphasic alkylation reactions and the mechanistic implications are discussed.
- Shoichi, Shimizu,Suzuki, Takashi,Shirakawa, Seiji,Sasaki, Yasuyuki,Hirai, Choichiro
-
p. 370 - 378
(2007/10/03)
-
- Anodic Oxidation of Isopropyl and Tert-Butylbenzenes. Synthetic Routes to Certain Cyclohexa-1,4-Dienes
-
The anodic methoxylation of p-cymene and p-tert-butyltoluene afforded side-chain methoxylated products as well as nuclear-addition products.For nuclear-addition products both cis/trans isomers are possible and in both cases the cis isomer is in higher proportion than the trans one.The anodic methoxylation of 1,4-di-tert-butylbenzene afforded only nuclear-addition products and the anodic methoxylation of 1,4-di-isopropylbenzene afforded only side-chain products.A probable mechanism is provided.
- Barba, Isidoro,Tornero, Marcial
-
p. 9967 - 9976
(2007/10/02)
-
- Electrogenerated Acid-Catalyzed Reactions of Acetals, Aldehydes, and Ketones with Organosilicon Compounds, Leading to Aldol Reactions, Allylations, Cyanations, and Hydride Additions
-
Exquisite use of electrogenerated acid (EG acid) in the silicon-mediated acid-catalyzed reactions; e.g., aldol reactions, allylations, cyanations, and hydride additions is described.The aldol reaction of acetals 1 with enol trimethylsilyl ethers 3 and 1,2-bis(trimethylsiloxy)alkenes 4 gives the corresponding adducts 5 and 6, respectively.The reaction proceeds smoothly with EG acid derived from perchlorate salts such as LiClO4, n-Bu4NClO4, and Mg(ClO4)2 in dichloromethane using platinum electrodes.The amount of electricity required to complete the reaction implies a cationic process which is mediated by the trimethylsilyl moiety.This aldol reaction is further developed with unprotected carbonyl compounds 2 with 3, giving the trimethylsilyl ethers of the adducts 7.Further utility of this EG acid as a catalyst for a chain reaction is exemplified by the successful application in the following conversions: (1) The allylation of acetals 1 with allyltrimethylsilane (8) to give 9, (2) the cyanation of acetals 1 and unmasked 2 with trimethylsilyl cyanide (10) to give 11, 12, and 13, and (3) the hydride addition of acetals 1 with triethylsilane (14) to give 15.
- Torii, Sigeru,Inokuchi, Tsutomu,Takagishi, Sadahito,Horike, Hirofumi,Kuroda, Hideki,Uneyama, Kenji
-
p. 2173 - 2188
(2007/10/02)
-
- Indirect Electrooxidation (an Ex-Cell Method) of Alkylbenzenes by Recycle Use of (NH4)2Ce(NO3)6 in Various Solvent Systems
-
Indirect electrooxidation (an ex-cell method) of the side chain of alkylbenzenes has been performed by recycle use of (NH4)2Ce(NO3)6 (CAN) in various solvent systems.The side-chain oxidation of p-methoxytoluene (1) with CAN in methanol proceeds smoothly, yielding anisaldehyde (3, 94percent), while use of aqueous methanol or acetic acid resulted in a mixture of 3 and the dimeric product 4 (19-35percent) along with complex products (28-47percent).Electrooxidation of the recovered cerium(III) salts was perfomed smoothly in methanol by passing 1.1-1.2 F/mol of electricity to give a reddish methanol solution of CAN, which can be used for the next oxidation of 1.The repeated use of CAN over 10 times produced the desired 3 in over 90percent yields.Similarly, the oxidation of alkylbenzenes, bearing p-methoxy group, gave the corresponding side-chain-oxidized products.In contrast, p-tert-butyltoluene (9e) could be oxidized by heating with CAN in aqueous 50percent acetic acid at 85-90 deg C to give p-tert-butylbenzaldehyde in over 90percent yield.The regeneration of CAN after the oxidation of 9e was also accomplished by electrolysis in the aqueous 50percent acetic acid system.The reaction mechanisms in connection with the nature of CAN in various solvent systems are discussed.
- Torii, Sigeru,Tanaka, Hideo,Inokuchi, Tsutomu,Nakane, Shoji,Akada, Mitsuo,et al.
-
p. 1647 - 1652
(2007/10/02)
-