768-90-1Relevant articles and documents
Osawa
, p. 115,116 (1974)
H-coupled electron transfer in alkane C-H activations with halogen electrophiles
Fokin, Andrey A.,Shubina, Tatyana E.,Gunchenko, Pavel A.,Isaev, Sergey D.,Yurchenko, Alexander G.,Schreiner, Peter R.
, p. 10718 - 10727 (2002)
The mechanisms for the reactions of isobutane and adamantane with polyhalogen electrophiles (HHal2+, Hal3+, Hal5+, and Hal7+, Hal = Cl, Br, or I) were studied computationally at the MP2 and B3LYP levels of theory with the 6-31G** (C, H, Cl, Br) and 3-21G* (I) basis sets, as well as experimentally for adamantane halogenations in Br2, Br2/HBr, and I+Cl-/CCl4. The transition structures for the activation step display almost linear C···H···Hal interactions and are characterized by significant charge transfer to the electrophile; the hydrocarbon moieties resemble the respective radical cation structures. The regiospecificities for polar halogenations of the 3°C-H bonds of adamantane, the high experimental kinetic isotope effects (kH/kD = 3-4), the rate accelerations in the presence of Lewis and proton (HBr) acids, and the high kinetic orders for halogen (7.5 for Br2) can only be understood in terms of an H-coupled electron-transfer mechanism. The three centered-two electron (3c-2e) electrophilic mechanistic concept based on the attack of the electrophile on a C-H bond does not apply; electrophilic 3c-2e interactions dominate the C-H activations only with nonoxidizing electrophiles such as carbocations. This was shown by a comparative computational analysis of the electrophilic and H-coupled electron-transfer activation mechanisms for the isobutane reaction with an ambident electrophile, the allyl cation, at the above levels of theory.
Grinberg,Dzenitis
, (1977)
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Landa et al.
, (1955)
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Electrochemical-induced radical allylation via the fragmentation of alkyl 1,4-dihydropyridines
Chen, Xiaoping,Luo, Xiaosheng,Wang, Ping
, (2022/02/02)
Aldehydes are abundant chemical motifs presented in natural products and pharmaceuticals. As a radical precursor, its application is limited. Dihydropyridines (DHPs) can act as masked aldehydes, providing alkyl radicals under the activation of Lewis acid, heat, SET oxidant and light irradiation. Herein, we report the direct activation of 4-alkyl DHPs via single electron transfer at the anode. C–C bond homolysis at the C4-position of DHP generated the corresponding alkyl radical, which was captured subsequently by 2-phenyl and 2-ethoxy carbonyl allyl bromide. The following intramolecular elimination reaction afforded 20 different radical allylation products bearing various alkyl substituents with yields up to 92%.
Amantadine hydrochloride and preparation method thereof
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Paragraph 0065-0072; 0081-0088, (2021/03/18)
The invention discloses amantadine hydrochloride and a preparation method thereof, and relates to the technical field of amantadine hydrochloride synthesis. The method aims at solving the problems that the reaction time is too long and the yield of amantadine hydrochloride is not high. The amantadine hydrochloride is prepared from the following components, by weight: 5mmol of nitro compound, 5g ofcatalyst, 15ml of absolute ethyl alcohol, 15ml of concentrated hydrochloric acid, 15ml of hydrazine hydrate and 3ml of sodium hydroxide solution, The preparation method of amantadine hydrochloride comprises the following steps: respectively adding a nitro compound, absolute ethyl alcohol and a catalyst into a 50mL flask; in the production process of the hydrazine hydrate catalytic reduction method, no pollution is caused, the yield is high, the reaction conditions are mild, the yield of the nitro compound is 90%, the conversion rate of the nitro compound subjected to hydrazine hydrate catalytic reduction is 98.5%, the yield of the obtained amantadine hydrochloride is 89.5%, and compared with other processes, the yield is higher, the operation is simple, and the efficiency is high.
Thiourea-Mediated Halogenation of Alcohols
Mohite, Amar R.,Phatake, Ravindra S.,Dubey, Pooja,Agbaria, Mohamed,Shames, Alexander I.,Lemcoff, N. Gabriel,Reany, Ofer
, p. 12901 - 12911 (2020/11/26)
The halogenation of alcohols under mild conditions expedited by the presence of substoichiometric amounts of thiourea additives is presented. The amount of thiourea added dictates the pathway of the reaction, which may diverge from the desired halogenation reaction toward oxidation of the alcohol, in the absence of thiourea, or toward starting material recovery when excess thiourea is used. Both bromination and chlorination were highly efficient for primary, secondary, tertiary, and benzyl alcohols and tolerate a broad range of functional groups. Detailed electron paramagnetic resonance (EPR) studies, isotopic labeling, and other control experiments suggest a radical-based mechanism. The fact that the reaction is carried out at ambient conditions, uses ubiquitous and inexpensive reagents, boasts a wide scope, and can be made highly atom economic, makes this new methodology a very appealing option for this archetypical organic reaction.
