10282-57-2Relevant articles and documents
Selectivities in Reactions of Organolithium Reagents with Aryl Bromides Which Bear Proton-Donating Groups
Beak, Peter,Musick, Timothy J.,Liu, Chao,Cooper, Thomas,Gallagher, Donald J.
, p. 7330 - 7335 (1993)
Studies of substrates which offer an acidic hydrogen and an aryl bromide for reaction with an organolithium reagent have been carried out with a series of benzene bromo amides and bromo anilides as well as selected benzene bromo carboxylic acids, bromoanilines, and bromobenzylamines.A representative example is the reaction of N-ethyl-N-deutero-o-bromobenzamide (6-d) with 1-lithio-3-phenylpropane to give N-ethyl-o-deuterobenzamide (46percent, 94percent-d) (7-d), N-ethyl-o-bromobenzamide (6) (49percent), 3-deutero-1-phenylpropane (51percent, 92percent-d), and 1-bromo-3-phenylpropane (48percent).Product formation in this and related cases is explained by the operation of a two step sequence in which an initial deprotonation is followed by a bromine-lithium exchange which is accelerated with respect to mixing.Such a sequence is consistent with the results of deuterium labeling and with changes in product ratios on different mixing and with differently aggregated organolithium reagents.Support is provided for the operation of two pathways for the expedited bromine-lithium exchange reactions.In one pathway a high local concentration of the organolithium reagent promotes rapid reaction and in the second the exchange reaction occurs within an initially formed complex.The selectivity for removal of a bromine ortho to a lithiated carboxamide is found to be 5-8 with n-butyllithium, and satisfactory synthetic ortho selectivity is obtained for N-ethyl-2,5-dibromobenzamide with phenyllithium.
Synthesis of pyrimido[2,1-a]isoindolone and isoindolo[2,1-a]quinazolinoneviaintramolecular aza-Prins type reaction
Biswas, Subhamoy,Porashar, Bikoshita,Arandhara, Pallav Jyoti,Saikia, Anil K.
supporting information, p. 11701 - 11704 (2021/11/12)
A novel aza-Prins type cyclization reaction involvingN-acyliminium ions and amides is reported for the synthesis of tetrahydropyrimido[2,1-a]isoindole-2,6-dione and 6,6a-dihydroisoindolo[2,1-a]quinazoline-5,11-dione derivatives in excellent yields. The strategy features inexpensive reagents, mild reaction conditions, and metal-free synthesis of N-heterocyclic frameworks. Further, post-synthetic modification results in the unprecedented formation of its triazole, tetracyclic diazacyclopenta[def]phenanthrene-1,4(9a1H)-dione and carbonyl derivatives.
Organocatalyst in Direct C(sp2)-H Arylation of Unactivated Arenes: [1-(2-Hydroxyethyl)-piperazine]-Catalyzed Inter-/Intra-molecular C-H Bond Activation
Yadav, Lalit,Tiwari, Mohit K.,Shyamlal, Bharti Rajesh Kumar,Chaudhary, Sandeep
, p. 8121 - 8141 (2020/07/16)
This article describes the identification of 1-(2-hydroxyethyl)-piperazine as a new, cost-effective, highly efficient organocatalyst, which promotes both inter- A nd intra-molecular direct C(sp2)-H arylations of unactivated arenes in the presence of potassium tert-butoxide. While the inter-molecular C-H arylation of unactivated benzenes with aryl halides (Ar-X; X = I, Br, Cl) toward biaryl syntheses underwent smoothly in the presence of only 10 mol percent organocatalyst, the intra-molecular C-H arylation catalytic system composed of 40 mol percent each of the catalyst and the additive (4-dimethylaminopyridine (DMAP)). The novel catalyst was also able to perform both inter- A nd intra-molecular direct arylations simultaneously in a single pot. The mechanistic studies confirmed the involvement of aryl radical anions and proceeded via a single-electron-transfer (SET) mechanism. The large substrate scope, high functional group tolerance, competition experiments, gram-scale synthesis, and kinetic studies further highlight the importance and versatile nature of the methodology as well as the compatibility of the new catalyst. To the best of our knowledge, this is the first report on any organocatalyst that reported detailed investigations of both inter- A nd intra-molecular direct C(sp2)-H arylations of unactivated arenes in a single representation.
Palladium-catalyzed intramolecular C-H arylation of 2-halo-: N -Boc- N -arylbenzamides for the synthesis of N-H phenanthridinones
Hu, Quan-Fang,Gao, Tian-Tao,Shi, Yao-Jie,Lei, Qian,Yu, Luo-Ting
, p. 13879 - 13890 (2018/04/25)
A palladium catalyzed synthesis of N-H phenanthridinones was developed via C-H arylation. The protocol gives phenanthridinones regioselectively by one-pot reaction without deprotection. It exhibits broad substrate scope and affords targets in up to 95% yields. Importantly, it could be applied for the less reactive o-chlorobenzamides.
