3854-52-2Relevant articles and documents
Rhodium(I)-Catalyzed Enantioselective Cyclization of Enynes through Site-Selective C(sp 3)-H Bond Activation Triggered by Formation of Rhodacycle
Oonishi, Yoshihiro,Sakamoto, Shunki,Agata, Shuya,Sato, Yoshihiro
, p. 2976 - 2983 (2021)
Rhodium(I)-catalyzed enantioselective cyclization of enynes through C(sp 3)-H bond activation was investigated. It was found that the cyclization of enynes having a tert -butyl moiety on the alkene afforded a spirocyclic compound (up to 92% ee), while the cyclization of enynes having an isopropyl or an ethyl group on the alkene gave a cyclic diene (up to 98% ee). Furthermore, an intermolecular competition reaction using a deuterium-labeled substrate revealed that C(sp 3)-H bond activation was one of the key steps, having a high energy barrier, in this cyclization.
Experimental and Computational Studies of Palladium-Catalyzed Spirocyclization via a Narasaka-Heck/C(sp3or sp2)-H Activation Cascade Reaction
Wei, Wan-Xu,Li, Yuke,Wen, Ya-Ting,Li, Ming,Li, Xue-Song,Wang, Cui-Tian,Liu, Hong-Chao,Xia, Yu,Zhang, Bo-Sheng,Jiao, Rui-Qiang,Liang, Yong-Min
supporting information, p. 7868 - 7875 (2021/05/27)
The first synthesis of highly strained spirocyclobutane-pyrrolines via a palladium-catalyzed tandem Narasaka-Heck/C(sp3 or sp2)-H activation reaction is reported here. The key step in this transformation is the activation of a δ-C-H bond via an in situ generated σ-alkyl-Pd(II) species to form a five-membered spiro-palladacycle intermediate. The concerted metalation-deprotonation (CMD) process, rate-determining step, and energy barrier of the entire reaction were explored by density functional theory (DFT) calculations. Moreover, a series of control experiments was conducted to probe the rate-determining step and reversibility of the C(sp3)-H activation step.
Pd-Catalyzed Asymmetric Acyl-Carbamoylation of an Alkene to Construct an α-Quaternary Chiral Cycloketone
Liu, Min,Wang, Xing,Guo, Ziqiong,Li, Hanyuan,Huang, Wei,Xu, Hui,Dai, Hui-Xiong
supporting information, p. 6299 - 6304 (2021/08/30)
Herein, we report the palladium-catalyzed asymmetric acyl-carbamoylation of an alkene by employing thioesters as the acyl electrophiles and t-BuNC as the carbamoyl reagent, affording an α-quaternary chiral cycloketone in synthetically useful yields with excellent enantioselectivity. The reaction proceeded via asymmetric 1,2-migratory insertions of acyl-Pd into alkenes and subsequent migratory insertion of isocyanides into C(sp3)-PdII. The product could be diversified to some valuable skeletons with retention of enantiopurity, demonstrating the synthetic utility of this protocol.
Nickel-Catalyzed Asymmetric Reductive 1,2-Carboamination of Unactivated Alkenes
He, Jun,Xue, Yuhang,Han, Bo,Zhang, Chunzhu,Wang, You,Zhu, Shaolin
, p. 2328 - 2332 (2020/01/08)
Starting from diverse alkene-tethered aryl iodides and O-benzoyl-hydroxylamines, the enantioselective reductive cross-electrophilic 1,2-carboamination of unactivated alkenes was achieved using a chiral pyrox/nickel complex as the catalyst. This mild, modular, and practical protocol provides rapid access to a variety of β-chiral amines with an enantioenriched aryl-substituted quaternary carbon center in good yields and with excellent enantioselectivities. This process reveals a complementary regioselectivity when compared to Pd and Cu catalysis.
Organic base-catalysed solvent-tuned chemoselective carbotrifluoromethylation and oxytrifluoromethylation of unactivated alkenes
Yang, Ning-Yuan,Li, Zhong-Liang,Ye, Liu,Tan, Bin,Liu, Xin-Yuan
supporting information, p. 9052 - 9055 (2016/07/21)
An unprecedented and efficient organic base-catalysed highly chemoselective carbo- and oxytrifluoromethylation of unactivated alkenes with Togni's reagent was developed. The switchable chemoselectivity was tuned by simply changing the organic base catalyst and solvent. Mechanistic studies indicated that a radical cyclization pathway for carbotrifluoromethylation in DMSO and a carbocation pathway for oxytrifluoromethylation in DCE were probably involved.
Structural optimization of cyclic sulfonamide based novel HIV-1 protease inhibitors to picomolar affinities guided by X-ray crystallographic analysis
Ganguly, Ashit K.,Alluri, Sesha S.,Wang, Chih-Hung,Antropow, Alyssa,White, Alex,Caroccia, Danielle,Biswas, Dipshikha,Kang, Eunhee,Zhang, Li-Kang,Carroll, Steven S.,Burlein, Christine,Fay, John,Orth, Peter,Strickland, Corey
, p. 2894 - 2904 (2014/04/17)
Synthesis and HIV-1 protease inhibitory activity of compound 5 based on the structure of a novel cyclic sulfonamide pharmacophore has been recently disclosed from our group. X-ray crystallographic structure of 5 when bound to the HIV-1 protease defined its binding mode. The importance of the geometry of the substitution at C4-Me (S configuration) was emphasized. In the present paper we wish to disclose the design of novel inhibitors 47 and 48 based on the X-ray structure of compound 5 bound to the HIV-1 protease, their synthesis and activity against HIV-1 protease. By making changes at the C4 position and the carbamate linkage the above compounds 47 and 48 were found to be approximately one hundred fold more active compared to 5 and their Ki values are in the picomolar range. An unusual observation regarding the activity and geometry was made with compounds 51 and 52. X-ray results demonstrate that 48 and 52 bind to the same binding pocket with simultaneous change in the conformation of the cyclic sulfonamide ring.
Regioselectivity in the intramolecular heck reaction of a series of cyclic sulfonamides: An experimental and computational study
Geoghegan, Kimberly,Evans, Paul,Rozas, Isabel,Alkorta, Ibon
supporting information, p. 13379 - 13387 (2012/11/07)
Regioselectivity in the intramolecular Heck reaction of a series of N-sulfonyl-2,5-dihydro-3-substituted pyrroles was studied. These substrates are unbiased in terms of the formed ring size of the new heterocycle. Results indicate that high levels of regi
Oxyanion Orientation in Anionic Oxy-Cope Rearrangements
Lee, Eun,Lee, Yong Rok,Moon, Bongjin,Kwon, Ohyun,Shim, Mi Seong,Yun, Jae Sook
, p. 1444 - 1456 (2007/10/02)
Efficiency of chirality transfer in anionic oxy-Cope rearrangement depends solely on the orientational preference of the oxyanionic bond in the substrates with a single carbinol carbon chiral center.In chairlike transition-state conformations for the rearrangement of simplest substrates like anions generated from (E)-1-phenyl-1,5-hexadien-3-ol and (E)-1,5-heptadien-4-ol, the oxyanionic bond is more prone to adopt the pseudoaxial orientation.On the other hand, anions generated from (E)-2-methyl-1,5-heptadien-4-ol, (E)-5-tert-butyl-1-phenyl-1,5-hexadien-3-ol, and 4-(2'-methyl-1'-cyclohexenyl)-1-buten-3-ol undergo rearrangement via chairlike transition states in which the pseudoequatorial oxyanionic bond is favored.It can thus be surmized that there is a slight stereoelectronic preference for the pseudoaxial oxyanionic bond in the chairlike transition states for the rearrangement of substrates without steric constraints.Substitution at C5 of the basic 1,5-hexadien-3-ol framework of substrates, however, leads to 1,3-diaxial steric interaction in the chairlike transition states with pseudoaxial oxyanionic bond, and pseudoequatorial disposition of oxyanionic bond becomes more favorable.
Photochemistry of 1,5-hexadien-3-ones: Wavelength-dependent selectivity in intramolecular enone-olefin photoadditions
Dauben, William G.,Cogen, Jeffrey M.,Ganzer, George A.,Behar, Victor
, p. 5817 - 5824 (2007/10/02)
The photochemistry of ten 1,5-hexadien-3-ones in methanol is studied over the wavelength range of 313-366 nm, by using monochromatic light. With the goal of understanding the unusual wavelength-dependent selectivity observed for 5-methyl-1,5-hexadien-3-one (1), quantum yield measurements, structure reactivity studies, triplet sensitization, and quenching experiments are performed. While six of the ten dienones studied show selectivities that are independent of irradiation wavelength from 313 to 366 nm, four of the dienones exhibit wavelength-dependent selectivities that are similar to that observed in 1, thus establishing that 1 is not unique, as previously believed. Triplet sensitization studies suggest that the wavelength dependence results, largely, from a single-state α-cleavage reaction that competes with triplet cycloaddition. A variety of triplet quenchers were ineffective at inhibiting these reactions. Some possible mechanisms are discussed.
Reaction of N-Bromosuccinimide with Cumene Derivatives and 1,2-Dialkyl Substituted Ethylenes
Ravindranath, B.,Srinivas, P.
, p. 592 - 594 (2007/10/02)
The results of title reaction indicate that while addition of bromine to the double bonds is the main reaction in the case of aryl substituted olefins, there is a competition between radical bromination and bromine addition in the case of dialky substituted ethylenic compounds, the coures of the reaction depending on steric factors.
