66520-90-9Relevant academic research and scientific papers
Synthesis of Six-Membered Spiro Azacyclic Oxindole Derivatives via a One-Pot Process of Umpolung Allylation/Aza-Prins Cyclization
Jang, Woo Cheol,Jung, Myeongjin,Ko, Haye Min
supporting information, p. 1510 - 1515 (2021/03/03)
An unprecedented synthetic approach involving umpolung allylation/aza-Prins cyclization of N-2,2,2-trifluoroethylisatin ketimines is described. The reactions proceed smoothly with allyl bromide in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene, H2O, and trimethylsilyl bromide; this one-pot protocol allows access to six-membered spiro azacyclic oxindole derivatives in good to excellent yields. Notably, while the general aza-Prins cyclization involves amines and aldehydes, the present synthetic strategy represents the first aza-Prins cyclization that utilizes the umpolung property of N-2,2,2-trifluoroethylisatin ketimines.
Asymmetric Reductive and Alkynylative Heck Bicyclization of Enynes to Access Conformationally Restricted Aza[3.1.0]bicycles
Chi, Yonggui Robin,Huang, Xiaolei,Nguyen, Minh Hieu,Pu, Maoping,Wu, Yun-Dong,Zhang, Luoqiang,Zhou, Jianrong Steve
supporting information, p. 10814 - 10818 (2020/06/09)
Conformationally restricted azabicycles are becoming increasingly important in medicinal research. Asymmetric Heck bicyclization of enynes proceeds to give medicinally useful aza[3.1.0] and aza[4.1.0] bicycles with excellent enantioselectivity. The key organopalladium species after bicyclization can be trapped by silanes and terminal alkynes.
Syn-dihydroxylation of alkenes using a sterically demanding cyclic diacyl peroxide
Pilevar, Afsaneh,Hosseini, Abolfazl,Becker, Jonathan,Schreiner, Peter R.
, p. 12377 - 12386 (2019/10/11)
The syn-dihydroxylation of alkenes is a highly valuable reaction in organic synthesis. Cyclic acyl peroxides (CAPs) have emerged recently as promising candidates to replace the commonly employed toxic metals for this purpose. Here, we demonstrate that the structurally demanding cyclic peroxide spiro[bicyclo[2.2.1]heptane-2,4′-[1,2]dioxolane]-3′,5′-dione (P4) can be effectively used for the syn-dihydroxylation of alkenes. Reagent P4 also shows an improved selectivity for dihydroxylation of alkenes bearing β-hydrogens as compared to other CAPs, where both diol and allyl alcohol products compete with each other. Furthermore, the use of enantiopure P4 (labeled P4′) demonstrates the potential of P4′ for a metal-free asymmetric syn-dihydroxylation of alkenes.
Mild Iridium-Catalysed Isomerization of Epoxides. Computational Insights and Application to the Synthesis of β-Alkyl Amines
Cabré, Albert,Cabezas-Giménez, Juanjo,Sciortino, Giuseppe,Ujaque, Gregori,Verdaguer, Xavier,Lledós, Agustí,Riera, Antoni
supporting information, p. 3624 - 3631 (2019/07/10)
The isomerization of epoxides to aldehydes using the readily available Crabtree's reagent is described. The aldehydes were transformed into synthetically useful amines by a one-pot reductive amination using pyrrolidine as imine-formation catalyst. The reactions worked with low catalyst loadings in very mild conditions. The procedure is operationally simple and tolerates a wide range of functional groups. A DFT study of its mechanism is presented showing that the isomerization takes place via an iridium hydride mechanism with a low energy barrier, in agreement with the mild reaction conditions. (Figure presented.).
Palladium-catalyzed allylic C-H oxidation under simple operation and mild conditions
Guo, Yunlong,Shen, Zengming
supporting information, p. 3103 - 3107 (2019/03/26)
We discovered an effective and simple system (Pd/BQ/air/r.t.) for making allylic alcohols through Pd-catalyzed allylic C-H bond functionalization. This approach exhibits advantages due to its simple operation, mild conditions, and environmentally benign features. By modifying reaction conditions, it can be suitable for preparing unsaturated aldehydes, allylic esters, ethers, and amines.
Palladium-Catalyzed Regioselective Aerobic Allylic C?H Oxygenation: Direct Synthesis of α,β-Unsaturated Aldehydes and Allylic Alcohols
Li, Chunsheng,Chen, Huoji,Li, Jianxiao,Li, Meng,Liao, Jianhua,Wu, Wanqing,Jiang, Huanfeng
supporting information, p. 1600 - 1604 (2018/03/05)
A protocol for the synthesis of α,β-unsaturated aldehydes and allylic alcohols from simple allylic hydrocarbons with water via palladium-catalyzed functionalization of allylic C?H bonds was described. Molecular oxygen is utilized as the sole oxidant in this oxygenation of terminal alkenes. This protocol features good functional group compatibility, broad substrate scope, and high atom- and step-economy. Moreover, the synthetic utility of this method can be highlighted by its application to the synthesis of ibuprofen, which is a highly potent analgesic. (Figure presented.).
Traversing Steric Limitations by Cooperative Lewis Base/Palladium Catalysis: An Enantioselective Synthesis of α-Branched Esters Using 2-Substituted Allyl Electrophiles
Schwarz, Kevin J.,Pearson, Colin M.,Cintron-Rosado, Gabriel A.,Liu, Peng,Snaddon, Thomas N.
supporting information, p. 7800 - 7803 (2018/06/26)
Cooperative catalysis enables the direct enantioselective α-allylation of linear prochiral esters with 2-substituted allyl electrophiles. Critical to the successful development of the method was the recognition that metal-centered reactivity and the sourc
Enantioselective bromocyclization of allylic amides catalyzed by BINAP derivatives
Kawato, Yuji,Kubota, Akino,Ono, Hiromi,Egami, Hiromichi,Hamashima, Yoshitaka
supporting information, p. 1244 - 1247 (2015/03/14)
A highly enantioselective bromocyclization of allylic amides with N-bromosuccinimide (NBS) was developed with DTBM-BINAP as a catalyst, affording chiral oxazolines with a tetrasubstituted carbon center in high yield with up to 99% ee. By utilizing the bro
Palladium-catalyzed oxidative heck-type allylation of β,β- disubstituted enones with allyl carbonates
Jin, Weiwei,Yang, Qin,Wu, Ping,Chen, Jiping,Yu, Zhengkun
supporting information, p. 2097 - 2102 (2014/07/07)
The palladium-catalyzed oxidative Heck-type allylation of β,β-disubstituted enones, i.e., α-oxoketene dithioacetals, was efficiently realized with allyl carbonates, providing a concise route to highly functionalized dienes. The present synthetic methodology utilizes the substrate activation strategy to activate the C-H bond of β,β-disubstituted enones by introduction of a 1,2-dithiolane functionality to make the enone substrate highly polarized and thus increase its reactivity, demonstrating rare examples for transition metal-catalyzed allylic substitution of ss,ss-disubstituted enones through a Heck-type allylation process.
Solvent-dependent enantiodivergence in the chlorocyclization of unsaturated carbamates
Garzan, Atefeh,Jaganathan, Arvind,Salehi Marzijarani, Nastaran,Yousefi, Roozbeh,Whitehead, Daniel C.,Jackson, James E.,Borhan, Babak
supporting information, p. 9015 - 9021 (2013/07/26)
A remarkable solvent-controlled enantiodivergence is seen in the hydroquinidine 1,4-phthalazinediyl diether ((DHQD)2PHAL)-catalyzed chlorocyclization of unsaturated carbamates. Eyring plot analyses of this previously unreported reaction are used to probe and compare the R- and S-selective pathways. In the CHCl3/hexanes solvent system, the pro-R process shows a surprising increase in selectivity with increasing temperature. These studies point to a strongly solvent-dependent entropy-enthalpy balance between the pro-R and pro-S pathways. Two solvents, two enantiomers: Enantiodivergent hydroquinidine 1,4-phthalazinediyl diether ((DHQD) 2PHAL)-catalyzed chlorocyclization of unsaturated carbamates, controlled solely by the choice of solvent, yields oxazolidinones in high enantioselectivity (see scheme; DCDMH=1,3-dichloro-5,5-dimethyl hydantoin). The origin of the observed enantiodivergence is traced back to a solvent-selected entropy-enthalpy balance between pro-R and pro-S pathways that dictates the course of the reaction. Copyright
