Contributors: Li, Lun, Huang, Donghui, Chen, Qing-Yun, Guo, Yong
... Abstract Tsuji–Trost reaction (Pd-catalyzed allylic alkylation) of CF3-containing esters with three electron-withdrawing groups is reported. The reactions with methyl bis(trifluoromethyl)acetate and dimethyl (trifluoromethyl)malonate were carried out with low-loading catalysts of Pd(0) and XPhos at ambient temperature in THF, giving the products in high yields. This method efficiently overcomes the β-defluorination, which is hard to control in the chemical transformation of α-trifluoromethyl carbanions, and provides versatile fluorinated compounds with quaternary carbon centers, which are highly demanded in drug discovery.
Contributors: Hu, Fangdong, Zhao, Xin, Li, Yanqiu, Feng, Lei, Ma, Chen
... Abstract A simple and efficient method was developed for the synthesis of phenoxathiin derivatives. A range of 1,2-dihaloarenes or 1-halo-2-nitroarenes reacted with 2-sulfanylphenol to give the desired products in good-to-excellent yields. It is intriguing that 1-halo-2-nitroarenes containing electron-donating groups worked well as substrates in this reaction.
Contributors: Buonomo, Joseph, Everson, Daniel, Weix, Daniel
... Abstract A simple, ligand-free synthesis of the important bipyridyl ligand 4,4′-di-tert-butyl-2,2′-bipyridine is presented. 5,5′-Bis(trifluoromethyl)-2,2′-bipyridine is also synthesized by the same protocol. The syntheses efficiently couple the parent 2-chloropyridines by a nickel-catalyzed dimerization with manganese powder as the terminal reductant.
Contributors: Sen, Indira, Kloer, Daniel, Hall, Roger, Pal, Sitaram
... Abstract A general synthetic route to six-membered cyclic N-aryl- and N-alkyl-substituted sulfonimidamides via an intramolecular ring closure of suitably functionalised acyclic sulfonimidamides is described. The structure of this new ring system was confirmed by various analytical methods and in one example by X-ray structural analysis.
Contributors: Wang, Man-Gang, Yu, Hua, Wu, Jun, Shang, Zhi-Cai
... Abstract The copper-catalyzed C–N cross-coupling of poorly nucleophilic acyclic secondary amides with sterically hindered substituted 2-halobenzoates has been demonstrated with 1,4-dimethyl-3,4-dihydro-1H-benzo[e][1,4]diazepin-5(2H)-one (DMBDO) as ligands for the first time. The protocol is effective for the synthesis of hindered tertiary amides. We also found that the alkoxycarbonyl (CO2R) group has a strong ortho-substituent effect on a Goldberg-type C–N coupling reaction.
Contributors: Gaugele, Dominik, Maier, Martin
... Abstract A synthesis of the tricyclic partly substituted core structure of palhinine A was achieved. To reach the bicyclo[2.2.2]octane motif a domino Michael reaction was employed as a key step. After Arndt–Eistert homologation and intramolecular aldol reaction the isotwistane core could be obtained after simple functional-group manipulations.
Contributors: Brusentsev, Yury, Hänninen, Mikko, Eklund, Patrik
... Abstract Methods for synthetic modifications of the natural dibenzylbutyrolactone lignan hydroxymatairesinol into chiral 1,4-diols with different lignan-derived backbones have been developed. A stepwise procedure, involving alkylation and oxidation, was shown to be successful and several highly substituted 1,4-diols were prepared. Some substituted butyrolactones resisted alkylation and led to the formation unusually stable hemiketals (butyrolactols). The formation of stable hemiketals was investigated in detail, showing that different backbone structures influence the formation and reactivity of the hemiketals.
Contributors: Everson, Daniel, Buonomo, Joseph, Weix, Daniel
... Abstract The synthesis of 2-alkylated pyridines by the nickel-catalyzed cross-coupling of two electrophiles, a 2-chloropyridine and an alkyl bromide, is described. Compared with our previously published conditions for aryl halides, this method uses a different, more rigid, bathophenanthroline ligand and is conducted at high concentration in N,N-dimethylformamide as solvent. The method displays promising functional group compatibility and the conditions are orthogonal to those for the Stille coupling.
Addition of Terminal Alkynes to Aromatic Nitriles Catalyzed by Divalent Lanthanide Amides Supported by Amidates: Synthesis of Ynones
Contributors: Ding, Hao, Lu, Chengrong, Hu, Xiaolin, Zhao, Bei, Wu, Bing, Yao, Yingming
... Abstract An efficient protocol has been established for the synthesis of conjugated ynones via addition of terminal alkynes to aromatic nitriles, which is catalyzed by novel divalent lanthanide amide complexes. All the reactions gave the products in good to excellent yields at room temperature under solvent-free conditions without any additives. The novel lanthanide amide catalysts were also synthesized and structurally characterized for the first time.
A Tandem Conjugate Addition–Intramolecular Horner–Wadsworth–Emmons Olefination Approach to the Synthesis of Cyclopentene[c]chroman-2-ones and Cyclopent-1-enecarboxylates
Contributors: Deredas, Dariusz, Huben, Krzysztof, Maniukiewicz, Waldemar, Krawczyk, Henryk
... Abstract A strategically new approach to cyclopentene[c]chroman-2-ones and cyclopent-1-enecarboxylates by tandem Michael–Horner–Wadsworth–Emmons reaction of 2,5-hexanedione with 3-(diethoxyphosphoryl)coumarins is described. The products were obtained as single diastereoisomers in high yields.