Chemical Science (IF: 9.556)
1. Synthesis of ethanol from aryl methyl ether/lignin, CO2 and H2
Chem. Sci., 2019, Advance Article
Researchers in China have developed a method to synthesise ethanol from CO2 and H2 and lignin, or aryl methyl ethers derived from lignin. The turnover number of ethanol was as high as 135 and ethanol was the only liquid product. This provides a new strategy to produce ethanol, which is a very important chemical, from renewable resources.
2. Reaction mechanism, norbornene and ligand effects, and origins of meta-selectivity of Pd/norbornene-catalyzed C–H activation
Chem. Sci., 2019, Advance Article
Scientists at Jiaotong University in China and Masahiro Ehara have investigated the detailed mechanism, selectivity and norbornene and ligand effects in a Pd/norbornene-catalysed meta-selective C–H activation and alkylation reaction. Although this reaction has been well used, the mechanism of the reaction is not clear. Here the authors present a thereotical study to deepen the understanding of this reaction, which will be very useful for experimental chemists.
Organic Chemistry Frontiers
1. Oxidant-controlled divergent transformations of 3-aminoindazoles for the synthesis of pyrimido[1,2-b]-indazoles and aromatic nitrile-derived dithioacetals
Org. Chem. Front., 2019, 6, 3355-3359
The oxidant-controlled divergent reactivity of 3-aminoindazoles is presented herein. Diverse functionalized pyrimido[1,2-b]-indazole derivatives were obtained with good yields via a Lewis-acid promoted [3 + 3] annulation reaction between ketene dithioacetals and 3-aminoindazoles. When the reaction was performed using the Cu/[O] catalytic system, new reactivity for the ring-opening of 3-aminoindazoles via C–N bond activation was achieved, which enables the olefinic C–H arylation of ketene dithioacetals under mild conditions.
2. Synthetic approach to skeletally diverse nitrogen heterocycles from dicyano-2-methylenebut-3-enoates
Org. Chem. Front., 2019, 6, 3321-3326
The [2 + 1], formal-[4 + 1] and [5 + 1] annulations of electron-deficient dienes with ambiphilic nitrogen reagents were developed on the basis of a similar vinylogous aza-Michael addition. These synthetic approaches enable the divergent synthesis of several interesting heterocyclic skeletons, such as vinylaziridines, pyrroline and 2-aminopyridines, from easily accessible starting materials under mild conditions.
1. Catalytic selective mono- and difluoroalkylation using fluorinated silyl enol ethers
Chem. Commun., 2019, Advance Article
The judicious incorporation of a fluoroalkyl moiety often brings about beneficial effects on the properties of bioactive molecules. Consequently, efficient methods for selective fluoroalkylation are much sought after in drug discovery. Despite significant achievements in trifluoromethylation, selective mono- and difluoroalkylation is still undeveloped. Catalytic functionalization of fluorinated silyl enol ethers (FSEEs) emerges as a fruitful approach for the diversity-oriented synthesis of value-added α-mono or difluoroalkylated ketones. In this feature article, we detail our efforts in developing catalytic selective mono- and difluoroalkylation reactions using FSEEs. Specifically, we highlight our findings such as activating FSEEs by amines for catalytic enantioselective synthesis, taking advantage of the often observed high activity of FSEEs over the non-fluorinated analogues for reaction development, and the influence of C-F‧‧‧H-X interactions on reactivity and selectivity.
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