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Other coupling reactions a Late-stage coupling of abscisic acid. b Vinyl bromide as a coupling electrophile and preparation of a large π-conjugation system.
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The concise construction of diene scaffolds is quite useful in the synthesis of polyenes. Many diene building blocks have been developed based on Suzuki, Still and Hiyama couplings. Herein, the commercially available and environmentally friendly compound dienedioic acid is used as a diene building block. Broad substrate scope, good functional group...
Citations
The highly efficient synthesis of all-carbon tetrasubstituted olefins has been a challenge for decades, especially of multi-aryl-substituted olefins which are widely used in functional organic materials and pharmaceuticals. This work presents a carbonyl-directed palladium-catalyzed consecutive arylation of terminal alkenes with aryl iodides under mild conditions, in which a series of triarylated tetrasubstituted olefins were obtained in moderate yields. Because a weak chelation effect is generally difficult to support such a thorough trifold Heck arylation, and β-trans-selective alkenyl C–H activation cannot be achieved via a twisted endo-metallocyclic intermediate, the key to success is the compatibility between several mechanisms, including Heck reaction, C–H activation and E/Z-isomerization. Here, the judicious selection of a flexible-alkyl-chain-tethered carbonyl group seems to be critical, as it provides a proper chelation effect that not only assists distal alkenyl functionalization or isomerization, but also avoids byproducts caused by other possible β-H elimination or migration. The strategy developed herein greatly streamlines the preparation of the target molecules, and the protocol covers a range of readily available terminal alkenes bearing a native directing group (i.e., aldehyde, ketone and ester) and aryl iodides.
Conjugated dienes have occupied a pivotal position in the field of synthetic organic chemistry and medicinal chemistry. They act as important synthons for the synthesis of various biologically important molecules and therefore, gain tremendous attention worldwide. A wide range of synthetic routes to access these versatile molecules have been developed in the past decades. Transition metal-catalyzed cross-dehydrogenative coupling (CDC) has emerged as one of the utmost front-line research areas in current synthetic organic chemistry due to its high atom economy, efficiency, and viability. In this review, an up-to-date summary including scope, limitations, mechanistic studies, stereoselectivities, and synthetic applications of transition metal-catalyzed double Cvinyl-H bond activation for the synthesis of conjugated dienes has been reported since 2013. The literature reports mentioned in this review have been classified into three different categories, i.e. (a) Cvinyl-Cvinyl bond formation via oxidative homo-coupling of terminal alkenes; (b) Cvinyl-Cvinyl bond formation via non-directed oxidative cross-coupling of linear/cyclic alkenes and terminal/internal alkenes, and (c) Cvinyl-Cvinyl bond formation via oxidative cross-coupling of directing group bearing alkenes and terminal/internal alkenes. Overall, this review aims to provide a concise overview of the current status of the considerable development in this field and is expected to stimulate further innovation and research in the future.
Fluorinated organic molecules have found numerous applications in medicinal chemistry, as the incorporation of fluorine often improve metabolic stability, lipophilicity and bioactivity. Although the preparation of aryl and aliphatic fluorides have been extensively investigated, alkenyl fluoride synthesis remains to be under-developed due to challenges associated with stereoselectivity control. Herein, we report a practical method for stereospecific synthesis of terminal alkenyl fluorides, and especially their deuterated analogues using an Ag-catalyzed decarboxylative protonation/deuteration strategy. The synthetic utility is demonstrated by broad substrate scope, scale-up experiment and product derivatization. DFT computations recognize bimolecular NMP coordination to Ag as the favourable mode, elucidate the mechanistic pathway, and provide in-depth insights into the origin of reactivity difference, which fully support the experimental data.
The chemical resistance of drugs against any change in their composition and studying the rate of multiwell-multichannel reactions in the liquid phase, respectively, are the important challenges of pharmacology and chemistry. In this article, we investigate two challenges together through studying drug stability against its unimolecular reactions in the liquid phase. Accordingly, multiwell-multichannel reactions based on 1,4-H shifts are designed for simplified drugs such as 3-hydroxyl-1H-pyrrol-2(5H)-one, 3-hydroxyfuran-2(5H)-one, and 3-hydroxythiophen-2(5H)-one. After that, the reverse and forward rate constants are calculated by using the Rice Ramsperger Kassel Marcus theory (RRKM) and Eckart tunneling correction over the 298–360 K temperature range. Eventually, using the obtained rate constants, we can judge drug resistance versus structural changes. To attain the goals, the potential energy surfaces of all reactions are computed by the complete basis set-quadratic Becke3 composite method, CBS-QB3, and the high-performance meta hybrid density functional method, M06-2X, along with the universal Solvation Model based on solute electron Density, SMD, due to providing more precise and efficient results for the barrier heights and thermodynamic studies. To find the main reaction pathway of the intramolecular 1,4-H shifts in the target molecules, all possible reaction pathways are considered mechanistically in the liquid phase. Also, the direct dynamics calculations that carry out by RRKM theory on the modeled pathways are used to distinguish the main reaction pathway. As the main finding of this research, the results of quantum chemical calculations accompanied by the RRKM/Eckart rate constants are used to predict the stability of drugs. This study proposes a new way to examine drug stability by the computer-aided reaction design of target drugs. Our results show that 3-hydroxyfuran-2(5H)-one based drugs are the most stable and 3-hydroxythiophen-2(5H)-one based drugs are more stable than 3-hydroxy-1H-pyrrol-2 (5H)-one based drugs in water solution.
