This review covers some unique diazo compounds, the coupling partners to access various versatile functionalized nitrogen heterocycles, such as indoles, indolines, isoquinolines, isoquinolones, and ...so on. Different transition metals (such as Rh, Pd, Ru, Ir, Cu, and Co) are involved in these transformations, which involve consecutive processes: transition metal‐catalyzed cascade C–H activation/carbene insertion/intramolecular annulation.
Dearomatization reactions provide the most efficient method for the synthesis of spiro- or fused-ring systems from readily available compounds. This review summarizes the recent developments in ...dearomatization reactions of indoles, pyridines, quinolines, isoquinolines, and some other heteroaromatic compounds. The applications of these methods in total synthesis of natural products are also briefly introduced.
This review summarizes the recent developments in dearomatization reactions of indoles, pyridines, quinolines, isoquinolines, and some other heteroaromatic compounds.
The cyano group is well known as a versatile intermediate for transformations into a multitude of useful functional groups such as carboxyl, carbamoyl, aminomethyl, carbonyl, and heterocycles. ...Moreover, benzonitriles and α-aminonitriles are practical synthetic and natural scaffolds. This paper reviews catalytic methodologies for direct cyanation reactions of C–H bonds. These are classified by the cyano-group sources and are sorted into three categories: (i) organic cyano-group sources, (ii) metallic cyano-group sources, and (iii) combined cyano-group sources. This review includes all the reported methods in the literature until the beginning of 2016.
A novel copper-catalyzed direct trifluoromethylation of internal alkynes was developed, obtaining a series of trifluoromethylated coumarins in good yields. The cyclization was proposed to proceed via ...a radical mechanism under copper-catalyzed conditions with good functional group tolerance.
One-pot combination of silver triflate and proline catalysis is highly effective for the synthesis of 1,2-dihydroisoquinoline derivatives via multicomponent reactions of 2-alkynylbenzaldehydes, ...amines, and ketones.
The one‐step direct regioselective functionaliztion of inert C(sp2)–H bonds is an efficient and sustainable methodology for the synthesis of a variety of useful natural products and pharmaceutical ...intermediates. A range of functional groups have been widely used as directing group for various regioselective transformations. Among these, the weakly coordinating nitrile group has attracted much attention because it is a transformable, easily installed and readily removed directing group, which can be easily converted into a number of different functional groups, such as carboxyl, carbamoyl, aminomethyl, carbonyl, and heterocyclic functionalities. This review describes recent advances in nitrile‐directed C–H functionalizations catalyzed by palladium(II), ruthenium(II), rhodium(III) and iridium(I) catalysts. The review is divided into sections related to ortho‐, meta‐, and para‐C–H bond functionalizations, which are subdivided according to reaction type (olefination, arylation, halogenation, hydroxylation and acetoxylation).
Great progress has been made in the tandem annulation of enynes in the past few years. This review only presents the corresponding reactions of 1,3-enyne structural motifs to provide the ...functionalized pyridine and pyrrole derivatives. The functionalization reactions cover iodination, bromination, trifluoromethylation, azidation, carbonylation, arylation, alkylation, selenylation, sulfenylation, amidation, esterification, and hydroxylation. We also briefly introduce the applications of the products and the reaction mechanisms for the synthesis of corresponding N-heterocycles.
A Pd-catalyzed, meta-selective C–H arylation of nosyl-protected phenethylamines and benzylamines is disclosed using a combination of norbornene and pyridine-based ligands. Subjecting nosyl protected ...2-aryl anilines to this protocol led to meta-C–H arylation at the remote aryl ring. A diverse range of aryl iodides are tolerated in this reaction, along with select heteroaryl iodides. Select aryl bromides bearing ortho-coordinating groups can also be utilized as effective coupling partners in this reaction. The use of pyridine ligands has allowed the palladium loading to be reduced to 2.5 mol %. Furthermore, a catalytic amount of 2-norbornene (20 mol %) to mediate this meta-C–H activation process is demonstrated for the first time. Utilization of a common protecting group as the directing group for meta-C–H activation of amines is an important feature of this reaction in terms of practical applications.
The incorporation of the (trifluoromethyl)thio group into the isocoumarin scaffold through a Lewis‐acid‐mediated electrophilic cyclization reaction of 2‐(2‐alkynyl)benzoates with ...trifluoromethanesulfanylamide is reported. The transformation proceeds well in the presence of BiCl3 and BF3·Et2O under mild conditions to give 4‐(trifluoromethyl)thio‐1H‐isochromen‐1‐ones regioselectively and in good yields.
We describe a trifluoromethylthiolation/cyclization protocol for the synthesis of 4‐(trifluoromethyl)thio‐1H‐isochromen‐1‐ones through the reaction of 2‐(2‐alkynyl)benzoates with trifluoromethanesulfanylamide in good yields under mild conditions. A combination of the Lewis acids BiCl3 and BF3·Et2O serves as the activator for the transformation.
Purpose To improve diagnosis of hippocampal sclerosis (HS) in patients with mesial temporal lobe epilepsy (MTLE) by using MR fingerprinting and compare with visual assessment of T1- and T2-weighted ...MR images. Materials and Methods For this prospective study performed between April and November 2016, T1 and T2 maps were obtained and tissue segmentation performed in consecutive patients with drug-resistant MTLE with unilateral or bilateral HS. T1 and T2 maps were compared between 33 patients with MTLE (23 women and 10 men; mean age, 32.6 years; age range, 16-60 years) and 30 healthy participants (20 women and 10 men; mean age, 28.8 years; age range, 18-40 years). Differences in individual bilateral hippocampi were compared by using a Wilcoxon signed rank test, whereas the Wilcoxon rank-sum test was used for difference analysis between healthy control participants and patients with MTLE. Results The diagnosis rate (ie, ratio of HS diagnosed on the basis of a 2.5-minute MR fingerprinting examination compared with standard methods: MRI, electroencephalography, and PET) was 32 of 33 (96.9%; 95% confidence interval: 84.9%, 100%), reflecting improved accuracy of diagnosis (P = 1.92 × 10
) over routine MR examinations that had a diagnostic rate of 23 of 33 (69.7%; 95% confidence interval: 51.5%, 81.6%). The comparison between atrophic and normal-appearing hippocampus in 33 patients with MTLE and healthy control participants demonstrated that both T1 and T2 values in HS lesions were higher than those of normal hippocampal tissue of healthy participants (T1: 1361 msec ± 85 vs 1249 msec ± 59, respectively; T2: 135 msec ± 15 vs 104 msec ± 9, respectively; P < .0001). Conclusion MR fingerprinting allowed for multiparametric mapping of temporal lobe within 2.5 minutes and helped to identify lesions suspicious for HS in patients with MTLE with improved accuracy.
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