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Azaspiro[3.3]heptanes are valuable synthetic targets for drug discovery programs. The challenges associated with the preparation and diversification of this moiety as compared to other small, saturated rings have led to limited applications of compounds containing this spirocycle. In this regard, important advances in the field of synthetic photochemistry have exploited the biradical nature of the triplet excited state of 2-isoxazoline-3-carboxylates, engaging these species in intermolecular coupling reactions under visible light irradiation. As a continuation of our program preparing F(sp3)-rich, structurally complex molecules for DNA-encoded library technology (DELT) applications via photocatalysis, we disclose herein the incorporation of unique and densely functionalized 2-oxa-1-azabicyclo[3.2.0]heptanes via [2+2] cycloaddition energy transfer sensitization, providing access to an unexplored library of azaspiro compounds, many of which include additional synthetic handles important for further functionalization of the DNA-conjugated products and for library production. [ABSTRACT FROM AUTHOR]

The site‐selective modifications of quinazolinones constitute a pivotal topic in drug discovery and material science. Herein, we describe the rhodium(III)‐catalyzed C–H amidation of 2‐aryl quinazolin‐4(3H)‐ones with a range of nitrene surrogates including dioxazolones, organic azides, and N‐methoxyamides. Complete site‐selectivity and functional group tolerance are observed. Notably, the large‐scale reaction and late‐stage functionalization highlight the synthetic potential of the developed protocol. Combined mechanistic investigations elucidate a plausible reaction mechanism of this process. [ABSTRACT FROM AUTHOR]

Rhodium(III)‐catalyzed hydroxymethylation followed by intramolecular annulation of azobenzenes using paraformaldehyde as a valuable C1‐feedstock is described. The method is readily extended to the coupling reaction between azobenzenes and trifluoroacetaldehyde. This transformation efficiently produces a range of C3‐unsubstituted and C3‐trifluoromethylated (2H)‐indazoles, which are important targets in the development of novel bioactive compounds. Excellent chemoselectivity and functional group tolerance were observed. The synthetic transformation of C3‐unsubstituted (2H)‐indazoles highlights the utility of the developed method. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Site-selective nitration of 7-azaindoles. • Use of inexpensive organic nitrating agent (t BuNO 2) • Gram-scale synthesis and reductive transformation of nitro group. • Mechanistic investigation for catalytic cycle. Abstract The site-selective C–H nitration reaction of 7-azaindoles with t -butyl nitrite under palladium catalysis is described. This protocol provides an efficient method for the construction of ortho -nitrated N -aryl-7-azaindoles with excellent site-selectivity and functional group compatibility. The formed 7-azaindole derivatives can be readily transformed into 7-azaindoles containing an aniline functional group under palladium-catalyzed hydrogenation conditions. [ABSTRACT FROM AUTHOR]

The rhodium(iii)-catalyzed cross-coupling reaction of 8-methylquinolines with a range of allylic alcohols in water is described. This approach leads to the synthesis of various γ-quinolinyl carbonyl compounds, which are synthetically useful precursors for the construction of bioactive tetrahydroquinoline and azasteroid derivatives. [ABSTRACT FROM AUTHOR]

Cover Feature: Site-Selective C-H Amidation of 2-Aryl Quinazolinones Using Nitrene Surrogates (Eur. J. Org. B The Cover Feature b shows the rhodium(III) and iridium(III)-catalyzed C-H amidation reaction of 2-aryl quinazolin-4(3 I H i )-ones with a range of nitrene surrogates including dioxazolones dioxazolones, organic azides, and I N i -methoxyamides through I N i -assisted C-H activation. More information can be found in the Full Paper by S. Hong, I. S. Kim et al. GLO:5AG/13dec20:ejoc202001294-toc-0001.jpg PHOTO (COLOR): . gl B The Cover Feature b shows the rhodium(III) and iridium(III)-catalyzed C-H amidation reaction of 2-aryl quinazolin-4(3 I H i )-ones with a range of nitrene surrogates including dioxazolones dioxazolones, organic azides, and I N i -methoxyamides through I N i -assisted C-H activation. [Extracted from the article]

The direct methylation of N‐heterocycles is an important transformation for the advancement of pharmaceuticals, agrochemicals, functional materials, and other chemical entities. Herein, the unprecedented C(sp2)‐H methylation of iminoamido heterocycles as nucleoside base analogues is described. Notably, trimethylsulfoxonium salt was employed as a methylating agent under aqueous conditions. A wide substrate scope and excellent level of functional‐group tolerance were attained. Moreover, this method can be readily applied to the site‐selective methylation of azauracil nucleosides. The feasibility of gram‐scale reactions and various transformations of the products highlight the synthetic potential of the developed method. Combined deuterium‐labeling experiments aided the elucidation of a plausible reaction mechanism. [ABSTRACT FROM AUTHOR]

The direct methylation of N‐heterocycles is an important transformation for the advancement of pharmaceuticals, agrochemicals, functional materials, and other chemical entities. Herein, the unprecedented C(sp2)‐H methylation of iminoamido heterocycles as nucleoside base analogues is described. Notably, trimethylsulfoxonium salt was employed as a methylating agent under aqueous conditions. A wide substrate scope and excellent level of functional‐group tolerance were attained. Moreover, this method can be readily applied to the site‐selective methylation of azauracil nucleosides. The feasibility of gram‐scale reactions and various transformations of the products highlight the synthetic potential of the developed method. Combined deuterium‐labeling experiments aided the elucidation of a plausible reaction mechanism. [ABSTRACT FROM AUTHOR]

The direct utilization of simple and abundant feedstocks in carbon‐carbon bond‐forming reactions to embellish sp3‐enriched chemical space is highly desirable. Herein, we report a novel photochemical deoxygenative hydroalkylation of unactivated alkenes with readily available carboxylic acid derivatives. The reaction displays broad functional group tolerance, accommodating carboxylic acid‐, alcohol‐, ester‐, ketone‐, amide‐, silane‐, and boronic ester groups, as well as nitrile‐containing substrates. The reaction is operationally simple, mild, and water‐tolerant, and can be carried out on multigram‐scale, which highlights the utility of the method to prepare value‐added compounds in a practical and scalable manner. The synthetic application of the developed method is further exemplified through the synthesis of suberanilic acid, a precursor of vorinostat, a drug used for the treatment of cutaneous T‐cell lymphoma. A novel mechanistic approach was identified using thiol as a nucleophilic catalyst, which forms a key intermediate for this transformation. Furthermore, electrochemical studies, quantum yield, and mechanistic experiments were conducted to support a proposed catalytic cycle for the transformation. [ABSTRACT FROM AUTHOR]

The direct utilization of simple and abundant feedstocks in carbon‐carbon bond‐forming reactions to embellish sp3‐enriched chemical space is highly desirable. Herein, we report a novel photochemical deoxygenative hydroalkylation of unactivated alkenes with readily available carboxylic acid derivatives. The reaction displays broad functional group tolerance, accommodating carboxylic acid‐, alcohol‐, ester‐, ketone‐, amide‐, silane‐, and boronic ester groups, as well as nitrile‐containing substrates. The reaction is operationally simple, mild, and water‐tolerant, and can be carried out on multigram‐scale, which highlights the utility of the method to prepare value‐added compounds in a practical and scalable manner. The synthetic application of the developed method is further exemplified through the synthesis of suberanilic acid, a precursor of vorinostat, a drug used for the treatment of cutaneous T‐cell lymphoma. A novel mechanistic approach was identified using thiol as a nucleophilic catalyst, which forms a key intermediate for this transformation. Furthermore, electrochemical studies, quantum yield, and mechanistic experiments were conducted to support a proposed catalytic cycle for the transformation. [ABSTRACT FROM AUTHOR]

In this study, we examine the site-selctive iridium(III)-catalyzed C–H amidation between 2-aryl azlactones and acyl azides. This transformation produces a range of ortho-amidated azlactones, which act as precursors for the synthesis of chiral amino acids via organocatalyzed ring-opening reactions. To test its effectiveness, the method developed is applied to the late-stage C–H amidation of complex drug molecules. The isolation of an iridacycle species supports a proposed reaction pathway. [ABSTRACT FROM AUTHOR]

The success of cancer chemotherapy is limited by multidrug resistance (MDR), which is mainly caused by P-glycoprotein (P-gp) overexpression. In the present study, we describe a novel microtubule inhibitor, 5-(N-methylmaleimid-3-yl)-chromone (SPC-160002), that can be used to overcome MDR. A synthetic chromone derivative, SPC-160002, showed a broad spectrum of anti-proliferative effects on various human cancer cells without affecting P-gp expression and its drug efflux function. Treatment with SPC-160002 arrested the cell cycle at the M phase, as evidenced using fluorescence-activated cell sorting analysis, and increased the levels of mitotic marker proteins, including cyclin B, pS10-H3, and chromosomal passenger complex. This mitotic arrest by SPC-160002 was mediated by promoting and stabilizing microtubule polymerization, similar to the mechanism observed in case of taxane-based drugs. Furthermore, SPC-160002 suppressed the growth and sphere-forming activity of cancer stem cells. Our data herein strongly suggest that SPC-160002, a novel microtubule inhibitor, can be used to overcome MDR and can serve as an attractive candidate for anticancer drugs. [ABSTRACT FROM AUTHOR]

The ability to alkylate pyridines and quinolines is important for their further development as pharmaceuticals and agrochemicals, and for other purposes. Herein we describe the unprecedented reductive alkylation of pyridine and quinoline N‐oxides using Wittig reagents. A wide range of pyridine and quinoline N‐oxides were converted into C2‐alkylated pyridines and quinolines with excellent site selectivity and functional‐group compatibility. Sequential C−H functionalization reactions of pyridine and quinoline N‐oxides highlight the utility of the developed method. Detailed labeling experiments were performed to elucidate the mechanism of this process. [ABSTRACT FROM AUTHOR]

Abstract: The ability to alkylate pyridines and quinolines is important for their further development as pharmaceuticals and agrochemicals, and for other purposes. Herein we describe the unprecedented reductive alkylation of pyridine and quinoline N‐oxides using Wittig reagents. A wide range of pyridine and quinoline N‐oxides were converted into C2‐alkylated pyridines and quinolines with excellent site selectivity and functional‐group compatibility. Sequential C−H functionalization reactions of pyridine and quinoline N‐oxides highlight the utility of the developed method. Detailed labeling experiments were performed to elucidate the mechanism of this process. [ABSTRACT FROM AUTHOR]

The rhodium(III)-catalyzed cross-coupling reaction between N-sulfonyl aldimines and various olefins such as maleimides, fumarates, maleates, α,β-unsaturated ketones, acrylate and nitroalkenes is described. This transformation efficiently leads to the diastereoselective synthesis of pharmacologically privileged 1-aminoindane derivatives via the C−H alkylation followed by subsequent intramolecular cyclization. Notably, single diastereomers in all cases were observed, and the relative stereochemistry of products was confirmed by the X-ray crystallographic data. [ABSTRACT FROM AUTHOR]

The rhodium(III)-catalyzed site-selective C−H alkylation of azobenzenes and internal olefins, such as maleimides, maleates and fumarates, followed by reductive intramolecular cyclization is described. A cationic rhodium catalyst in the presence of acetic acid additive in dichloroethane solvent was found to be the optimal catalytic system for the construction of ortho-alkylated azobenzenes, which smoothly underwent the intramolecular cyclization leading to the formation of C3-functionalized oxindoles in the presence of zinc powder and acetic acid. The formed oxindole scaffold could be an important asset towards the development of novel bioactive compounds. [ABSTRACT FROM AUTHOR]

The rhodium(III)-catalyzed tandem C-H olefination and cyclization of benzamides with various alkenes is described. This protocol provides direct access to highly substituted phthalides, which are known as crucial frameworks of biologically active compounds. In particular, the amide directing group containing a benzimidazole group facilitates the activation of aromatic ortho-C-H bonds leading to olefination intermediates, and is spantaneously converted into an acid moiety, which can further undergo the intramolecular annulation process. [ABSTRACT FROM AUTHOR]

An abstract of the study "Synthesis of Phthalides Through Tandem Rhodium-Catalyzed C-H Olefination and Annulation of Benzamides" by N. K. Mishira and colleagues is presented.