Iodine-promoted sequential C(sp3)-H oxidation and cyclization of aryl methyl ketones with 2-(2-aminophenyl)quinazolin-4(3H)-ones

An I2-promoted, metal-free protocol has been developed for the one-pot synthesis of 6-aroyl-5,6-dihydro-8H-quinazolino[4,3-b]quinazolin-8-ones from readily accessible substrates. This reaction involves the in situ sp3 C-H oxidation of aryl methyl ketones to phenylglyoxal, followed by imine formation and intramolecular nucleophilic addition, resulting in the formation of two new C-N bonds. Furthermore, the method is applicable to a wide range of aryl methyl ketones, including heterocycles and drug-derived substrates, yielding the desired products with yields ranging from 62% to 93%. Additionally, the practical utility of this approach was demonstrated through gram-scale synthesis.

Synthesis and cytotoxic evaluation of heterocyclic compounds by vinylic substitution of ketene dithioacetals

N-heterocyclic compounds are important molecular scaffolds in the search for new drugs, since most drugs contain heterocyclic moieties in their molecular structure, and some of these classes of heterocycles are able to provide ligands for two or more biological targets. Ketene dithioacetals are important building blocks in organic synthesis and are widely used in the synthesis of N-heterocyclic compounds. In this work, we used double vinylic substitution reactions on ketene dithioacetals to synthesize a small library of heterocyclic derivatives and evaluated their cytotoxic activity in breast and ovarian cancer cells, identifying two benzoxazoles with good potency and selectivity. In silico predictions indicate that the two most active derivatives exhibit physicochemical properties within the range of drug-like compounds and showed potential to interact with HDAC8 and ERK1 cancer-related targets.

Substrate-Controlled Divergent Synthesis of Benzimidazole-Fused Quinolines and Spirocyclic Benzimidazole-Fused Isoindoles

A Rh(III)-catalyzed annulation of 2-arylbenzimidazoles with α-diazo carbonyl compounds via C-H activation/carbene insertion/intramolecular cyclization is explored. The switchable product selectivity is achieved by the use of distinct α-diazo carbonyl compounds. Benzimidazole-fused quinolines are obtained through [4 + 2] annulation exclusively when 2-diazocyclohexane-1,3-diones are used, where they act as a C2 synthon. Alternatively, diazonaphthalen-1(2H)-ones merely function as a one-carbon unit synthon to generate a quaternary center through [4 + 1] cyclization to afford spirocyclic benzimidazole-fused isoindole naphthalen-2-ones. A thorough mechanistic study reveals the course of the reaction.

Synthesis of functionalized tetrahydrodibenzo[b,g][1,8]naphthyridin-1(2H)-ones through base-promoted annulation of quinoline-derived dipolarophiles and cyclic enaminones

An eco-friendly and metal-free method for the synthesis of tetrahydrodibenzo[b,g][1,8]naphthyridin-1(2H)-ones was established. Quinoline-derived dipolarophiles and cyclic enaminones as starting materials undergo a 1,4-Michael addition/SNAr tandem annulation reaction affording the target products. This approach features transition metal-free conditions, good functional group tolerance and operational simplicity.

Divergent Protocol for the Synthesis of Isoquinolino[1,2-b]quinazolinone and Isoquinolino[2,1-a]quinazolinone Derivatives

The development of robust and step-economic strategies to access structurally diverse drug-like compound collections remains a challenge. A distinct structural option that constitutes the core scaffold of many biologically significant molecules is the quinazolinone ring system. Several members of this family of privileged substructures have gained attention due to their diverse biological activities. In this context, the development of an efficient strategy for their access is needed. Herein, we report a divergent metal-free operation to access a diverse collection of C6-substituted pyrrolo[4',3',2':4,5]isoquinolino[1,2-b]quinazolin-8(6H)-one and pyrrolo[4',3',2':4,5]isoquinolino[2,1-a]quinazolin-12(6H)-one architectures. The described cascade unites Friedel-Crafts and aza-Michael addition reactions. This operationally simple protocol enables a rapid access to these scaffolds and is compatible with a wide scope of starting materials. In addition, the cascade features a promising approach for the design of unique compound libraries for drug design and discovery programs.

Acid/Base-Steered Cascade Cyclization: An Efficient One-Pot Access to Diverse Isobenzofuranone and Isoindolobenzoxazinone Derivatives

We herein report the acid/base-steered two distinct reaction pathways of 2-acylbenzoic acids with isatoic anhydrides. In the presence of Na₂CO₃, the cascade process consists of the cyclization of 2-acetylbenzoic acid and nucleophilic ring-opening reaction of isatoic anhydride to furnish isobenzofuranone derivatives with high efficiency. However, p-toluenesulfonic acid can promote the product isobenzofuranones to undergo sequential intramolecular rearrangment, nucleophilic addition and cyclization reaction to produce diverse isoindolobenzoxazinones in good yields. The synthetic utility of this method was further demonstrated by the gram-scale preparation of the desired products and the facile transformations of the resulting products.

Phenotype-based screening rediscovered benzopyran-embedded microtubule inhibitors as anti-neuroinflammatory agents by modulating the tubulin-p65 interaction

Neuroinflammation is one of the critical processes implicated in central nervous system (CNS) diseases. Therefore, alleviating neuroinflammation has been highlighted as a therapeutic strategy for treating CNS disorders. However, the complexity of neuroinflammatory processes and poor drug transport to the brain are considerable hurdles to the efficient control of neuroinflammation using small-molecule therapeutics. Thus, there is a significant demand for new chemical entities (NCEs) targeting neuroinflammation. Herein, we rediscovered benzopyran-embedded tubulin inhibitor 1 as an anti-neuroinflammatory agent via phenotype-based screening. A competitive photoaffinity labeling study revealed that compound 1 binds to tubulin at the colchicine-binding site. Structure-activity relationship analysis of 1's analogs identified SB26019 as a lead compound with enhanced anti-neuroinflammatory efficacy. Mechanistic studies revealed that upregulation of the tubulin monomer was critical for the anti-neuroinflammatory activity of SB26019. We serendipitously found that the tubulin monomer recruits p65, inhibiting its translocation from the cytosol to the nucleus and blocking NF-κB-mediated inflammatory pathways. Further in vivo validation using a neuroinflammation mouse model demonstrated that SB26019 suppressed microglial activation by downregulating lba-1 and proinflammatory cytokines. Intraperitoneal administration of SB26019 showed its therapeutic potential as an NCE for successful anti-neuroinflammatory regulation. Along with the recent growing demands on tubulin modulators for treating various inflammatory diseases, our results suggest that colchicine-binding site-specific modulation of tubulins can be a potential strategy for preventing neuroinflammation and treating CNS diseases.

Design and Synthesis of Conformationally Diverse Pyrimidine-Embedded Medium/Macro- and Bridged Cycles via Skeletal Transformation

The rigidity and flexibility of small molecules are complementary in 3-dimensional ligand-protein interaction. Therefore, the chemical library with conformational diversity would be a valuable resource for investigating the influence of skeletal flexibility on the biological system. In this regard, we designed and synthesized ten conformationally diverse pyrimidine-embedded medium/macro- and bridged cyclic scaffolds covering 7- to 14-member rings via an efficient skeletal transformation strategy. Their high conformational and shape diversity was confirmed by chemoinformatic analysis.

Metal-free dearomatization reactions of naphthol-ynamides for the divergent and enantioselective synthesis of azaspirocycles

An efficient Brønsted acid (BA) catalyzed intramolecular dearomatization cyclization of naphthol-ynamides has been developed, enabling the practical and divergent synthesis of two azaspirocycles in high yields.

Identification of Inhibitors of Cholesterol Transport Proteins Through the Synthesis of a Diverse, Sterol-Inspired Compound Collection

Cholesterol transport proteins regulate a vast array of cellular processes including lipid metabolism, vesicular and non-vesicular trafficking, organelle contact sites, and autophagy. Despite their undoubted importance, the identification of selective modulators of this class of proteins has been challenging due to the structural similarities in the cholesterol-binding site. Herein we report a general strategy for the identification of selective inhibitors of cholesterol transport proteins via the synthesis of a diverse sterol-inspired compound collection. Fusion of a primary sterol fragment to an array of secondary privileged scaffolds led to the identification of potent and selective inhibitors of the cholesterol transport protein Aster-C, which displayed a surprising preference for the unnatural-sterol AB-ring stereochemistry and new inhibitors of Aster-A. We propose that this strategy can and should be applied to any therapeutically relevant sterol-binding protein.

A Carbohydrate-based Synthetic Approach to Diverse Structurally and Stereochemically Complex Chiral Polyheterocycles

Chiral polyheterocycles are one of the most frequently encountered scaffolds in natural products and in current drugs repertoire. A carbohydrate-based diversity oriented synthetic (DOS) approach has been employed for gaining access to many structurally diverse and stereochemically complex rigid polyheterocyclic molecules with multiple chiral hydroxyl groups to enhance aqueous solubility. Inexpensive chiral pool of D-Glucose has been judiciously exploited to get access of complex chiral polyheterocyclic structures using inexpensive, common achiral reagents and domino-Knoevenagel hetero-Diels-Alder (DKHDA) reaction as one of the key synthetic tools. Stereochemistry of newly generated stereocenters of polycyclic structures are unambiguously determined through NMR and X-ray crystallographic study. A chemoinformatic comparison (PCA and PMI) with 40 branded blockbuster drugs showed that newly generated polyheterocycles have good three-dimensional scaffold diversity and most of these pass the Lipinski filter of drug-likeness.

Nature-inspired remodeling of (aza)indoles to meta-aminoaryl nicotinates for late-stage conjugation of vitamin B3 to (hetero)arylamines

Despite the availability of numerous routes to substituted nicotinates based on the Bohlmann–Rahtz pyridine synthesis, the existing methods have several limitations, such as the inevitable ortho-substitutions and the inability to conjugate vitamin B₃ to other pharmaceutical agents. Inspired by the biosynthesis of nicotinic acid (a form of vitamin B₃) from tryptophan, we herein report the development of a strategy for the synthesis of meta-aminoaryl nicotinates from 3-formyl(aza)indoles. Our strategy is mechanistically different from the reported routes and involves the transformation of (aza)indole scaffolds into substituted meta-aminobiaryl scaffolds via Aldol-type addition and intramolecular cyclization followed by C–N bond cleavage and re-aromatization. Unlike previous synthetic routes, this biomimetic method utilizes propiolates as enamine precursors and thus allows access to ortho-unsubstituted nicotinates. In addition, the synthetic feasibility toward the halo-/boronic ester-substituted aminobiaryls clearly differentiates the present strategy from other cross-coupling strategies. Most importantly, our method enables the late-stage conjugation of bioactive (hetero)arylamines with nicotinates and nicotinamides and allows access to the previously unexplored chemical space for biomedical research.

Vitamin B3 derivatives display a range of biological activities. Here, the authors report the synthesis of meta-aminoaryl nicotinates, derivatives of vitamin B3, and their late-stage conjugation with (hetero)arylamines, ultimately expanding the chemical space for biomedical research.

Rational drug design, synthesis, and biological evaluation of novel chiral tetrahydronaphthalene-fused spirooxindole as MDM2-CDK4 dual inhibitor against glioblastoma

Simultaneous inhibition of MDM2 and CDK4 may be an effective treatment against glioblastoma. A collection of chiral spirocyclic tetrahydronaphthalene (THN)-oxindole hybrids for this purpose have been developed. Appropriate stereochemistry in THN-fused spirooxindole compounds is key to their inhibitory activity: selectivity differed by over 40-fold between the least and most potent stereoisomers in time-resolved FRET and KINOMEscan® in vitro assays. Studies in glioblastoma cell lines showed that the most active compound ent-4g induced apoptosis and cell cycle arrest by interfering with MDM2 -P53 interaction and CDK4 activation. Cells treated with ent-4g showed up-regulation of proteins involved in P53 and cell cycle pathways. The compound showed good anti-tumor efficacy against glioblastoma xenografts in mice. These results suggested that rational design, asymmetric synthesis and biological evaluation of novel tetrahydronaphthalene fused spirooxindoles could generate promising MDM2-CDK4 dual inhibitors in glioblastoma therapy.

FeCl2 catalyzed direct modification of dihydropyrrolo[2,1-a]isoquinolines with phenols

A mild catalytic modification of dihydropyrrolo[2,1-a]isoquinolines with various phenols via the formation of heteroarene cation radicals as key intermediates has been developed. A range of direct cross-coupling products could be obtained in acceptable to excellent yields (up to 98%) in the presence of FeCl2.

Water-triggered union of multi-component reactions towards the synthesis of a 4H-chromene hybrid scaffold

An unprecedented union of multi-component reactions to construct pyrazole- and pyranopyrazole-adorned 4H-chromene from simple reactants in water at ambient temperature is reported. This innovative tactic has integrated two distinct four-component reactions (4CRs) that occur transiently to form four new heterocycles via ten covalent bonds in a single step.

A union of multi-component reactions to construct pyrazole- and pyranopyrazole-adorned 4H-chromene from simple reactants in water at RT is reported. 2 distinct four-component reactions occur transiently to form 4 new heterocycles via 10 covalent bonds in a single step.

Green and Facile Assembly of Diverse Fused N-Heterocycles Using Gold-Catalyzed Cascade Reactions in Water

The present study describes an AuPPh₃Cl/AgSbF₆-catalyzed cascade reaction between amine nucleophiles and alkynoic acids in water. This process proceeds in high step economy with water as the sole coproduct, and leads to the generation of two rings, together with the formation of three new bonds in a single operation. This green cascade process exhibits valuable features such as low catalyst loading, good to excellent yields, high efficiency in bond formation, excellent selectivity, great tolerance of functional groups, and extraordinarily broad substrate scope. In addition, this is the first example of the generation of an indole/thiophene/pyrrole/pyridine/naphthalene/benzene-fused N-heterocycle library through gold catalysis in water from readily available materials. Notably, the discovery of antibacterial molecules from this library demonstrates its high quality and potential for the identification of active pharmaceutical ingredients.

Synthesis of polyheterocycles via multicomponent reactions

Polyheterocycles are one of the most desired synthetic targets due to their numerous and valuable applications in various fields. Multicomponent reactions (MCRs) are highly convergent one-pot processes, in which three or more reagents are combined sequentially to construct complex products, with almost all the atoms coming from the starting reagents. In this context, the syntheses of 'heterocycles' via MCR-based processes have been reviewed a number of times. However, there is not a single review (recent or otherwise) covering the synthesis of 'polyheterocycles' via a direct MCR or via a one-pot process involving MCRs coupled to further cyclizations (via ionic, metal-catalyzed, pericyclic, or free-radical-mediated cyclizations). This issue is consequently the main topic of the present review, which considers work from the last decade. The work is categorized according to the key processes involved in the syntheses of polyheterocycles, aiming to give readers an easy understanding of this MCR-based chemistry and to provide insights for further investigations. The reaction mechanisms providing novel elements to these MCR-based methods for the synthesis of polyheterocycles are also discussed.

Facile construction of diverse polyheterocyclic scaffolds via gold-catalysed dearomative spirocyclization/1,6-addition cascade

A post-Ugi gold-catalysed chemo- and diastereo-selective cascade dearomative spirocyclization/1,6-addition sequence is disclosed for the facile synthesis of diverse fused polyheterocyclic scaffolds bearing indole, pyrrole, benzothiophene, furan or electron-rich arene cores.

A Brief Overview of Two Major Strategies in Diversity-Oriented Synthesis: Build/Couple/Pair and Ring-Distortion

In the interdisciplinary research field of chemical biology and drug discovery, diversity-oriented synthesis (DOS) has become indispensable in the construction of novel small-molecule libraries rich in skeletal and stereochemical diversity. DOS aims to populate the unexplored chemical space with new potential bioactive molecules via forward synthetic analysis. Since the introduction of this concept by Schreiber, DOS has evolved along with many significant breakthroughs. It is therefore important to understand the key DOS strategies to build molecular diversity with maximized biological relevancy. Due to the length limitations of this mini review, we briefly discuss the recent DOS plans using build/couple/pair (B/C/P) and ring-distortion strategies for the synthesis of major biologically relevant target molecules like natural products and their related compounds, macrocycles, and privileged structures.

A divergent synthetic pathway for pyrimidine-embedded medium-sized azacycles through an N-quaternizing strategy

A new divergent synthetic pathway for skeletally distinct pyrimidine-containing medium-sized azacycles was developed. Diversity-generating reactions via selective bond cleavages or migrations from N-quaternized intermediates were designed, and 14 discrete core skeletons were synthesized in an efficient manner. The skeletal diversity of the resulting molecular frameworks was confirmed by chemoinformatic analysis.

Medium-sized heterocycles have recently received significant attention because of their potential roles as modulators of protein–protein interactions, but their molecular diversity and synthetic availability are still inadequate to meet the demand. To address these issues, we developed a new divergent synthetic pathway for skeletally distinct pyrimidine-containing medium-sized azacycles. We introduced N-quaternized pyrimidine-containing polyheterocycles as novel key intermediates for diversity-generating reactions via selective bond cleavages or migrations and prepared 14 discrete core skeletons in an efficient manner. The skeletal diversity of the resulting molecular frameworks was confirmed by chemoinformatic analysis.

Preparation of Structurally Diverse Compounds from the Natural Product Lycorine

The synthesis of a 52-member compound collection from the natural product lycorine is reported, highlighted by divergent cross-coupling and substitution strategies and an unusual ring rearrangement induced by reaction with aryne intermediates.

The iridium-catalysed reductive coupling reaction of tertiary lactams/amides with isocyanoacetates

A catalytic reductive addition of isocyanoacetates to tertiary lactams/amides has been developed. This one-pot procedure involves Ir-catalysed partial reduction of lactams/amides and sequential chemoselective addition of isocyanide group in isocyanoacetates and produces 5-methoxyoxazoles in moderate to excellent yields.

Asymmetric synthesis of tetrahydroisoquinoline-fused spirooxindoles as Ras-GTP inhibitors that inhibit colon adenocarcinoma cell proliferation and invasion

We report the synthesis of a library of chiral THIQ-fused spirooxindoles. The most potent compound inhibits Ras-GTP, ultimately leading to mitochondrial apoptosis.

Catalyst-free [3 + 2] cyclization of dihydroisoquinoline imines and isatin-derived Morita–Baylis–Hillman carbonates via 1,5-electrocyclization: synthesis of tetrahydroisoquinoline-fused spirooxindoles

The incorporation of tetrahydroisoquinoline and spirooxindole frameworks has been achieved.

Generation of sulfonated 1-isoindolinones through a multicomponent reaction with the insertion of sulfur dioxide

A four-component reaction of 2-vinylbenzoic acids, aryldiazonium tetrafluoroborates, sulfur dioxide, and nitriles under photocatalysis in the presence of visible light is developed, leading to sulfonated 1-isoindolinones in moderate to good yields.

5-Ene-4-thiazolidinones - An efficient tool in medicinal chemistry

The presented review is an attempt to summarize a huge volume of data on 5-ene-4-thiazolidinones being a widely studied class of small molecules used in modern organic and medicinal chemistry. The manuscript covers approaches to the synthesis of 5-ene-4-thiazolidinone derivatives: modification of the C5 position of the basic core; synthesis of the target compounds in the one-pot or multistage reactions or transformation of other related heterocycles. The most prominent pharmacological profiles of 5-ene derivatives of different 4-thiazolidinone subtypes belonging to hit-, lead-compounds, drug-candidates and drugs as well as the most studied targets have been discussed. Currently target compounds (especially 5-en-rhodanines) are assigned as frequent hitters or pan-assay interference compounds (PAINS) within high-throughput screening campaigns. Nevertheless, the crucial impact of the presence/nature of C5 substituent (namely 5-ene) on the pharmacological effects of 5-ene-4-thiazolidinones was confirmed by the numerous listed findings from the original articles. The main directions for active 5-ene-4-thiazolidinones optimization have been shown: i) complication of the fragment in the C5 position; ii) introduction of the substituents in the N3 position (especially fragments with carboxylic group or its derivatives); iii) annealing in complex heterocyclic systems; iv) combination with other pharmacologically attractive fragments within hybrid pharmacophore approach. Moreover, the utilization of 5-ene-4-thiazolidinones in the synthesis of complex compounds with potent pharmacological application is described. The chemical transformations cover mainly the reactions which involve the exocyclic double bond in C5 position of the main core and correspond to the abovementioned direction of the 5-ene-4-thiazolidinone modification.

Strategies to diversify natural products for drug discovery

Natural product libraries contain specialized metabolites derived from plants, animals, and microorganisms that play a pivotal role in drug discovery due to their immense structural diversity and wide variety of biological activities. The strategies to greatly extend natural product scaffolds through available biological and chemical approaches offer unique opportunities to access a new series of natural product analogues, enabling the construction of diverse natural product-like libraries. The affordability of these structurally diverse molecules has been a crucial step in accelerating drug discovery. This review provides an overview of various approaches to exploit the diversity of compounds for natural product-based drug development, drawing upon a series of examples to illustrate each strategy.

Recent developments with rhodanine as a scaffold for drug discovery

INTRODUCTION

Rhodanines, as one of the 4-thiazolidinones subtypes, are recognized as privileged heterocycles in medicinal chemistry. The main achievements include the development of drug-like molecules with numerous biological activities as well as approved drugs. Among rhodanines, 5-ene-rhodanines are of special interest, and are often claimed as pan assay interference compounds due to Michael acceptor functionality. Areas covered: Herein, the synthetic protocols for rhodanines and their transformation are reviewed. Biological activity is briefly discussed as well as biotargets, mode of actions and optimization directions. Furthermore, the utilization of 5-ene-rhodanines in Michael additions are discussed while both pro and contra arguments have been outlined within medicinal chemistry application. Expert opinion: Rhodanines remain privileged heterocycles in drug discovery. They are accessible building blocks for optimization and transformation into related heterocycles, simplified analogues and fused heterocycles with a thiazolidine framework. Michael acceptor functionality, as well as the thesis about low selectivity towards biotargets of rhodanines, must be confirmed experimentally and it cannot be based on just the presence of conjugated α,β-unsaturated carbonyl. Moreover, the positive aspects of Michael acceptors must be considered as well as their multitarget properties. New criteria for target affinity must be found. In conclusion, rhodanines are generally not problematic per se.

"In Water": Organocatalyzed Diastereoselective Multicomponent Reactions toward 2-Azapyrrolizidine Alkaloid Scaffolds

Synthesis of the 2-aza analogues of pyrrolizidine and spirooxindole-2-azapyrrolizidine hybrid, a spiro-tetracyclic scaffold possessing multiple contiguous stereocenters, by an exclusive regio-, chemo-, and diastereoselective multicomponent reaction in water is reported. This logical and didactical tactic has integrated the principles of an ideal organic synthesis, privileged substructure-based diversity-oriented synthesis, and biology-oriented synthesis to access hybrid heterocyclic scaffolds.

A novel complexity-to-diversity strategy for the diversity-oriented synthesis of structurally diverse and complex macrocycles from quinine

Recent years have witnessed a global decline in the productivity and advancement of the pharmaceutical industry. A major contributing factor to this is the downturn in drug discovery successes. This can be attributed to the lack of structural (particularly scaffold) diversity and structural complexity exhibited by current small molecule screening collections. Macrocycles have been shown to exhibit a diverse range of biological properties, with over 100 natural product-derived examples currently marketed as FDA-approved drugs. Despite this, synthetic macrocycles are widely considered to be a poorly explored structural class within drug discovery, which can be attributed to their synthetic intractability. Herein we describe a novel complexity-to-diversity strategy for the diversity-oriented synthesis of novel, structurally complex and diverse macrocyclic scaffolds from natural product starting materials. This approach exploits the inherent structural (including functional) and stereochemical complexity of natural products in order to rapidly generate diversity and complexity. Readily-accessible natural product-derived intermediates serve as structural templates which can be divergently functionalized with different building blocks to generate a diverse range of acyclic precursors. Subsequent macrocyclisation then furnishes compounds that are each based around a distinct molecular scaffold. Thus, high levels of library scaffold diversity can be rapidly achieved. In this proof-of-concept study, the natural product quinine was used as the foundation for library synthesis, and six novel structurally diverse, highly complex and functionalized macrocycles were generated.

Radical cyclization of benzene-tethered 1,7-enynes with aryldiazonium tetrafluoroborates: a facile route to benzo[j]phenanthridines

A radical cyclization of benzene-tethered 1,7-enynes with aryldiazonium tetrafluoroborates in the presence of copper(ii) acetate and DABCO˙(SO₂)₂ is developed, leading to diverse benzo[j]phenanthridines.

Diversity-oriented synthetic strategy for developing a chemical modulator of protein-protein interaction

Diversity-oriented synthesis (DOS) can provide a collection of diverse and complex drug-like small molecules, which is critical in the development of new chemical probes for biological research of undruggable targets. However, the design and synthesis of small-molecule libraries with improved biological relevance as well as maximized molecular diversity represent a key challenge. Herein, we employ functional group-pairing strategy for the DOS of a chemical library containing privileged substructures, pyrimidodiazepine or pyrimidine moieties, as chemical navigators towards unexplored bioactive chemical space. To validate the utility of this DOS library, we identify a new small-molecule inhibitor of leucyl-tRNA synthetase-RagD protein-protein interaction, which regulates the amino acid-dependent activation of mechanistic target of rapamycin complex 1 signalling pathway. This work highlights that privileged substructure-based DOS strategy can be a powerful research tool for the construction of drug-like compounds to address challenging biological targets.