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Training algorithms to computationally plan multistep organic syntheses has been a challenge for more than 50 years 1 – 7 . However, the field has progressed greatly since the development of early programs such as LHASA 1 , 7 , for which reaction choices at each step were made by human operators. Multiple software platforms 6 , 8 – 14 are now capable of completely autonomous planning. But these programs ‘think’ only one step at a time and have so far been limited to relatively simple targets, the syntheses of which could arguably be designed by human chemists within minutes, without the help of a computer. Furthermore, no algorithm has yet been able to design plausible routes to complex natural products, for which much more far-sighted, multistep planning is necessary 15 , 16 and closely related literature precedents cannot be relied on. Here we demonstrate that such computational synthesis planning is possible, provided that the program’s knowledge of organic chemistry and data-based artificial intelligence routines are augmented with causal relationships 17 , 18 , allowing it to ‘strategize’ over multiple synthetic steps. Using a Turing-like test administered to synthesis experts, we show that the routes designed by such a program are largely indistinguishable from those designed by humans. We also successfully validated three computer-designed syntheses of natural products in the laboratory. Taken together, these results indicate that expert-level automated synthetic planning is feasible, pending continued improvements to the reaction knowledge base and further code optimization. A synthetic route-planning algorithm, augmented with causal relationships that allow it to strategize over multiple steps, can design complex natural-product syntheses that are indistinguishable from those designed by human experts.

Nucleoside analogues have proven to be highly successful chemotherapeutic agents in the treatment of a wide variety of cancers. Several such compounds, including gemcitabine and cytarabine, are the go-to option in first-line treatments. However, these materials do have limitations and the development of next generation compounds remains a topic of significant interest and necessity. Herein, we discuss recent advances in the chemical synthesis and biological evaluation of nucleoside analogues as potential anticancer agents. Focus is paid to 4′-heteroatom substitution of the furanose oxygen, 2′-, 3′-, 4′- and 5′-position ring modifications and the development of new prodrug strategies for these materials.

The development of selective reactions that utilize easily available and abundant precursors for the efficient synthesis of amines is a long-standing goal of chemical research. Despite the centrality of amines in a number of important research areas, including medicinal chemistry, total synthesis and materials science, a general, selective and step-efficient synthesis of amines is still needed. Here, we describe a set of mild catalytic conditions utilizing a single copper-based catalyst that enables the direct preparation of three distinct and important amine classes (enamines, α-chiral branched alkylamines and linear alkylamines) from readily available alkyne starting materials with high levels of chemo-, regio- and stereoselectivity. This methodology was applied to the asymmetric synthesis of rivastigmine and the formal synthesis of several other pharmaceutical agents, including duloxetine, atomoxetine, fluoxetine and tolterodine. Amines are essential in a number of research areas, but a general, selective and step-efficient synthesis has been elusive. Now, the use of a single copper catalyst to transform alkynes into enamines, α-chiral branched alkylamines, and linear alkylamines is described. These transformations have been applied in the preparation of a selection of current pharmaceutical agents.

Theories about the origin of life require chemical pathways that allow formation of life’s key building blocks under prebiotically plausible conditions. Complex molecules like RNA must have originated from small molecules whose reactivity was guided by physico-chemical processes. RNA is constructed from purine and pyrimidine nucleosides, both of which are required for accurate information transfer, and thus Darwinian evolution. Separate pathways to purines and pyrimidines have been reported, but their concurrent syntheses remain a challenge. We report the synthesis of the pyrimidine nucleosides from small molecules and ribose, driven solely by wet-dry cycles. In the presence of phosphate-containing minerals, 5′-mono- and diphosphates also form selectively in one-pot reactions. The pathway is compatible with purine synthesis, allowing the concurrent formation of all Watson-Crick bases.

The chemical modification of structurally complex fermentation products, a process known as semisynthesis, has been an important tool in the discovery and manufacture of antibiotics for the treatment of various infectious diseases. However, many of the therapeutics obtained in this way are no longer effective, because bacterial resistance to these compounds has developed. Here we present a practical, fully synthetic route to macrolide antibiotics by the convergent assembly of simple chemical building blocks, enabling the synthesis of diverse structures not accessible by traditional semisynthetic approaches. More than 300 new macrolide antibiotic candidates, as well as the clinical candidate solithromycin, have been synthesized using our convergent approach. Evaluation of these compounds against a panel of pathogenic bacteria revealed that the majority of these structures had antibiotic activity, some efficacious against strains resistant to macrolides in current use. The chemistry we describe here provides a platform for the discovery of new macrolide antibiotics and may also serve as the basis for their manufacture. A practical, fully synthetic route to macrolide antibiotics via the convergent assembly of simple chemical building blocks is described; more than 300 new macrolide antibiotic candidates have been synthesized using this approach, a number of which are active against bacterial strains that are resistant to currently used antibiotics. Towards a new breed of macrolide antibiotics Most antibacterial drugs used today are the products of semisynthesis, or partial chemical synthesis, based on the modification of natural fermentation products. Now, many of these antibiotics have been rendered ineffective by the spread of bacterial resistance. Macrolide antibiotics — macrocyclic lactones produced in streptomycetes — have been one of the most productive groups and this paper describes a practical synthetic route to macrolide antibiotics that bypasses many of the limitations of semisynthesis. Andrew Myers and colleagues describe a fully synthetic route to macrolide antibiotics via the convergent assembly of simple chemical building blocks. More than 300 new antibiotic candidates were synthesized using this approach, some of which are active against bacterial strains that are resistant to currently used antibiotics.

Biologically active natural products often contain particularly challenging structural features and functionalities in terms of synthesis. Perhaps the greatest difficulties are those caused by issues of stereochemistry. A useful strategy for synthesizing such molecules is to devise methods of bond formation that provide opportunities for using enantioselective catalysis. In using this tactic, the desire for a particular target structure ultimately drives the development of catalytic methods. New enantioselective catalytic methods contribute to a greater fundamental understanding of how bonds can be constructed and lead to valuable synthetic technologies that are useful for a variety of applications.

The catalytic stereoselective synthesis of compounds with chiral phosphorus centers remains an unsolved problem. State-of-the-art methods rely on resolution or stoichiometric chiral auxiliaries. Phosphoramidate prodrugs are a critical component of pronucleotide (ProTide) therapies used in the treatment of viral disease and cancer. Here we describe the development of a catalytic stereoselective method for the installation of phosphorus-stereogenic phosphoramidates to nucleosides through a dynamic stereoselective process. Detailed mechanistic studies and computational modeling led to the rational design of a multifunctional catalyst that enables stereoselectivity as high as 99:1.

Efficient catalytic reactions that can generate C–C bonds enantioselectively, and ones that can produce trisubstituted alkenes diastereoselectively, are central to research in organic chemistry. Transformations that accomplish these two tasks simultaneously are in high demand, particularly if the catalysts, substrates and reagents are inexpensive and if the reaction conditions are mild. Here we report a facile multicomponent catalytic process that begins with a chemoselective, site-selective and diastereoselective copper–boron addition to a monosubstituted allene; the resulting boron-substituted organocopper intermediates then participate in a similarly selective allylic substitution. The products, which contain a stereogenic carbon centre, a monosubstituted alkene and an easily functionalizable Z -trisubstituted alkenylboron group, are obtained in up to 89 per cent yield, with more than 98 per cent branch-selectivity and stereoselectivity and an enantiomeric ratio greater than 99:1. The copper-based catalyst is derived from a robust heterocyclic salt that can be prepared in multigram quantities from inexpensive starting materials and without costly purification procedures. The utility of the approach is demonstrated through enantioselective synthesis of gram quantities of two natural products, namely rottnestol and herboxidiene (also known as GEX1A). A catalytic process is reported that begins with a highly selective copper–boron addition to a monosubstituted allene, and in which the resulting boron-substituted organocopper intermediate then participates in a chemoselective, site-selective and enantioselective allylic substitution; this approach is used in the enantioselective synthesis of gram quantities of two natural products. A new route to organoboron compounds This paper reports a catalytic process that combines two simple unsaturated organic molecules — a highly selective copper–diboron reagent and a monosubstituted allene — to produce a boron-substituted organocopper intermediate that then participates in a chemoselective, site-selective and enantioselective allylic substitution. The authors use this approach in the enantioselective synthesis of gram quantities of two natural products: the anti-tumour agent herboxidiene and stereoisomerically pure rottnestol, a hemiketal originally isolated from a marine sponge. Further development of this procedure should lead to economical protocols for the synthesis of other difficult-to-access alkenylboron-containing organocopper compounds.

The manipulation of traditionally unreactive functional groups is of paramount importance in modern chemical synthesis. We have developed an iron-dipyrrinato catalyst that leverages the reactivity of iron-borne metal-ligand multiple bonds to promote the direct amination of aliphatic C-H bonds. Exposure of organic azides to the iron dipyrrinato catalyst furnishes saturated, cyclic amine products (N-heterocycles) bearing complex core-substitution patterns. This study highlights the development of C-H bond functionalization chemistry for the formation of saturated, cyclic amine products and should find broad application in the context of both Pharmaceuticals and natural product synthesis.

Many features of extracellular matrices, e.g., self-healing, adhesiveness, viscoelasticity, and conductivity, are associated with the intricate networks composed of many different covalent and non-covalent chemical bonds. Whereas a reductionism approach would have the limitation to fully recapitulate various biological properties with simple chemical structures, mimicking such sophisticated networks by incorporating many different functional groups in a macromolecular system is synthetically challenging. Herein, we propose a strategy of convergent synthesis of complex polymer networks to produce biomimetic electroconductive liquid metal hydrogels. Four precursors could be individually synthesized in one to two reaction steps and characterized, then assembled to form hydrogel adhesives. The convergent synthesis allows us to combine materials of different natures to generate matrices with high adhesive strength, enhanced electroconductivity, good cytocompatibility in vitro and high biocompatibility in vivo. The reversible networks exhibit self-healing and shear-thinning properties, thus allowing for 3D printing and minimally invasive injection for in vivo experiments. The need for multifunctional materials for tissue engineering applications requires the development of multicomponent systems. Here, the authors report on the creation of a liquid metal-containing hydrogel with multiple covalent and noncovalent bonds to produce a tailorable, biocompatible biomaterial.