Navigating and expanding the roadmap of natural product genome mining tools

• Friederike Biermann,
• Sebastian L. Wenski and
• Eric J. N. Helfrich

Beilstein J. Org. Chem. 2022, 18, 1656–1671, doi:10.3762/bjoc.18.178

• yellow, genes in green and motifs in violet. Concepts of algorithms in order of complexity and examples of genome mining tools that employ the respective concept. Examples of peptide NPs, the corresponding BGCs of which were determined through retrobiosynthetic analysis and then experimentally verified

Oxa-Michael-initiated cascade reactions of levoglucosenone

• Julian Klepp,
• Thomas Bousfield,
• Hugh Cummins,
• Sarah V. A.-M. Legendre,
• Jason E. Camp and
• Ben W. Greatrex

Beilstein J. Org. Chem. 2022, 18, 1457–1462, doi:10.3762/bjoc.18.151

• 5.14 ppm, CDCl3) [22]. Other hemiketal type structures may be responsible for some of the complexity as the reaction progresses, as this addition is common to the 6,8-dioxabicyclo[3.2.1]octan-4-one ring system. It is interesting that even with equimolar benzaldehyde and 1, the 2:1 bridged species 5a

B–N/B–H Transborylation: borane-catalysed nitrile hydroboration

• Filip Meger,
• Alexander C. W. Kwok,
• Franziska Gilch,
• Dominic R. Willcox,
• Alex J. Hendy,
• Kieran Nicholson,
• Andrew D. Bage,
• Thomas Langer,
• Thomas A. Hunt and
• Stephen P. Thomas

Beilstein J. Org. Chem. 2022, 18, 1332–1337, doi:10.3762/bjoc.18.138

• comparable activity to H3B·SMe2 (Scheme 3b) and the reduced number of reactive B–H sites to reduce complexity. Following hydroboration of the nitrile by H-B-9-BBN to give the N-B-9-BBN imine 6, the reaction can proceed by two routes to give the N,N-bis-Bpin amine 4a: A) a second hydroboration by H-B-9-BBN to

Cytochrome P450 monooxygenase-mediated tailoring of triterpenoids and steroids in plants

• Karan Malhotra and
• Jakob Franke

Beilstein J. Org. Chem. 2022, 18, 1289–1310, doi:10.3762/bjoc.18.135

• formation in the product melianol (21). It is believed that these transformations are the starting point for formation of the characteristic furan ring of limonoids [29]. Taken together, these case studies not only represent impressive examples how CYPs create chemical complexity in plant triterpenoid and

A Streptomyces P450 enzyme dimerizes isoflavones from plants

• Run-Zhou Liu,
• Shanchong Chen and
• Lihan Zhang

Beilstein J. Org. Chem. 2022, 18, 1107–1115, doi:10.3762/bjoc.18.113

• seen in vinblastine [2], julichrome [3], himastatin [4], and biflavone [5]. However, the structural complexity of the dimeric natural products has hampered synthetic chemistry approaches towards these molecules, since chemo-, regio-, and atroposelective formation of the biaryl linkage remains highly

Morita–Baylis–Hillman reaction of 3-formyl-9H-pyrido[3,4-b]indoles and fluorescence studies of the products

• Nisha Devi and
• Virender Singh

Beilstein J. Org. Chem. 2022, 18, 926–934, doi:10.3762/bjoc.18.92

• leading to the formation of allylic alcohol; a highly functionalized product [41][42][43][44]. The chemistry of the MBH reaction is decorated with several unique features viz. atom economy, complexity generation and generation of a chiral center from a pro-chiral electrophile. The chemistry of the MBH

Efficient production of clerodane and ent-kaurane diterpenes through truncated artificial pathways in Escherichia coli

• Fang-Ru Li,
• Xiaoxu Lin,
• Qian Yang,
• Ning-Hua Tan and
• Liao-Bin Dong

Beilstein J. Org. Chem. 2022, 18, 881–888, doi:10.3762/bjoc.18.89

• complexity [12]. Additionally, chemical transformations from commercial natural products are also tedious and currently limited to a few diterpene skeletons [8]. Engineering microbes via synthetic biology provides new opportunities to produce terpenoid carbon skeletons. All terpenoids are derived from the

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

Asymmetric organocatalytic Michael addition of cyclopentane-1,2-dione to alkylidene oxindole

• Estelle Silm,
• Ivar Järving and
• Tõnis Kanger

Beilstein J. Org. Chem. 2022, 18, 167–173, doi:10.3762/bjoc.18.18

• molecular complexity. There are many examples of the organocatalytic synthesis of fused cycles starting from the cyclohexane-1,3-dione. For example, Rueping et al. demonstrated that the cyclohexane-1,3-dione undergoes a cascade reaction with α,β-unsaturated aldehydes [4] and they later employed the method

Mechanistic studies of the solvolysis of alkanesulfonyl and arenesulfonyl halides

• Malcolm J. D’Souza and
• Dennis N. Kevill

Beilstein J. Org. Chem. 2022, 18, 120–132, doi:10.3762/bjoc.18.13

• . However, what Hammett pointed out [79] several years ago is still relevant today. The section of the “Solvolysis Revisited” review [31] dealing with kinetic solvent isotope effects (pages 168–169) illustrates the extreme complexity of this topic and the uncertainty as to the extents to which the ksie

1,2-Naphthoquinone-4-sulfonic acid salts in organic synthesis

• Ruan Carlos B. Ribeiro,
• Patricia G. Ferreira,
• Amanda de A. Borges,
• Luana da S. M. Forezi,
• Fernando de Carvalho da Silva and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 53–69, doi:10.3762/bjoc.18.5

• , a mixture of products is formed, among which 22 and 23 are the majority. It is important to note that the complexity of the reaction of β-NQS with primary aliphatic amines has already been reported in the literature. Fieser and Fieser [71] studied the reduction potentials of various naphthoquinones

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

Selective sulfonylation and isonitrilation of para-quinone methides employing TosMIC as a source of sulfonyl group or isonitrile group

• Chuanhua Qu,
• Run Huang,
• Yong Li,
• Tong Liu,
• Yuan Chen and
• Guiting Song

Beilstein J. Org. Chem. 2021, 17, 2822–2831, doi:10.3762/bjoc.17.193

• preparation of highly valuable diarylmethyl sulfones are relatively scarce [24]. In addition, the important link between structural diversity and complexity with bioactivity represented by sulfones has led to the goal of developing strategies to as many these pivotal scaffolds as possible. Isocyanide is an

A visible-light-induced, metal-free bis-arylation of 2,5-dichlorobenzoquinone

• Pieterjan Winant and
• Wim Dehaen

Beilstein J. Org. Chem. 2021, 17, 2315–2320, doi:10.3762/bjoc.17.149

• consisting of a mixture of mono- and bis-arylated products, accompanied by a range of unwanted side products. The complexity of the mixture resulted in the isolation of compound 3a in a rather poor yield of 15% (Table 1, entry 1). Furthermore, this initial experiment elucidated that four equivalents (two per

Post-functionalization of drug-loaded nanoparticles prepared by polymerization-induced self-assembly (PISA) with mitochondria targeting ligands

• Janina-Miriam Noy,
• Fan Chen and
• Martina Stenzel

Beilstein J. Org. Chem. 2021, 17, 2302–2314, doi:10.3762/bjoc.17.148

• outcomes, illustrating the complexity in understanding and designing efficient drug-delivery systems in biological environments. It needs to be considered that TPP, despite its positive charge, still carries large phenyl groups that render the surface hydrophobic. While this can affect protein adsorption

Halides as versatile anions in asymmetric anion-binding organocatalysis

• Lukas Schifferer,
• Martin Stinglhamer,
• Kirandeep Kaur and
• Olga García Macheño

Beilstein J. Org. Chem. 2021, 17, 2270–2286, doi:10.3762/bjoc.17.145

• targeting of the small receptor molecule and, thus, reducing the need for complexity compared to enzymes or co-factors. Conversely, a multitude of geometries may need to be considered for anions with linear, coplanar, trigonal or tetrahedral topologies (Figure 1b) [5][10]. However, following the advances in

• halide anions can also engage as the nucleophile, which has been exploited in ring opening and related reactions (Figure 3b). In general, the idea of enantioselective ring opening produces two fixed stereocenters during one synthetic operation, increasing the complexity of the product significantly. This

Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

Enantioenriched α-substituted glutamates/pyroglutamates via enantioselective cyclopropenimine-catalyzed Michael addition of amino ester imines

• Zara M. Seibel,
• Jeffrey S. Bandar and
• Tristan H. Lambert

Beilstein J. Org. Chem. 2021, 17, 2077–2084, doi:10.3762/bjoc.17.134

• organizational interactions. This complexity makes the detailed prediction of the transition state organization for the current process very challenging. However, we propose that the general structure 19 shown in Figure 3 is a reasonable representation of one of the likely pathways (the major ambiguities being

Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

• ]. Nevertheless, the complexity and diversity of polysaccharides makes synthetic processes extremely laborious and time consuming. Several aspects are crucial to plan a successful polysaccharide synthesis. Properly designed starting materials and/or catalysts are required to ensure regio- and stereocontrol during

• suggested that XGs are not essential for the creation of the cellulose network [96]. The complexity and diversity of XGs hinder isolation from natural sources and complicates their description. A significant effort was put towards the development of enzymes for selective introduction of the side chains [97

• introduce the fucose residues [110]. Even though the complexity of plant polysaccharides hinders their synthesis, these compounds are highly desirable to dissect the different interactions taking place in the plant cell-wall. Recognition of the branched oligomers by glycosynthases proved to be limited and

Asymmetric organocatalyzed synthesis of coumarin derivatives

• Natália M. Moreira,
• Lorena S. R. Martelli and
• Arlene G. Corrêa

Beilstein J. Org. Chem. 2021, 17, 1952–1980, doi:10.3762/bjoc.17.128

• -catalyzed cross-coupling reactions of coumarin derivatives [24]. Coumarins are a promising scaffold for design and development of bioactive agents, however it possesses a flat system [25]. One of the attractive benefits of introducing chirality in a drug candidate is that it leads to increased complexity to

Natural products in the predatory defence of the filamentous fungal pathogen Aspergillus fumigatus

• Jana M. Boysen,
• Nauman Saeed and
• Falk Hillmann

Beilstein J. Org. Chem. 2021, 17, 1814–1827, doi:10.3762/bjoc.17.124

• environmental niches remained elusive and has been limited by their biological complexity. It was thus surprising to find that the environmentally abundant, fungivorous amoeba P. aurantium does not only graze on yeast but can specifically target filamentous fungi such as A. fumigatus. The mechanism of action

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

• barrier crossing of PNAs by intravenous administration of PNA conjugated to OX26 murine monoclonal antibody to the rat transferrin receptor [165]. The limitation of this strategy was complexity of the construct and lack of clear evidence for the cellular uptake. The first report of using the PNA–peptide

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• reactions an ideal platform for the synthesis of molecules with increased molecular complexity. Keywords: hydroalkylation; hydrogen atom transfer; quaternary carbon center; radical addition; unactivated olefins; Introduction Natural product structures remain some of the main sources of inspiration for the

• synthesis of new bioactive compounds [1][2]. A careful view of the carbon backbone of these natural molecules reveals their high molecular complexity [3][4][5], which can be described by the presence of multiple stereogenic centers in the same molecule, a substantial fraction of sp3 hybridized carbons (Fsp3

• molecular complexity of drugs in drug discovery programs, aiming at molecules with better selectivity for biological targets [6][15][16]. One ideal way to achieve more complex molecular architectures is by hydroalkylation of olefins, a reaction that forms new C(sp3)–C(sp3) and C(sp3)–H bonds at the expense

Chemical synthesis of C6-tetrazole ᴅ-mannose building blocks and access to a bioisostere of mannuronic acid 1-phosphate

• Eleni Dimitriou and
• Gavin J. Miller

Beilstein J. Org. Chem. 2021, 17, 1527–1532, doi:10.3762/bjoc.17.110

• separable regioisomers and their structures were confirmed by HMBC, as previously demonstrated. Removal of the need to orthogonally protect C4 expectedly reduced the complexity of the synthetic route and nine steps for the synthesis of donors of type 11/12 was reduced to five steps for 18/19. Moreover, the

Total synthesis of ent-pavettamine

• Memory Zimuwandeyi,
• Manuel A. Fernandes,
• Amanda L. Rousseau and
• Moira L. Bode

Beilstein J. Org. Chem. 2021, 17, 1440–1446, doi:10.3762/bjoc.17.99

• steps. As before, (S)-malic acid (3) was chosen as the starting material because its inherent chirality reduced the complexity of the synthetic process. Given the fact that the target molecule has C2 symmetry, it was prudent that a synthetic route starting from a common C5 subunit be chosen, with