The (±)-5-Aza[1.0]triblattane Skeleton via Azetine Cycloaddition

The first synthesis of the 5-aza[1.0]triblattane skeleton was achieved through a [4 + 2] cycloaddition approach using a suitably protected azetine and cyclopentadiene. A series of azetines were synthesized to explore both stability and suitable N-protection. The key step following cycloaddition utilized a noninitiated protonated aminyl radical cyclization to install the final 5-azatriblattane bond, but it was found to be considerably more unstable than the 6-aza isomer under acidic conditions.

1,3-Disubstituted-1,2,4-triazin-6-ones with potent activity against androgen receptor-dependent prostate cancer cells

Synthesis and biological evaluation of a small, focused library of 1,3-disubstituted-1,2,4-triazin-6-ones for in vitro inhibitory activity against androgen-receptor-dependent (22Rv1) and androgen-receptor independent (PC3) castration-resistant prostate cancer (CRPC) cells led to highly active compounds with in vitro IC50 values against 22Rv1 cells of <200 nM, and with apparent selectivity for this cell type over PC3 cells. From metabolic/PK evaluations of these compounds, a 3-benzyl-1-(2,4-dichlorobenzyl) derivative had superior properties and showed considerably stronger activity, by nearly an order of magnitude, against AR-dependent LNCaP and C4-2B cells compared to AR-independent DU145 cells. This lead compound decreased AR expression in a dose and time dependent manner and displayed promising therapeutic effects in a 22Rv1 CRPC xenograft mouse model. Computational target prediction and subsequent docking studies suggested three potential known prostate cancer targets: p38a MAPK, TGF-β1, and HGFR/c-Met, with the latter case of c-Met appearing stronger, owing to close structural similarity of the lead compound to known pyridazin-3-one derivatives with potent c-Met inhibitory activity. RNA-seq analysis showed dramatic reduction of AR signalling pathway and/or target genes by the lead compound, subsequently confirmed by quantitative PCR analysis. The lead compound was highly inhibitory against HGF, the c-Met ligand, which fitted well with the computational target prediction and docking studies. These results suggest that this compound could be a promising starting point for the development of an effective therapy for the treatment of CRPC.

9-Azahomocubane

Homocubane, a highly strained cage hydrocarbon, contains two very different positions for the introduction of a nitrogen atom into the skeleton, e. g., a position 1 exchange results in a tertiary amine whereas position 9 yields a secondary amine. Herein reported is the synthesis of 9-azahomocubane along with associated structural characterization, physical property analysis and chemical reactivity. Not only is 9-azahomocubane readily synthesized, and found to be stable as predicted, the basicity of the secondary amine was observed to be significantly lower than the structurally related azabicyclo[2.2.1]heptane, although similar to 1-azahomocubane.

seco-1-Azacubane-2-carboxylic Acid: Derivative Scope and Comparative Biological Evaluation

The unusual and sterically constrained amino acid, seco-1-azacubane-2-carboxylic acid, was incorporated into a range of bioactive chemical templates, including enalaprilat, perindoprilat, endomorphin-2 and isoniazid, and subjected to biological testing. The endomorphin-2 derivative displayed increased activity at the δ opioid receptor, but a loss in activity was observed in the other cases, although human normal cell line evaluation suggests limited cytotoxic effects.

Interrogating Aptamer Chemical Space Through Modified Nucleotide Substitution Facilitated by Enzymatic DNA Synthesis

Chemical modification of aptamers is an important step to improve their performance and stability in biological media. This can be performed either during their identification (mod-SELEX) or after the in vitro selection process (post-SELEX). In order to reduce the complexity and workload of the post-SELEX modification of aptamers, we have evaluated the possibility of improving a previously reported, chemically modified aptamer by combining enzymatic synthesis and nucleotides bearing bioisosteres of the parent cubane side-chains or substituted cubane moieties. This method lowers the synthetic burden often associated with post-SELEX approaches and allowed to identify one additional sequence that maintains binding to the PvLDH target protein, albeit with reduced specificity. In addition, while bioisosteres often improve the potency of small molecule drugs, this does not extend to chemically modified aptamers. Overall, this versatile method can be applied for the post-SELEX modification of other aptamers and functional nucleic acids.

seco-1-Azacubane-2-carboxylic acid-Amide Bond Comparison to Proline

seco-1-Azacubane-2-carboxylic acid, an unusual and sterically constrained amino acid, was found to undergo amide bond formation at both the N- and C-termini using proline based bioactive molecule templates as a concept platform.

1-Azahomocubane

Highly strained cage hydrocarbons have long stood as fundamental molecules to explore the limits of chemical stability and reactivity, probe physical properties, and more recently as bioactive molecules and in materials discovery. Interestingly, the nitrogenous congeners have attracted much less attention. Previously absent from the literature, azahomocubanes, offer an opportunity to investigate the effects of a nitrogen atom when incorporated into a highly constrained polycyclic environment. Herein disclosed is the synthesis of 1-azahomocubane, accompanied by comprehensive structural characterization, physical property analysis and chemical reactivity. These data support the conclusion that nitrogen is remarkably well tolerated in a highly strained environment.

1-Benzyloxy-5-phenyltetrazole derivatives highly active against androgen receptor-dependent prostate cancer cells

A series of 1-benzyloxy-5-phenyltetrazole derivatives and similar compounds were synthesized and evaluated for their in vitro inhibitory activity against androgen-receptor-dependent (22Rv1) and androgen-receptor independent (PC3) prostate cancer cells. The most active compounds had in vitro IC₅₀ values against 22Rv1 cells of <50 nM and showed apparent selectivity for this cell type over PC3 cells; however, these active compounds had short half-lives when incubated with mouse liver microsomes and/or when plasma concentration was monitored during in vivo pharmacokinetic studies in mice or rats. Importantly, lead compound 1 exhibited promising inhibitory effects on cell proliferation, expression of AR and its splicing variant AR-v7 as well as AR regulated target genes in 22Rv1 cells, which are so called castration-resistant prostate cancer (CRPC) cells, and a 22Rv1 CRPC xenograft tumour model in mice. Structural changes which omitted the N-O-benzyl moiety led to dramatic or total loss of activity and S-benzylation of a cysteine derivative, as a surrogate for in vivo S-nucleophiles, by representative highly active compounds, suggested a possible chemical reactivity basis for this "activity cliff" and poor pharmacokinetic profile. However, representative highly active compounds did not inhibit a cysteine protease, indicating that the mode of activity is unlikely to be protein modification by S-benzylation. Despite our efforts to elucidate the mode of action, the mechanism remains unclear.

The (±)-6-Aza[1.0]triblattane Skeleton: Contraction beyond the Wilder-Culberson Ring System

Synthesis of the 6-aza[1.0]triblattane skeleton and the unexpected construction of the 7-azatetracyclo[4.2.1.0^2,5.0^3,7]nonane framework are reported, as inspired by the Wilder-Culberson 1-aza[1.1]triblattane ring system. The key steps to assess the 6-aza[1.0]triblattane include accessing the 1,6-cycloaddition product from reaction of chlorosulfonyl isocyanate with cyclohept-1,3,5-triene followed by intramolecular electrocyclization and aminium radical cyclization.

A novel vitamin K derived anticoagulant tolerant to genetic variations of vitamin K epoxide reductase

BACKGROUND

Vitamin K antagonists (VKAs), such as warfarin, have remained the cornerstone of oral anticoagulation therapy in the prevention and treatment of thromboembolism for more than half a century. They function by impairing the biosynthesis of vitamin K-dependent (VKD) clotting factors through the inhibition of vitamin K epoxide reductase (VKOR). The challenge of VKAs therapy is their narrow therapeutic index and highly variable dosing requirements, which are partially the result of genetic variations of VKOR.

OBJECTIVES

The goal of this study was to search for an improved VKA that is tolerant to the genetic variations of its target enzyme.

METHODS

A series of vitamin K derivatives with benzyl and related side-chain substitutions at the 3-position of 1,4-naphthoquinone were synthesized. The role of these compounds in VKD carboxylation was evaluated by mammalian cell-based assays and conventional in vitro activity assays.

RESULTS

Our results showed that replacing the phytyl side-chain with a methylene cyclooctatetraene (COT) moiety at the 3-position of vitamin K1 converted it from a substrate to an inhibitor for VKD carboxylation. Strikingly, this COT-vitamin K derivative displayed a similar inhibition potency in warfarin-resistant VKOR mutations whose warfarin resistance varied more than 400-fold. Further characterization of COT-vitamin K for the inhibition of VKD carboxylation suggested that this compound targets multiple enzymes in the vitamin K redox cycle. Importantly, the anticoagulation effect of COT-vitamin K can be rescued with high doses of vitamin K1 .

CONCLUSION

We discovered a vitamin K analogue that functions as a VKA and is tolerant to genetic variations in the target enzyme.

Enone-promoted decarboxylation of trans-4-hydroxy-l-proline in flow: a side-by-side comparison to batch

An efficient and scalable enone-promoted method for the decarboxylation of trans-4-hydroxy-proline has been developed in flow to provide access to (R)-pyrrolidin-3-ol hydrochloride using biomass-derived isophorone.

Nonclassical Phenyl Bioisosteres as Effective Replacements in a Series of Novel Open-Source Antimalarials

The replacement of one chemical motif with another that is broadly similar is a common method in medicinal chemistry to modulate the physical and biological properties of a molecule (i.e., bioisosterism). In recent years, bioisosteres such as cubane and bicyclo[1.1.1]pentane (BCP) have been used as highly effective phenyl mimics. Herein, we show the successful incorporation of a range of phenyl bioisosteres during the open-source optimization of an antimalarial series. Cubane (19) and closo-carborane (23) analogues exhibited improved in vitro potency against Plasmodium falciparum compared to the parent phenyl compound; however, these changes resulted in a reduction in metabolic stability; unusually, enzyme-mediated oxidation was found to take place on the cubane core. A BCP analogue (22) was found to be equipotent to its parent phenyl compound and showed significantly improved metabolic properties. While these results demonstrate the utility of these atypical bioisosteres when used in a medicinal chemistry program, the search to find a suitable bioisostere may well require the preparation of many candidates, in our case, 32 compounds.

Relay Cross Metathesis for the Iterative Construction of Terpenoids and Synthesis of a Diterpene-Benzoate Macrolide of Biogenetic Relevance to the Bromophycolides

We report a relay cross metathesis (ReXM) reaction for the construction of terpenoids in an iterative protocol. The protocol features the cross metathesis of a relay-actuated Δ^6,7-functionalized C₁₀-monoterpenoid alcohol with C₁₀-monoterpenoid citral to form a C₁₅-sesquiterpene. Subsequent functional group manipulation allows for the method to be repeated in an iterative fashion. The method is used for the synthesis of a diterpene-benzoate macrolide of biogenetic relevance to the bromophycolide family of natural products.

A Relay Strategy Actuates Pre-Existing Trisubstituted Olefins in Monoterpenoids for Cross-Metathesis with Trisubstituted Alkenes

A retrosynthetic disconnection-reconnection analysis of epoxypolyenes-substrates that can undergo cyclization to podocarpane-type tricycles-reveals relay-actuated Δ^6,7-functionalized monoterpenoid alcohols for ruthenium benzylidene catalyzed olefin cross-metathesis with homoprenyl benzenes. Successful implementation of this approach provided several epoxypolyenes as expected (E/Z, ca. 2-3:1). The method is further generalized for the cross-metathesis of pre-existing trisubstituted olefins in other relay-actuated Δ^6,7-functionalized monoterpenoid alcohols with various other trisubstituted alkenes to form new trisubstituted olefins. Epoxypolyene cyclization of an enantiomerically pure, but geometrically impure, epoxypolyene substrate provides an enantiomerically pure, trans-fused, podocarpane-type tricycle (from the E-geometrical isomer).

The cubane paradigm in bioactive molecule discovery: further scope, limitations and the cyclooctatetraene complement

The cubane phenyl ring bioisostere paradigm was further explored in an extensive study covering a wide range of pharmaceutical and agrochemical templates, which included antibiotics (cefaclor, penicillin G) and antihistamine (diphenhydramine), a smooth muscle relaxant (alverine), an anaesthetic (ketamine), an agrochemical instecticide (triflumuron), an antiparasitic (benznidazole) and an anticancer agent (tamibarotene). This investigation highlights the scope and limitations of incorporating cubane into bioactive molecule discovery, both in terms of synthetic compatibility and physical property matching. Cubane maintained bioisosterism in the case of the Chagas disease antiparasitic benznidazole, although it was less active in the case of the anticancer agent (tamibarotenne). Application of the cyclooctatetraene (COT) (bio)motif complement was found to optimize benznidazole relative to the benzene parent, and augmented anticancer activity relative to the cubane analogue in the case of tamibarotene. Like all bioisosteres, scaffolds and biomotifs, however, there are limitations (e.g. synthetic implementation), and these have been specifically highlighted herein using failed examples. A summary of all templates prepared to date by our group that were biologically evaluated strongly supports the concept that cubane is a valuable tool in bioactive molecule discovery and COT is a viable complement.

Cyclooctatetraene: A Bioactive Cubane Paradigm Complement

Cubane was recently validated as a phenyl ring (bio)isostere, but highly strained caged carbocyclic systems lack π character, which is often critical for mediating key biological interactions. This electronic property restriction associated with cubane has been addressed herein with cyclooctatetraene (COT), using known pharmaceutical and agrochemical compounds as templates. COT either outperformed or matched cubane in multiple cases suggesting that versatile complementarity exists between the two systems for enhanced bioactive molecule discovery.

Enantioselective synthesis of (R)-2-cubylglycine including unprecedented rhodium mediated C–H insertion of cubane

An enantioselective synthesis of the non-proteinogenic amino acid (R)-2-cubylglycine and the first examples of cubane C–H insertion are reported.

A Scalable, Combined-Batch, and Continuous-Flow Synthesis of a Bio-Inspired UV-B Absorber

A new, chromatography-free synthesis for the preparation of an experimental UV-B absorber is reported. A key step of the process is a one-pot partial reduction of a symmetrical imide with a sequential dehydration step. The synthesis uses several continuous-flow steps to increase sample throughput and was used to prepare sufficient material to support further testing activities in &gt;99% purity.

Synthesis of the seco-Limonoid BCD Ring System Identifies a Hsp90 Chaperon Machinery (p23) Inhibitor

D-Ring-seco-limonoids (tetranortriterpenoids), such as gedunin and xylogranin B display anti-cancer activity, acting via inhibition of Hsp90 and/or associated chaperon machinery (e.g., p23). Despite this, these natural products have received relatively little attention, both in terms of an enabling synthetic approach (which would allow access to derivatives), and as a consequence their structure-activity relationship (SAR). Disclosed herein is a generally applicable synthetic route to the BCD ring system of the seco-D-ring double bond containing limonoids. Furthermore, cell based assays revealed the first skeletal fragment that exhibited inhibition of the p23 enzyme at a level which was equipotent to that of gedunin, despite being much less structurally complex.

Kinetic Benchmarking Reveals the Competence of Prenyl Groups in Ring-Closing Metathesis

A series of prenyl-containing malonates are kinetically benchmarked against the standard allyl-containing congeners using a ruthenium benzylidene precatalyst for ring-closing metatheses. The prenyl grouping is found to be a superior acceptor olefin compared to an allyl group in RCM processes with ruthenium alkylidenes derived from terminal alkenes. The prenyl group is also found to be a highly competent acceptor for a ruthenium alkylidene derived from a 1,1-disubstituted olefin in a RCM process.

Validating Eaton's Hypothesis: Cubane as a Benzene Bioisostere

Pharmaceutical and agrochemical discovery programs are under considerable pressure to meet increasing global demand and thus require constant innovation. Classical hydrocarbon scaffolds have long assisted in bringing new molecules to the market place, but an obvious omission is that of the Platonic solid cubane. Eaton, however, suggested that this molecule has the potential to act as a benzene bioisostere. Herein, we report the validation of Eaton's hypothesis with cubane derivatives of five molecules that are used clinically or as agrochemicals. Two cubane analogues showed increased bioactivity compared to their benzene counterparts whereas two further analogues displayed equal bioactivity, and the fifth one demonstrated only partial efficacy. Ramifications from this study are best realized by reflecting on the number of bioactive molecules that contain a benzene ring. Substitution with the cubane scaffold where possible could revitalize these systems, and thus expedite much needed lead candidate identification.

Unexpected Isomerisation of a Fragment Analogue During Fragment-Based Screening of HIV Integrase Catalytic Core Domain

Fragment-based screening of human immunodeficiency virus type 1 (HIV) integrase revealed several aromatic carboxylic acid fragment hits, some of which bound weakly at the site on the HIV-integrase catalytic core domain that binds the lens epithelium-derived growth factor (LEDGF). Virtual screening of an internal database identified an analogue that bound with higher affinity and in an isomerised form to the LEDGF binding site. The starting lactone was stable in CDCl3; however, an unexpected isomerisation process occurred in [D6]DMSO to give the same isomer found in the LEDGF binding site. This hit led directly to a series of low-micromolar LEDGF inhibitors and, via a scaffold hop, to a series of allosteric binding site inhibitors.

The direct α-C(sp3)–H functionalisation of N-aryl tetrahydroisoquinolines via an iron-catalysed aerobic nitro-Mannich reaction and continuous flow processing

An efficient nitro-Mannich type direct α-C(sp³)–H functionalisation of N-aryl-1,2,3,4-tetrahydroisoquinolines catalysed by simple iron salts in combination with O₂ as the terminal oxidant is described.

Porous double-layer polymer tubing for the potential use in heterogeneous continuous flow reactions

Functional polymer tubing with an OD of 1/16 or 1/8 in. was fabricated by a simple polymer coextrusion process. The tubing was made of an outer impervious polypropylene layer and an inner layer, consisting of a blend of a functional polymer, polyethylene-co-methacrylic acid, and a sacrificial polymer, polystyrene. After a simple solvent leaching step using common organic solvents, the polystyrene was removed, leaving behind a porous inner layer that contains functional carboxylic acid groups, which could then be used for the immobilization of target molecules. Solution-phase reactions using amines or isocyanates have proven successful for the immobilization of a series of small molecules and polymers. This flexible multilayered functional tubing can be easily cut to the desired length and connected via standard microfluidic fittings.

Design, synthesis and binding properties of a fluorescent α₉β₁/α₄β₁ integrin antagonist and its application as an in vivo probe for bone marrow haemopoietic stem cells

The α9β1 and α4β1 integrin subtypes are expressed on bone marrow haemopoietic stem cells and have important roles in stem cell regulation and trafficking. Although the roles of α4β1 integrin have been thoroughly investigated with respect to HSC function, the role of α9β1 integrin remains poorly characterised. Small molecule fluorescent probes are useful tools for monitoring biological processes in vivo, to determine cell-associated protein localisation and activation, and to elucidate the mechanism of small molecule mediated protein interactions. Herein, we report the design, synthesis and integrin-dependent cell binding properties of a new fluorescent α9β1 integrin antagonist (R-BC154), which was based on a series of N-phenylsulfonyl proline dipeptides and assembled using the Cu(I)-catalyzed azide alkyne cycloaddition (CuAAC) reaction. Using transfected human glioblastoma LN18 cells, we show that R-BC154 exhibits high nanomolar binding affinities to α9β1 integrin with potent cross-reactivity against α4β1 integrin under physiological mimicking conditions. On-rate and off-rate measurements revealed distinct differences in the binding kinetics between α9β1 and α4β1 integrins, which showed faster binding to α4β1 integrin relative to α9β1, but more prolonged binding to the latter. Finally, we show that R-BC154 was capable of binding rare populations of bone marrow haemopoietic stem and progenitor cells when administered to mice. Thus, R-BC154 represents a useful multi-purpose fluorescent integrin probe that can be used for (1) screening small molecule inhibitors of α9β1 and α4β1 integrins; (2) investigating the biochemical properties of α9β1 and α4β1 integrin binding and (3) investigating integrin expression and activation on defined cell phenotypes in vivo.

The search for new amphiphiles: synthesis of a modular, high-throughput library

Amphiphilic compounds are used in a variety of applications due to their lyotropic liquid-crystalline phase formation, however only a limited number of compounds, in a potentially limitless field, are currently in use. A library of organic amphiphilic compounds was synthesised consisting of glucose, galactose, lactose, xylose and mannose head groups and double and triple-chain hydrophobic tails. A modular, high-throughput approach was developed, whereby head and tail components were conjugated using the copper-catalysed azide-alkyne cycloaddition (CuAAC) reaction. The tails were synthesised from two core alkyne-tethered intermediates, which were subsequently functionalised with hydrocarbon chains varying in length and degree of unsaturation and branching, while the five sugar head groups were selected with ranging substitution patterns and anomeric linkages. A library of 80 amphiphiles was subsequently produced, using a 24-vial array, with the majority formed in very good to excellent yields. A preliminary assessment of the liquid-crystalline phase behaviour is also presented.

Oxalate content of foods and its effect on humans

Oxalic acid and its salts occur as end products of metabolism in a number of plant tissues. When these plants are eaten they may have an adverse effect because oxalates bind calcium and other minerals. While oxalic acid is a normal end product of mammalian metabolism, the consumption of additional oxalic acid may cause stone formation in the urinary tract when the acid is excreted in the urine. Soaking and cooking of foodstuffs high in oxalate will reduce the oxalate content by leaching. The mean daily intake of oxalate in English diets has been calculated to be 70-150 mg, with tea appearing to contribute the greatest proportion of oxalate in these diets; rhubarb, spinach and beet are other common high oxalate-content foods. Vegetarians who consume greater amounts of vegetables will have a higher intake of oxalates, which may reduce calcium availability. This may be an increased risk factor for women, who require greater amounts of calcium in the diet. In humans, diets low in calcium and high in oxalates are not recommended but the occasional consumption of high oxalate foods as part of a nuritious diet does not pose any particular problem.

What's in a Name? Moving Towards a Limited Vocabulary for Macromolecular Crystallisation

This paper discusses the need for a systematic and standard naming nomenclature within the field of macromolecular crystallisation, and presents a set of rules and standard names which provides a start towards this end. The field of protein crystallisation is populated by biologists and chemists, and the dictionary in use needs to be unambiguous to both disciplines, yet must have useability as the most fundamental tenet if it is going to be widely adopted.

Benzonitrile Oxide Cycloadditions with Exocyclic Methylene Benzothiazepine Dioxides

N-substituted 5-methylene-2,3,4,5-tetrahydrobenzo[f][1,2]thiazepine 1,1-dioxides underwent 1,3-dipolar cycloaddition with benzonitrile oxide, generated in situ, to give isoxazoline spiro adducts. The cycloadditions were completely regioselective to give the hitherto unreported 3,4-dihydro-2H,4′H-spiro[benzo[f][1,2]thiazepine-5,5′-isoxazole] 1,1-dioxide cycloadduct. Where the N-substituent on the sulfonamide cycloaddition precursor was a 2-substituted arene, the resulting atropisomerism along the N-aryl bond led to facial selectivity in the cycloaddition reaction, with greater than 90 % diastereoselectivity.

Chloroform as a hydrogen atom donor in Barton reductive decarboxylation reactions

The utility of chloroform as both a solvent and a hydrogen atom donor in Barton reductive decarboxylation of a range of carboxylic acids was recently demonstrated (Ko, E. J. et al. Org. Lett. 2011, 13, 1944). In the present work, a combination of electronic structure calculations, direct dynamics calculations, and experimental studies was carried out to investigate how chloroform acts as a hydrogen atom donor in Barton reductive decarboxylations and to determine the scope of this process. The results from this study show that hydrogen atom transfer from chloroform occurs directly under kinetic control and is aided by a combination of polar effects and quantum mechanical tunneling. Chloroform acts as an effective hydrogen atom donor for primary, secondary, and tertiary alkyl radicals, although significant chlorination was also observed with unstrained tertiary carboxylic acids.

Hyperconjugation involving strained carbon-carbon bonds. Application of the variable oxygen probe to ester and ether derivatives of cubylmethanol

Application of the variable oxygen probe to derivatives of (4-methoxycarbonyl)cubylmethanol 11 demonstrated a strong response of C-OR bond distance to the electron demand of the OR substituent, consistent with an enhanced σ-donor ability of the strained C-C bonds of cubane. The extent of cubane donor ability was found to be superior to an unstrained donor 13, comparing data extracted from the Cambridge Structural Database (T. W. Cole, Ph.D. Dissertation, University of Chicago, 1966), but weaker than the previously studied cyclopropane donors. Structural evidence is also found for σCC-π*CO interactions in these structures.

Synthesis of biotinylated episilvestrol: highly selective targeting of the translation factors eIF4AI/II

Silvestrol (1) and episilvestrol (2) are protein synthesis inhibitors, and the former has shown efficacy in multiple mouse models of cancer; however, the selectivity of these potent cytotoxic natural products has not been described. Herein, it is demonstrated that eukaryotic initiation factors eIF4AI/II were the only proteins detected to bind silvestrol (1) and biotinylated episilvestrol (9) by affinity purification. Our study demonstrates the remarkable selectivity of these promising chemotherapeutics.

N-Aryl Atropisomerism Induces Facial Selectivity in Benzonitrile Oxide Cycloadditions with Exocyclic Methylene Benzosultams

N-aryl methylene benzo-fused sultams (2,3-dihydrobenzo[d]isothiazole 1,1-dioxides) underwent [3+2] cycloaddition with benzonitrile oxide to give 5-spiro isoxazoline adducts with complete regioselectivity. Steric hindrance by atropisomerism around the N-aryl bond induced facial selectivity in these cycloadditions.

Synthesis and Self-Assembly of a Peptide - Amphiphile as a Drug Delivery Vehicle

The formation of functional liposomes by the self assembly of a peptide–amphiphile that comprises the neuroprotective tripeptide motif glycyl-prolyl-glutamic acid linked to a hydrophobic moiety is reported. The self-assembled peptide–lipid conjugate displays long range order and can be dispersed as nanometre sized particles.

A Multi-Step Continuous Flow Process for the N-Demethylation of Alkaloids

Dextromethorphan was N-demethylated using the non-classical Polonovski reaction under continuous flow conditions, in two steps: initial N-oxidation with m-chloroperbenzoic acid followed by iron-catalysed N-demethylation of the resulting N-oxide.