Probing the Mechanism of Action of Bis(phenolato) Amine (ONO Donor Set) Titanium(IV) Anticancer Agents

The need for anticancer therapies that overcome metallodrug resistance while minimizing adverse toxicities is targeted, herein, using titanium coordination complexes. Octahedral titanium(IV) trans,mer-[Ti{R1N(CH2-2-MeO-4-R1-C6H2)2}2] [R1 = Et, allyl, n-Pr, CHO, F, CH2(morpholino), the latter from the formyl derivative; R2 = Me, Et; not all combinations] are attained from Mannich reactions of commercial 2-methoxyphenols (27-74% overall yield, 2 steps). These crystalline (four X-ray structures) Ti(IV)-complexes are active against MCF-7, HCT-116, HT-29, PANC-1, and MDA-MB-468 cancer cell lines (GI50 = 0.5-38 μM). Their activity and cancer selectivity (vs nontumor MRC-5 cells) typically exceeds that of cisplatin (up to 16-fold). Proteomic analysis (in MCF-7) supported by other studies (G2/M cell cycle arrest, ROS generation, γH2AX production, caspase activation, annexin positivity, western blot, and kinase screens in MCF-7 and HCT-116) suggest apoptosis elicited by more than one mechanism of action. Comparison of these data to the modes of action proposed for salan Ti(IV) complexes is made.

Synthesis of hydrazinylthiazole carboxylates: a mechanistic approach for treatment of diabetes and its complications

Aim: The deaths of thousands of people and millions affected by diabetes mellitus triggered us to look for alternative possible solutions to cure diabetes and its complications. Materials & methods: A series of hydrazinylthiazole carboxylates (3a-n) was prepared by cyclocondensation reaction of thiosemicarbazones with ethyl 2-chloroacetoacetate. These compounds were screened for antidiabetic potential through α-amylase inhibition, antiglycation and antioxidant assays. Results & conclusion: Most of the compounds exhibited a promising antidiabetic property. Compounds 3e and 3h showed excellent α-amylase and glycation inhibition properties. The hemolytic assay indicated that all compounds are biocompatible. Docking studies carried out on α-amylase target showed correlation between in vitro inhibition and binding energy.

Synthesis of Fluorinated Hydrazinylthiazole Derivatives: A Virtual and Experimental Approach to Diabetes Management

A novel series of fluorophenyl-based thiazoles was synthesized following the Hanztsch method. All of the compounds were initially verified with physical parameters (color, melting point, retardation factor (R _f)), which were further confirmed by several spectroscopic methods, including ultraviolet-visible (UV-visible), Fourier-transform infrared (FTIR), ¹H, ¹³C, ¹⁹F NMR, and high-resolution mass spectrometry (HRMS). The binding interactions of all compounds were studied using a molecular docking simulation approach. Furthermore, each compound was evaluated for its alpha(α)-amylase, antiglycation, and antioxidant potentials. The biocompatibility of all compounds was checked with an in vitro hemolytic assay. All synthesized scaffolds were found biocompatible with minimal lysis of human erythrocytes as compared to the standard Triton X-100. Among the tested compounds, the analogue 3h (IC₅₀ = 5.14 ± 0.03 μM) was found to be a highly potent candidate against α-amylase as compared to the standard (acarbose, IC₅₀ = 5.55 ± 0.06 μM). The compounds 3d, 3f, 3i, and 3k exhibited excellent antiglycation inhibition potential with their IC₅₀ values far less than the standard amino guanidine (IC₅₀ = 0.403 ± 0.001 mg/mL). The antidiabetic potential was further supported by docking studies. Docking studies revealed that all synthesized compounds exhibited various interactions along enzyme active sites (pi-pi, H-bonding, van der Waals) with varied binding energies.

Safety and efficacy of tenecteplase in patients with wake-up stroke assessed by non-contrast CT (TWIST): a multicentre, open-label, randomised controlled trial

BACKGROUND

Current evidence supports the use of intravenous thrombolysis with alteplase in patients with wake-up stroke selected with MRI or perfusion imaging and is recommended in clinical guidelines. However, access to advanced imaging techniques is often scarce. We aimed to determine whether thrombolytic treatment with intravenous tenecteplase given within 4·5 h of awakening improves functional outcome in patients with ischaemic wake-up stroke selected using non-contrast CT.

METHODS

TWIST was an investigator-initiated, multicentre, open-label, randomised controlled trial with blinded endpoint assessment, conducted at 77 hospitals in ten countries. We included patients aged 18 years or older with acute ischaemic stroke symptoms upon awakening, limb weakness, a National Institutes of Health Stroke Scale (NIHSS) score of 3 or higher or aphasia, a non-contrast CT examination of the head, and the ability to receive tenecteplase within 4·5 h of awakening. Patients were randomly assigned (1:1) to either a single intravenous bolus of tenecteplase 0·25 mg per kg of bodyweight (maximum 25 mg) or control (no thrombolysis) using a central, web-based, computer-generated randomisation schedule. Trained research personnel, who conducted telephone interviews at 90 days (follow-up), were masked to treatment allocation. Clinical assessments were performed on day 1 (at baseline) and day 7 of hospital admission (or at discharge, whichever occurred first). The primary outcome was functional outcome assessed by the modified Rankin Scale (mRS) at 90 days and analysed using ordinal logistic regression in the intention-to-treat population. This trial is registered with EudraCT (2014-000096-80), ClinicalTrials.gov (NCT03181360), and ISRCTN (10601890).

FINDINGS

From June 12, 2017, to Sept 30, 2021, 578 of the required 600 patients were enrolled (288 randomly assigned to the tenecteplase group and 290 to the control group [intention-to-treat population]). The median age of participants was 73·7 years (IQR 65·9-81·1). 332 (57%) of 578 participants were male and 246 (43%) were female. Treatment with tenecteplase was not associated with better functional outcome, according to mRS score at 90 days (adjusted OR 1·18, 95% CI 0·88-1·58; p=0·27). Mortality at 90 days did not significantly differ between treatment groups (28 [10%] patients in the tenecteplase group and 23 [8%] in the control group; adjusted HR 1·29, 95% CI 0·74-2·26; p=0·37). Symptomatic intracranial haemorrhage occurred in six (2%) patients in the tenecteplase group versus three (1%) in the control group (adjusted OR 2·17, 95% CI 0·53-8·87; p=0·28), whereas any intracranial haemorrhage occurred in 33 (11%) versus 30 (10%) patients (adjusted OR 1·14, 0·67-1·94; p=0·64).

INTERPRETATION

In patients with wake-up stroke selected with non-contrast CT, treatment with tenecteplase was not associated with better functional outcome at 90 days. The number of symptomatic haemorrhages and any intracranial haemorrhages in both treatment groups was similar to findings from previous trials of wake-up stroke patients selected using advanced imaging. Current evidence does not support treatment with tenecteplase in patients selected with non-contrast CT.

FUNDING

Norwegian Clinical Research Therapy in the Specialist Health Services Programme, the Swiss Heart Foundation, the British Heart Foundation, and the Norwegian National Association for Public Health.

Catalysis enabled synthesis, structures, and reactivities of fluorinated S8-corona[n]arenes (n = 8-12)

Previously inaccessible large S₈-corona[n]arene macrocycles (n = 8-12) with alternating aryl and 1,4-C₆F₄ subunits are easily prepared on up to gram scales, without the need for chromatography (up to 45% yield, 10 different examples) through new high acceleration S_NAr substitution protocols (catalytic NR₄F in pyridine, R = H, Me, Bu). Macrocycle size and functionality are tunable by precursor and catalyst selection. Equivalent simple NR₄F catalysis allows facile late-stage S_NAr difunctionalisation of the ring C₆F₄ units with thiols (8 derivatives, typically 95+% yields) providing two-step access to highly functionalised fluoromacrocycle libraries. Macrocycle host binding supports fluoroaryl catalytic activation through contact ion pair binding of NR₄F and solvent inclusion. In the solid-state, solvent inclusion also intimately controls macrocycle conformation and fluorine-fluorine interactions leading to spontaneous self-assembly into infinite columns with honeycomb-like lattices.

Identifying Chirality in Line Drawings of Molecules Using Imbalanced Dataset Sampler for a Multilabel Classification Task

Chirality, the ability of some molecules to exist as two non-superimposable mirror images, profoundly influences both chemistry and biology. Advances in deep learning enable the automatic recognition of chemical structure diagrams, however, studies on discovering the molecule chirality are scarce and the machine-readable molecular representations are not always sufficient to fully support the encoding of this important property. Here, we pretrained networks on a ChEMBL+ dataset (79641 molecules) and fine-tuned them for the binary classification of chirality (achiral/chiral) or multilabel chirality type classifications (none/centre/axial/planar). To address the label combination imbalanced problem in the multilabel task, the study proposed a Formulated Imbalanced Dataset Sampler (FIDS) to sample a formulated amount of minority label combinations on top of the training set. On a 10-fold cross validation experiment using our CHIRAL dataset (1142 manually curated molecules), our models achieved up to an accuracy of 90 % in the binary task. In the multilabel task incorporated with FIDS, the overall performance increases from 87 % to 89 % and the accuracy per label combination can attained up to a 50 % increase. Through the study of heatmaps, our work also exemplified the potential of deep neural network to make predictions based on the actual location of chirality elements.

Design, and synthesis of selectively anticancer 4-cyanophenyl substituted thiazol-2-ylhydrazones

Cyclization of substituted thiosemicarbazones with α-bromo-4-cyanoacetophenone allows rapid single-step sustainable syntheses of 4-cyanophenyl-2-hydrazinylthiazoles libraries (30 examples, 66-79%). All show anticancer efficacy against HCT-116 and MCF-7 carcinoma cell lines with the majority being more active than cisplatin positive controls. The compounds 2-(2-(2-hydroxy-3-methylbenzylidene)hydrazinyl)-4-(4-cyanophenyl)thiazole (3f) and 2-(2-((pentafluorophenyl)methylene)-hydrazinyl)-4-(4-cyanophenyl)thiazole (3a') show optimal GI50 values (1.0 ± 0.1 μM and 1.7 ± 0.3 μM) against MCF-7 breast cancer cells. Against colorectal carcinoma HCT-116 cells, (2-(2-(3-bromothiophen-2-yl)methylene)hydrazinyl)-4-(4-cyanophenyl)thiazole (3b'), 2-(2-(2-hydroxy-3-methylbenzylidene)hydrazinyl)-4-(4-cyanophenyl)thiazole (3f), 2-(2-(2,6-dichlorobenzylidene)hydrazinyl)-4-(4-cyanophenyl)thiazole (3n) and 2-(2-(1-(4-fluorophenyl)ethylidene)hydrazinyl)-4-(4-cyanophenyl)thiazole (3w) are the most active (GI50 values: 1.6 ± 0.2, 1.6 ± 0.1, 1.1 ± 0.5 and 1.5 ± 0.8 μM respectively). Control studies with MRC-5 cells indicate appreciable selectivity towards the cancer cells targeted. Significant (p < 0.005) growth inhibition and cytotoxicity effects for the thiazoles 3 were corroborated by cell count and clonogenic assays using the same cancer cell lines at 5 and 10 μM agent concentrations. Cell cycle, caspase activation and Western blot assays demonstrated that compounds 3b' and 3f induce cancer cell death via caspase-dependent apoptosis. The combination of straight forward synthesis and high activity makes the thiazoles 3 an interesting lead for further development.

Synthesis of Arylidenehydrazinyl-4-methoxyphenylthiazole Derivatives: Docking Studies, Probing Type II Diabetes Complication Management Agents

Thiazole has been a key scaffold in antidiabetic drugs. In quest of new and more effective drugs a simple, efficient, high yielding (67-79%) and convenient synthesis of arylidenehydrazinyl-4-methoxyphenyl)thiazoles is accomplished over two steps. The synthesis involved the condensation of aryl substituted thiosemicarbazones and 2-bromo-4-methoxyacetophenone in absolute ethanol. The structures of the resulting thiazoles are in accord with their UV-Vis, FT-IR, 1 H-, 13 C-NMR and HRMS data. All compounds were evaluated for alpha(α)-amylase inhibition potential, antiglycation, antioxidant abilities and biocompatibility. The compounds library identified 2-(2-(3,4-dichlorobenzylidene)hydrazinyl)-4-(4-methoxyphenyl)thiazole as a lead molecule against α-amylase inhibition with an IC 50 of 5.75±0.02 µM. α-Amylase inhibition is also supported by molecular docking studies against amylase. All the obtained thiazoles also showed promising antiglycation activity with 4-(4-methoxyphenyl)-2-(2-(2-(trifluoromethyl)benzylidene)hydrazinyl)thiazole exhibiting the best inhibition (IC 50 = 0.383±0.001 mg/mL) compared to control. The tested compounds are also biocompatible at the concentration used i.e. 10 µM.

Rate of Formation of Industrial Lubricant Additive Precursors from Maleic Anhydride and Polyisobutylene

The Alder-ene reaction of neat polyisobutylene (PIB) and maleic anhydride (MAA) to produce the industrially important lubricant additive precursor polyisobutylene succinic anhydride (PIBSA) is studied at 150–180 °C. Under anaerobic conditions with [PIB] ∼ 1.24 M (550 g mol^–1 grade, >80% exo alkene) and [MAA] ∼ 1.75 M, conversion of exo-PIB and MAA follows second-order near-equal rate laws with k_obs up to 5 × 10^–5 M^–1 s^–1 for both components. The exo-alkene-derived primary product PIBSA-I is formed at an equivalent rate. The less reactive olefinic protons of exo-PIB also react with MAA to form isomeric PIBSA-II (k_obs up to 6 × 10^–5 M^–1 s^–1). Some exo-PIB is converted to endo-PIB (containing trisubstituted alkene) in a first-order process (k_obs ∼ 1 × 10^–5 s^–1), while PIBSA-I is difunctionalized by MAA to bis-PIBSAs very slowly. The MAA- and PIB-derived activation parameter ΔG^‡(150 °C) 34.3 ± 0.3 kcal mol^–1 supports a concerted process, with that of PIBSA-I suggesting a late (product-like) transition state.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

1074 Fear Reactivity And Sleep In Trauma-Exposed Males And Females With And Without PTSD

Introduction

Sleep disturbance is considered central to mechanisms of PTSD development and maintenance, and fear learning protocols have been used as laboratory models to understand PTSD disease mechanisms. Some research indicates that fear learning may influence subsequent sleep, especially REM sleep, and that sleep may influence subsequent extinction. In this study, we examined the relationship of startle reactivity during conditioning and later extinction with objectively-measured sleep in PTSD-positive and negative subjects.

Methods

These analyses were performed as part of a larger study of PTSD and sleep. Thirty-four (34) trauma-exposed male and female participants with and without PTSD completed a fear-potentiated startle conditioning procedure at 9:45am, followed by a PSG-monitored nap (13:30-15:30), followed by an extinction protocol at 4:30pm. All visits were preceded by an adaptation nap visit at least 7 days prior. Eye-blink EMG was used to measure startle reactivity. Mixed-model analyses were performed in SPSS.

Results

PTSD-positive subjects had higher REM sleep duration (p&lt;.05) and a trend towards shorter REM sleep latency (p=.06). There were no other group or sex effects on standard PSG sleep parameters. During conditioning, PTSD-positive status was associated with higher startle reactivity across stimulus types (p&lt;.01), driven by increased reactivity in PTSD-positive vs. PTSD-negative females. A PTSD x sex interaction effect on startle reactivity showed the opposite effect in males (p&lt;.01). Higher startle reactivity during conditioning predicted longer sleep latency during the subsequent nap (p&lt;.05), but reactivity during conditioning and extinction did not otherwise show a relationship to standard PSG sleep measures.

Conclusion

These findings are consistent with previous research indicating REM sleep abnormalities as well as heightened fear responses in PTSD. While the observed relationship between higher startle and longer sleep latency is consistent with studies indicating that stress affects subsequent sleep, further research in larger samples is needed to understand causal mechanisms and to advance our understanding of sleep-PTSD mechanisms.

Support

VA Career Development Award-5IK2CX000871-05

Dewar Benzenoids Discovered In Carbon Nanobelts

The synthesis of cyclacene nanobelts remains an elusive goal dating back over 60 years. These molecules represent the last unsynthesized building block of carbon nanotubes and may be useful both as seed molecules for the preparation of structurally well-defined carbon nanotubes and for understanding the behavior and formation of zigzag nanotubes more broadly. Here we report the discovery that isomers containing two Dewar benzenoid rings are the preferred form for several sizes of cyclacene. The predicted lower polyradical character and higher singlet-triplet stability that these isomers possess compared with their pure benzenoid counterparts suggest that they may be more stable synthetic targets than the structures that have previously been identified. Our findings should facilitate the exploration of new routes to cyclacene synthesis through Dewar benzene chemistry.

The potential to quantify polypharmacy in older adult hospital inpatients using electronic prescribing software: a feasibility study

Polypharmacy in older adults is a growing problem, as some drugs may be either unnecessary or even harmful. Admission to hospital under a Medicine for the Elderly specialist physicians represents an opportunity to review patients’ medication. The recent introduction of electronic prescribing to some hospitals in the United Kingdom allows the development of tools to measure polypharmacy in in-patients, and subsequently to assess the efficacy of interventions that aim to optimize medication prescribing. We tested the feasibility of developing an Excel-based software code that measured the number of medications a group of patients were taking at admission and how many of these were still prescribed on discharge. Electronic prescribing data was obtained from the Royal Derby Hospital, over a period of 52 weeks from April 2017 to March 2018 for all patients over the age of 65 years who were admitted onto the medicine for the elderly wards and subsequently discharged. On admission, the median number of eligible medications was 11 (interquartile range IQR 8 to 15). At the time of discharge, the median number of eligible medications retained since admission was 9 (IQR 6 to 12). This represents a median number of medications that have been removed from the current medication regimen of 2 (IQR 1 to 3, p < 0.001). Electronic prescribing software in hospitals allows the development of tools to measure the burden of medications, and to examine the efficacy of future interventions that are developed to optimize drug prescribing in older adults.

Syntheses of 7-Substituted Anthra[2,3- b]thiophene Derivatives and Naphtho[2,3- b:6,7- b']dithiophene

7-R-Anthra[2,3- b]thiophene derivatives (1, R = H, Me, i-Pr, or MeO) are prepared in three steps (in average overall yield >50%) starting from ( E)-4-RC₆H₄CH₂(HOCH₂)C═CI(CH₂OH). The latter are commercial or readily prepared from 2-butyne-1,4-diol and ArCH₂Cl (both costing <1 cent/mmol) at 10 g scales. These allow for the selective formation of (otherwise unattainable) higher solubility 7-derivatives. Similar methods allow for the preparation of naphtho[2,3- b:6,7- b']dithiophene 2 using equally low-cost starting materials.

Capturing Waste Heat Energy with Charge-Transfer Organic Thermoelectrics

Electrically conducting organic salts, known for over 60 years, have recently demonstrated new abilities to convert waste heat directly into electrical power via the thermoelectric effect. Multiple opportunities are emerging for new structure–property relationships and for new materials to be obtained through synthetic organic chemistry. This review highlights key aspects of this field, which is complementary to current efforts based on polymeric, nanostructured or inorganic thermoelectric materials and indicates opportunities whereby mainstream organic chemists can contribute.

1 What Are Thermoelectrics? And Why Use Them?

2 Current Organic and Hybrid Thermoelectrics

3 Unique Materials from Tetrathiotetracenes

4 Synthesis of Tetrathiotetracenes

5 Materials and Device Applications

6 Future Perspectives

Enantioselective Synthesis of 6,6-Disubstituted Pentafulvenes Containing a Chiral Pendant Hydroxy Group

Simple enantioselective synthesis of 6,6-disubstituted pentafulvenes bearing chiral pendant hydroxy groups are attained by cascade reactivity using commercially available proline-based organocatalysts. Condensation of cyclopentadiene with the acetyl function of a 1,2-formylacetophenone, followed by cyclization of a resulting fulvene-stabilized carbanion with the formyl group, generates bicyclic chiral alcohols with initial er values up to 94:6. Exceptional enantio-enrichment of the resultant alcohols results upon crystallization-even near racemic samples spontaneously de-racemize. This enables new families of substituted cyclopentadienes that are both enantiomerically and diastereomerically pure to be rapidly attained.

Straightforward Synthesis of 2- and 2,8-Substituted Tetracenes

A simple regiospecific route to otherwise problematic substituted tetracenes is described. The diverse cores (E)-1,2-Ar¹ CH₂ (HOCH₂ )C=C(CH₂ OH)I (Ar¹ =Ph, 4-MePh, 4-MeOPh, 4-FPh) and (E)-1,2-I(HOCH₂ )C=C(CH₂ OH)I, accessed from ultra-low cost HOCH₂ C≡CCH₂ OH at multi-gram scales, allow the synthesis of diol libraries (E)-1,2-Ar¹ CH₂ (HOCH₂ )C=C(CH₂ OH)CH₂ Ar² (Ar² =Ph, 4-MePh, 4-iPrPh, 4-MeOPh, 4-FPh, 4-BrPh, 4-biphenyl, 4-styryl; 14 examples) by efficient Negishi coupling. Copper-catalysed aerobic oxidation cleanly provides dialdehydes (E)-1,2-Ar¹ CH₂ (CHO)C=C(CHO)CH₂ Ar² , which in many cases undergo titanium(IV) chloride-induced double Bradsher closure, providing a convenient method for the synthesis of regiochemically and analytically pure tetracenes (12 examples). The sequence is typically chromatography-free, scalable, efficient and technically simple to carry out.

Low-Cost and Sustainable Organic Thermoelectrics Based on Low-Dimensional Molecular Metals

Thermoelectric generator composed of crystalline radical ion salts: The unipolar charge transport along the molecular stacks facilitates complementary p- and n-type organic thermoelectric materials of high electrical conductivity and of 1D electronic structure. The specific power output of 5 mW cm^-2 and the zT > 0.15 below 40 K demonstrate a new field of low-temperature thermoelectric applications unlocked by organic metals.

Using titanium complexes to defeat cancer: the view from the shoulders of titans

Seeking ‘unifying mechanisms of action’ in titanium anti-cancer agents: a 40 year odyssey.

Enantiopure titanocene complexes--direct evidence for paraptosis in cancer cells

Tolerated by normal tissues, anti-cancer therapies based on titanium compounds are limited by low efficacy/selectivity and lack of understanding of their mode(s) of action. In vitro antitumour activity and mode of cell death incurred by enantiopure TiCl2{η-C5H4CHEt(2-MeOPh)}2 (abbreviated Cp(R)2TiCl2) has been investigated. The in vitro anti-tumour activity of Cp(R)2TiCl2 is selective for cancer cells; in clonogenic assays, (S,S)-Cp(R)2TiCl2 was twice as effective at inhibiting colony formation than other stereoisomers after 24 h exposure. HPLC, MS and NMR techniques determined hydrolysis of Cp(R)2TiCl2; data strongly correlate with soluble [Cp(R)2Ti(OH)(OH2)](+) being the biological trigger. Treatment of cells with Cp(R)2TiCl2 provoked extensive cytoplasmic vacuolization, endoplasmic reticulum (ER) swelling and activation of MAPKinase signal transduction, consistent with ligand-induced paraptosis, type III cell death, which is morphologically distinct from, and independent of apoptosis. Indeed, distinct from cisplatin, Cp(R)2TiCl2 failed to perturb cell cycle dynamics, induce γH2AX foci or evoke apoptosis in MDA-MB-468 and HCT-116 cells.

Diversification of ortho-Fused Cycloocta-2,5-dien-1-one Cores and Eight- to Six-Ring Conversion by σ Bond C-C Cleavage

Sequential treatment of 2-C6 H4 Br(CHO) with LiC≡CR(1) (R(1) =SiMe3 , tBu), nBuLi, CuBr⋅SMe2 and HC≡CCHClR(2) [R(2) =Ph, 4-CF3 Ph, 3-CNPh, 4-(MeO2 C)Ph] at -50 °C leads to formation of an intermediate carbanion (Z)-1,2-C6 H4 {CA (=O)C≡CB R(1) }{CH=CH(CH(-) )R(2) } (4). Low temperatures (-50 °C) favour attack at CB leading to kinetic formation of 6,8-bicycles containing non-classical C-carbanion enolates (5). Higher temperatures (-10 °C to ambient) and electron-deficient R(2) favour retro σ-bond C-C cleavage regenerating 4, which subsequently closes on CA providing 6,6-bicyclic alkoxides (6). Computational modelling (CBS-QB3) indicated that both pathways are viable and of similar energies. Reaction of 6 with H(+) gave 1,2-dihydronaphthalen-1-ols, or under dehydrating conditions, 2-aryl-1-alkynylnaphthlenes. Enolates 5 react in situ with: H2 O, D2 O, I2 , allylbromide, S2 Me2 , CO2 and lead to the expected C-E derivatives (E=H, D, I, allyl, SMe, CO2 H) in 49-64 % yield directly from intermediate 5. The parents (E=H; R(1) =SiMe3 , tBu; R(2) =Ph) are versatile starting materials for NaBH4 and Grignard C=O additions, desilylation (when R(1) =SiMe) and oxime formation. The latter allows formation of 6,9-bicyclics via Beckmann rearrangement. The 6,8-ring iodides are suitable Suzuki precursors for Pd-catalysed C-C coupling (81-87 %), whereas the carboxylic acids readily form amides under T3P® conditions (71-95 %).

Efficient Preparation of TMSCCl2 Br and Its Use in Dichlorocyclopropanation of Electron-Deficient Alkenes

The reaction of excess TMSCl and LiCCl2 Br at low temperature is a technically simple high yield route to TMSCCl2 Br. The latter is a stable source of the dichlorobromomethide carbanion, which undergoes 1,4-addition with cyclic nitroalkenes and (E)-fumarates leading to dichlorocyclopropanes after bromide expulsion. For nitrostyrenes the reaction arrests at the 1,4-addition product. Low temperature NMR spectroscopy studies and DFT calculations suggest the formation of an "ate" species [(nitronate)SiFMe3 ](-) which, upon boil-off of TMSF at 10-20 °C, yields the cyclopropane. DFT calculations also support the experimental differences between fluoride and acetate as promotors.

Correction: Enantiopure titanocene complexes--direct evidence for paraptosis in cancer cells

Correction for 'Enantiopure titanocene complexes--direct evidence for paraptosis in cancer cells' by Melchior Cini et al., Metallomics, 2016, DOI: 10.1039/c5mt00297d.

Asymmetric Pentafulvene Carbometalation--Access to Enantiopure Titanocene Dichlorides of Biological Relevance

Unprecedented asymmetric copper-catalyzed addition of ZnEt2 (ZnBu2) to the exocyclic C=C bond of pentafulvenes C5H4(=CHAr) (Ar=2-MeOPh and related species) results in enantiomerically enriched (up to 93:7 e.r.) cyclopentadienyl ligands (C5H4CHEtAr; abbreviated Cp(R)). Copper catalyst promotion with both chiral phosphoramidite ligands and a phosphate additive is vital in realizing both acceptable enantioselectivities and reaction rates. Enantiomeric Cp(R)2TiCl2 complexes have been prepared; the (S,S) isomer is twice as active towards pancreatic, breast, and colon cancer cell lines as its (R,R) enantiomer at 24 h.

One-Pot Cannizzaro Cascade Synthesis of ortho-Fused Cycloocta-2,5-dien-1-ones from 2-Bromo(hetero)aryl Aldehydes

An intramolecular Cannizzaro-type hydride transfer to an in situ prepared allene enables the synthesis of ortho-fused 4-substituted cycloocta-2,5-dien-1-ones with unprecedented technical ease for an eight-ring carboannulation. Various derivatives could be obtained from commercially available (hetero)aryl aldehydes, trimethylsilylacetylene, and simple propargyl chlorides in good yields.