Stabilized Palladium Nanoparticles from Bis-(N-benzoylthiourea) Derived-PdII Complexes as Efficient Catalysts for Sustainable Cross-Coupling Reactions in Water

Stable palladium (II) complexes, incorporating a double (N-benzoylthiourea) arrangement bonded to a complex heterocyclic scaffold, are used as precursors of catalytic species able to promote Suzuki-Miyaura, Mizoroki-Heck, Hiyama, Buchwald-Hartwig, Hirao and Sonogashira-Hagihara cross-coupling transformations in water. These sustainable processes are chemoselective and very versatile. The nanoparticles responsible for these catalytic reactions were analyzed and studied. Their usefulness is demonstrated after several tests and analyses. The heterogeneous character of this species in water was also confirmed.

An Innovative Structural Rearrangement in Imine Palladacycle Metaloligand Chemistry: From Single-Nuclear to Double-Nuclear Pseudo-Pentacoordinated Complexes

Treatment of the double nuclear complex 1a, di-μ-cloro-bis[N-(4-formylbenzylidene)cyclohexylaminato-C6, N]dipalladium, with Ph₂PCH₂CH₂)₂PPh (triphos) and NH₄PF₆ gave the single nuclear species 2a, 1-N-(cyclohexylamine)-4-N-(formyl)palladium(triphos)(hexafluorophasphate). Reaction of 2a with Ph₂PCH₂CH₂NH₂ in refluxing chloroform via a condensation reaction of the amine and formyl groups to produce the C=N double bond, gave 3a, 1-N-(cyclohexylamine)-4- N-(diphenylphosphinoethylamine)palladium(triphos)(hexafluorophasphate); a potentially bidentate [N,P] metaloligand. However, attempts to coordinate a second metal by treatment of 3a with [PdCl₂(PhCN)₂] were to no avail. Notwithstanding, complexes 2a and 3a left to stand in solution spontaneously self-transformed to give in either case the double nuclear complex 10, 1,4-N,N-terephthalylidene(cyclohexilamine)-3,6-[bispalladium(triphos)]di(hexafluorophosphate), after undergoing further metalation of the phenyl ring, then bearing two mutually trans [Pd(Ph₂PCH₂CH₂)₂PPh)-P,P,P] moieties: an unprecedented and serendipitous result indeed. On the other hand, reaction of the double nuclear complex 1b, di-μ-cloro-bis[N-(3-formylbenzylidene)cyclohexylaminato-C6, N]dipalladium, with Ph₂PCH₂CH₂)₂PPh (triphos) and NH₄PF₆ gave the single nuclear species 2b, 1-N-(cyclohexylamine)-4-N-(formyl)palladium(triphos)(hexafluorophasphate), Treatment of 2b with H₂O/glacial MeCOOH gave cleavage of the C=N double bond and of the Pd···N interaction, yielding 5b, isophthalaldehyde-6-palladium(triphos)hexafluorophosphate, which then reacted with Ph₂P(CH₂)₃NH₂ to yield complex 6b, N,N-(isophthalylidene(diphenylphosphinopropylamine)-6-(palladiumtriphos)di(hexafluorophosphate), with two pairs of non-coordinated nitrogen and phosphorus donor atoms. Treatment of 6b with [PdCl₂(PhCN)₂], [PtCl₂(PhCN)₂], or [PtMe₂(COD)] gave the new double nuclear complexes 7b, 8b and 9b, palladiumdichloro-, platinumdichloro- and platinumdimethyl[N,N-(isophthalylidene(diphenylphosphinopropylamine)-6-(palladiumtriphos)(hexafluorophosphate)-P,P], respectively, showing the behavior of 6b as a palladated bidentate [P,P] metaloligand. The complexes were fully characterized by microanalysis, IR, ¹H, and ³¹P NMR spectroscopies, as appropriate. The X-ray single-crystal analyses for compounds 10 and 5b have been previously described as the perchlorate salts by JM Vila et al.

Investigation of halogenated furanones as inhibitors of quorum sensing-regulated bioluminescence in Vibrio harveyi

Aim: Vibrio harveyi is a Gram-negative marine bacterium that is a model system in the study of quorum sensing (QS). V. harveyi uses multichannel QS, mediated by three signaling molecules. The aim of this study was to synthesize and screen a diverse series of furanones for their potential to inhibit V. harveyi quorum sensing. Materials & methods: A library of halogenated furanones was prepared and derivatized using standard Pd-mediated coupling reactions and subsequently evaluated for their effects on V. harveyi bioluminescence. Results & conclusion: Several furanones inhibited QS-regulated bioluminescence, with gem-dichlorofuranone and tribromofuranone compounds proving especially effective. Importantly, a number of compounds were effective inhibitors of V. harveyi bioluminescence but did not have an impact on bacterial growth.

How Should We Grade Cervical Disk Degeneration? A Comparison of Two Popular Classification Systems

Introduction

Despite being originally developed for the evaluation of lumbar disk degeneration, the Pfirrmann classification has emerged as the most popular classification system for cervical disk degeneration. However, with the Suzuki classification, a new classification system that is specifically tailored for the evaluation of cervical disk disease was introduced. In this study, we aim to evaluate differences in inter- and intraobserver reliability of both classifications in a head-to-head comparison.

Methods

In total, we have evaluated 120 cervical disks within 40 patients via magnetic resonance imaging according to the Pfirrmann and Suzuki classification. The degree of disk degeneration was evaluated by two independent musculoskeletal radiologists. After 6 months, the classification was reassessed to evaluate the intraobserver reliability. The inter- and intraobserver reliabilities were then calculated using Cohen's kappa.

Results

The inter- and intraobserver reliability provided a significant agreement between all ratings in Pfirrmann as well as the Suzuki classification (p>0.001). The interobserver reliability was determined to be fair in both the Suzuki classification (κ=0.290) and the Pfirrmann classification (κ=0.265). The intraobserver reliability was substantial in the Suzuki classification (κ=0.798), while it was almost perfect in the Pfirrmann classification (κ=0.858).

Conclusions

Although not designed for the evaluation of cervical disk degeneration, the Pfirrmann classification yielded equal inter- and higher intraobserver reliability. Both classification systems are viable options for the grading of cervical disk degeneration. While the Pfirrmann classification has the advantage of being better established, the Suzuki classification may be clinically superior due to a better representation of cervical disk degeneration and the consideration of disk bulging for the classification of cervical disk degeneration.

Cervical disc degeneration reduces distance between vertebral artery and surgical landmarks

PURPOSE

Anterior cervical decompression surgery exposes the vertebral artery to the risk of injury. This risk can increase if the natural course of the vertebral artery is altered. Therefore, this study evaluated if the distance between surgical landmarks and the vertebral artery decrease with the progression of cervical disc degeneration.

METHODS

This study analyzed 40 patients with cervical magnetic resonance imaging. We evaluated the distance between the uncinate process and the vertebral artery in axial-plane T2 weighted sequences of the cervical levels C3-C6. The cervical disc degeneration was graded according to the Pfirrmann- and Suzuki classification. The decrease of the distance was evaluated using a one-way ANOVA.

RESULTS

The distance between the uncinate process and the vertebral artery decreased with increasing disc degeneration (p ≤ 0.015). ROC analysis provided an acceptable area under the curve in both classifications for the detection of a vertebral artery to the uncinate process distance of zero. The presence of Pfirrmann grade V had a positive predictive value of 69% for the presence of contact between the uncinate process and the vertebral artery.

CONCLUSION

High-grade cervical disc degeneration according to the Pfirrmann- and the Suzuki classification decrease the distance between the uncinate process and the vertebral artery. High-grade disc degeneration therefore should raise the awareness of the surgeon for the loss of the distance between surgical landmarks and the vertebral artery. However, screening for high-grade disc degeneration alone cannot substitute the thorough evaluation of the anatomical course of the vertebral artery before surgery.

Identification and characterization of the binding sequences and target genes of p53 lacking the 1st transactivation domain

The tumor suppressor gene p53 encodes a transcriptional activator that has two transactivation domains (TAD) located in its amino terminus. These two TAD can transactivate genes independently, and at least one TAD is required for p53 transactivation function. The 1st TAD (a.a. 1‐40) is essential for the induction of numerous classical p53 target genes, while the second TAD (a.a. 41‐61) suffices for tumor suppression, although its precise molecular function remains unclear. In this study, we comprehensively identified the sites to which p53 lacking the 1st TAD (Δ1stTAD‐p53) binds, as well as its potential target genes. We found that the binding sequences for Δ1stTAD‐p53 are divergent and include not only the canonical p53 consensus binding sequences but also sequences similar to those recognized by a number of other known transcription factors. We identified and analyzed the functions of three Δ1stTAD‐p53 target genes, PTP4A1, PLK2 and RPS27L. All three genes were induced by both full‐length p53 and Δ1stTAD‐p53, and were dependent on the transactivation activity of the 2nd TAD. We also found that two of these, PTP4A1 and PLK2, are endoplasmic reticulum (ER) stress‐inducible genes. We found that upon ER stress, PTP4A1 suppresses apoptosis while PLK2 induces apoptosis. These results reveal a novel Δ1stTAD‐p53 downstream pathway that is dependent on the transcription activation activity of the 2nd TAD.

DNA-Encoded Libraries: Aryl Fluorosulfonates as Versatile Electrophiles Enabling Facile On-DNA Suzuki, Sonogashira, and Buchwald Reactions

Using (hetero)aryl fluorosulfonates as versatile electrophiles, facile on-DNA cross-coupling reactions of Suzuki, Sonogashira, and Buchwald are reported here. Notably, all of these reactions show excellent functional group tolerance, mild reaction conditions (relative low temperature and open to air), rich heterocyclic coupling partners, and more importantly, DNA-compatibility. Thus, these new reactions based on efficient formation of C(sp2)-C(sp2), C(sp2)-C(sp), and C(sp2)-N bonds are highly amenable to synthesis of DNA-encoded libraries with great molecular diversity.

Highly bulky and stable geometry-constrained iminopyridines: Synthesis, structure and application in Pd-catalyzed Suzuki coupling of aryl chlorides

A series of bulky geometry-constrained iminopyridylpalladium chlorides were developed. The steric environment adjacent to the nitrogen atom in the pyridine rings and diimine parts enhanced the thermal stability of the palladium species. Bulkier groups at the imino group stabilized the palladium species and the corresponding palladium chlorides showed high activities in the coupling reaction of aryl chlorides.