Superfast Capture of Iodine from Air, Water, and Organic Solvent by Potential Dithiocarbamate-Based Organic Polymer.

Organic polymers are widely explored due to their high stability, scalability, and more facile modification properties. We developed cost-effective dithiocarbamate-based organic polymers synthesized using diamides, carbon disulfide, and diamines to apply for environmental remediation. The sequestration of radioiodine is a serious concern to tackle when dealing with nuclear power for energy requirements. However, many of the current sorbents have the problem of slower adsorption for removing iodine. In this report, we discuss the utilization of an electron-rich dithiocarbamate-based organic polymer for the removal of iodine in a very short time and with high uptake. Our material showed 2.8 g/g uptake of vapor iodine in 1 h, 915.19 mg/g uptake of iodine from cyclohexane within 5 s, 93% removal of saturated iodine from water in 1 min, and 1250 mg/g uptake of triiodide ions from water within 30 s. To the best of our knowledge, the iodine capture was faster than previously observed for any existing material. The material was fully recyclable when applied for up to four cycles. Hence, this dithiocarbamate-based polymer can be a promising system for the fast removal of various forms of iodine and, thus, enhance environmental security.

Chemical Probes and Activity-Based Protein Profiling for Cancer Research.

Chemical probes can be used to understand the complex biological nature of diseases. Due to the diversity of cancer types and dynamic regulatory pathways involved in the disease, there is a need to identify signaling pathways and associated proteins or enzymes that are traceable or detectable in tests for cancer diagnosis and treatment. Currently, fluorogenic chemical probes are widely used to detect cancer-associated proteins and their binding partners. These probes are also applicable in photodynamic therapy to determine drug efficacy and monitor regulating factors. In this review, we discuss the synthesis of chemical probes for different cancer types from 2016 to the present time and their application in monitoring the activity of transferases, hydrolases, deacetylases, oxidoreductases, and immune cells. Moreover, we elaborate on their potential roles in photodynamic therapy.

Aza-Oxa-Triazole Based Macrocycles with Tunable Properties: Design, Synthesis, and Bioactivity.

A modular platform for the synthesis of tunable aza-oxa-based macrocycles was established. Modulations in the backbone and the side-chain functional groups have been rendered to achieve the tunable property. These aza-oxa-based macrocycles can also differ in the number of heteroatoms in the backbone and the ring size of the macrocycles. For the proof of concept, a library of macrocycles was synthesized with various hanging functional groups, different combinations of heteroatoms, and ring sizes in the range of 17-27 atoms and was characterized by NMR and mass spectrometry. In light of the importance of the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction and the significance of triazole groups for various applications, we employed the click-reaction-based macrocyclization. The competence of the synthesized macrocycles in various biomedical applications was proven by studying the interactions with the serum albumin proteins; bovine serum albumin and human serum albumin. It was observed that some candidates, based on their hanging functional groups and specific backbone atoms, could interact well with the protein, thus improving the bioactive properties. On the whole, this work is a proof-of-concept to explore the backbone- and side-chain-tunable macrocycle for different properties and applications.

A new skeletal rearrangement of 1,7-dimethyl Cookson's cage dione catalyzed by a Lewis acid.

A methyl-substituted polycyclic cage dione containing the PCUD framework has undergone an unprecedented ring rearrangement approach. Here, the PCUD framework with the aid of a Lewis acid such as BF3·MeOH gave unusual fragmentation products. Two new products were isolated via the skeletal rearrangement process involving carbocation mediated intermediates. The substituents in the succinyl bond present in the strained PCUD skeleton produce a driving force for the rearrangement in an unprecedented manner. Interestingly, the cyclobutane ring was transformed to cyclopentane through the cleavage of the C1-C7 bond during the ring-expansion process of PCUD via the carbocation intermediates. Unexpectedly, solvent (benzene) was captured during the ring-homologation process due to the presence of methyl substituents placed at the cyclobutane ring of the cage framework. It appears that this is the first report where an unexpected ring-rearrangement, ring-homologation, and ring-fragmentation occur with the aid of the BF3·MeOH complex.

7-Meth-oxy-penta-cyclo-[5.4.0.02,6.03,10.05,9]undec-ane-8,11-dione.

The structure of 7-meth-oxy-penta-cyclo-[5.4.0.02,6.03,10.05,9]undecane-8,11-dione, C12H12O3, at 150 K has monoclinic (P21/c) symmetry. The penta-cyclo-undecane cage compound is composed of four five-membered rings, a planar four-membered ring and a six-membered ring in a boat conformation fused into a closed strained-cage framework. All of the five-membered rings adopt an envelope conformation.

Synthetic Approach to the ABCD Ring System of Anticancer Agent Fredericamycin A via Claisen Rearrangement and Ring-Closing Metathesis as Key Steps.

A new synthetic strategy to the ABCD ring system of the anticancer agent fredericamycin A (NSC-305263) was realized by the Diels-Alder reaction and olefin metathesis as key steps. The tactics developed here for the construction of the ABCD ring system also involve double Claisen rearrangement followed by a retro-Diels-Alder reaction and ring-closing metathesis. The metathesis approach performs a key role in the construction of A and D rings of the ABCD core unit. More importantly, ABCD fragment synthesis was accomplished without the involvement of protecting groups.

Molecular Acrobatics in Polycyclic Frames: Synthesis of Functionalized D3-Trishomocubanes via the Rearrangement Approach.

A new synthetic route to D3-trishomocubanone and oxa- D3-trishomocubane derivatives has been established by the rearrangement approach. A remotely located methyl substituent in the six-membered ring contributed to the acid-catalyzed rearrangement of the cage dione in an unusual fashion. This rearrangement approach provided an attractive route to extended D3-trishomocubanes, which are not accessible by the conventional multistep synthetic sequence. For the first time, two phenyl groups were incorporated from the solvent into the strained trishomocubane skeleton in an unprecedented manner via carbocation-mediated rearrangement with the aid of BF3·OEt2. Interestingly, an oxa-bridged trishomocubane skeleton was also formed during acid-promoted rearrangement.