Non-Noble Metal-Catalyzed Carbonylative Multi-Component Reactions

Carbonylative multi-component reactions (CMCR), having four or more kinds of starting materials, provide an efficient strategy for the preparation of polyfunctional carbonylated compounds. Diverse CMCR utilizing non-noble transition-metal catalysts have been developed. This review summarized and discussed the recent advances in non-noble metal-catalyzed carbonylative multi-component reactions.

Cytotoxic Dehydroabietylamine Derived Compounds

BACKGROUND AND METHODS

Chemotherapy remains one of the most important methods for the treatment of cancer. More recently in this context, some products derived from natural products have raised scientific interest which especially include many terpenes. Thereby, diterpenoids represent a special class, and within this class of important secondary natural products, especially compounds derived from Dehydroabietylamine (DA), are of particular interest.

RESULTS

This review not only gives a summary of the most important findings on the cytotoxic behavior of DAderived compounds but also shows some drawbacks of these compounds, such low bioavailability and/or poor solubility of several derivatives of DA. It focusses on the chemical aspects and summarizes the DA related biological effects without deep discussion of underlying biochemical pathways.

CONCLUSION

Dehydroabietylamine-derived cytotoxic compounds hold a high potential to be developed into efficient antitumor active drugs.

Syntheses and medicinal chemistry of azepinoindolones: a look back to leap forward

Nitrogen-containing heterocyclic scaffolds constitute nearly 75% of small molecules which favorably act as drug candidates. For the past few decades, numerous natural and synthetic indole-based scaffolds have been reported for their diverse pharmacological profiles. In particular, indole-fused azepines, termed azepinoindolones, have come under the radar of medicinal chemists owing to their synthetic and pharmacological importance. A plethora of literature reports has been generated thereof, which calls for the need for the compilation of information to understand their current status in drug discovery. Accumulating reports of evidence suggest that compounds containing this privileged scaffold display their cytotoxic effects via inhibition of kinase, topoisomerase I, mitochondrial malate dehydrogenase (mMDH), and tubulin polymerization and as DNA minor groove binding agents. Herein, we endeavor to present a closer look at the advancements of various synthetic and derivatization methods of azepinoindolone-based compounds. We have further extended our efforts to discuss the pharmacological effects of azepinoindolones in the whole range of medicinal chemistry as anti-Alzheimer, anticancer, anti-inflammatory, antidiabetic, antileishmanial, and antipyranosomal agents and as drug delivery vectors. Our analysis of recent advances reveals that azepinoindolones will continue to serve as potential pharmaceutical modalities in the years to come and their substantial pool of synthetic methods will be ever expanding.

First catalyst-free CO2 trapping of N-acyliminium ions under ambient conditions: sustainable multicomponent synthesis of thia- and oxazolidinyl carbamates

The first trapping of N-acyliminium ions by in situ generated carbaminic acid (product of carbon dioxide (CO2) and amine) is reported. This catalyst-free reaction provides a convenient and feasible approach to prepare N-acyl thia- and oxazolidinyl carbamates with good functional-group compatibility and high efficiency under green conditions. Furthermore, the multicomponent method features a broad substrate scope, facile product diversification, smooth scale-up and notable potential for polymer applications.

Synthesis of pretubulysin-derivatives via the TubUgi-approach

The Ugi reaction is found to be a very powerful tool for the synthesis of (pre)tubulysin derivatives, allowing the introduction of various functionalized side chains in only one step. While polar groups such as amides are not well tolerated, unpolar side chains such as allyl or propargyl ether are well accepted. These functionalities also allow subsequent modifications in the side chain, e.g. via ring closing metathesis or Click reaction.

AuCu and AgCu bimetallic nanoparticles supported on guanidine-modified reduced graphene oxide nanosheets as catalysts in the reduction of nitroarenes: tandem synthesis of benzo[b][1,4]diazepine derivatives

AuCu and AgCu bimetallic nanoparticles supported on guanidine-grafted reduced graphene oxide nanosheets as reduction catalysts.

Sources for Leads: Natural Products and Libraries

Natural products have traditionally been a major source of leads in the drug discovery process. However, the development of high-throughput screening led to an increased interest in synthetic methods that enabled the rapid construction of large libraries of molecules. This resulted in the termination or downscaling of many natural product research programs, but the chemical libraries did not necessarily produce a larger amount of drug leads. On one hand, this chapter explores the current state of natural product research within the drug discovery process. On the other hand it evaluates the efforts made to increase the amount of leads generated from chemical libraries and considers what role natural products could play here.

CeCl₃.7H2O/NaI-promoted direct synthesis of 1,3-benzoxazine-2-thione n-nucleosides under microwave irradiation

A microwave-assisted efficient and direct synthetic route to 1,3-benzoxazine-2-thione N-nucleos ides via CeCl₃.7H2O/NaI catalyzed cycloisomerization of salicylaldehyde 4-(β-D-ribofuranosyl) thiosemicarbazones followed by reductive dehydrazination is reported.

One-pot oxidative Ugi-type three-component reaction of aromatic hydrocarbons of petroleum naphtha: comparing catalytic effect of cellulose- and wool–SO3H supported with manganese dioxide nanostructures

A novel domino oxidative Ugi-type three-component reaction (OU-3CR) of aromatic hydrocarbons of petroleum naphtha has been investigated using two biopolymer supported MnO₂ nanostructured catalysts, MnO₂@cellulose–SO₃H and MnO₂@wool–SO₃H.

ZnS nanoparticles as an efficient recyclable heterogeneous catalyst for one-pot synthesis of 4-substituted-1,5-benzodiazepines

An efficient and novel method was developed for the synthesis of 4-substituted-1,5-benzodiazepine derivatives via a one-pot three-component catalytic reaction.

Diastereoselective synthesis of fused [1,3]thiazolo[1,3]oxazins and [1,3]oxazino[2,3-b][1,3]benzothiazoles

An efficient diastereoselective synthesis of 7-ethyl 5,6-dialkyl 7H-[1,3]thiazolo[2,3-b][1,3]oxazin-5,6, 7-tricarboxylates and 2-ethyl 3,4-dialkyl 2H-[1,3]oxazino [2,3-b][1,3]benzothiazole-2,3,4-tricarboxylates via reaction of thiazole and benzothiazole with dialkyl acetylenedicarboxylates in the presence of ethyl pyruvate is described.

In Situ Generation of ChiralN-Dienyl Lactams in a Multicomponent Reaction: An Efficient and Highly Selective Way to Asymmetric Amidocyclohexenes

Chiral N-dienyl lactams are crucial building blocks for the synthesis of complex organic compounds. However, their generation is rather challenging. This paper reports on a highly efficient and diastereoselective multicomponent methodology utilizing chiral amides, aldehydes, and dienophiles (AAD reaction). The three components readily react under in situ generation of chiral N-dienyl lactams which undergo a subsequent Diels-Alder reaction. Different chiral amides have been employed in the standard protocol delivering yields up to 94%, and selectivities up to 90% de. Moreover, DFT calculations were performed to explain the obtained selectivities.

Three-Component Reactions with (S)-Methyl Pyroglutamate: An Efficient Way to Diversely Substituted Asymmetric Amidocyclohexenes

Chiral N-dienyl lactams are crucial building blocks for the synthesis of complex organic compounds. However, their generation is rather challenging. This paper reports the novel one-pot reaction of (S)-methyl pyroglutamate as the amide component with different aldehydes and dienophiles (AAD reaction) to give novel chiral 1-amido-2-cyclohexenes. The corresponding N-dienyl lactams generated in situ undergo subsequent Diels-Alder reactions in good yield and diastereoselectivity. The scope and limitations of the three-component protocol were investigated. X-ray and NMR spectroscopic analysis of the products as well as DFT calculations of the intermediates were also performed to explain the observed stereoselectivity and structural features.