A ruthenium-carbamato-complex derived from a siloxylated amine and carbon dioxide for the oxidative α-cyanation of aromatic and cyclic tertiary amines

A number of synthetic cathinones (aminoketones, 'bath salts') are tertiary amines containing a cyclic amino group, most commonly pyrrolidine. These totally synthetic compounds can be prepared in a number of regioisomeric designer modifications and many of these can yield isomeric major fragment ions in electron ionization mass spectrometry (EI-MS). A series of regioisomeric cyclic tertiary amines were prepared and evaluated in EI-MS and MS/MS product ion experiments. The cyclic amines azetidine, pyrrolidine, piperidine and azepane were incorporated into a series of aminoketones related to the cathinone derivative drug of abuse known as MDPV. Deuterium labeling in both the cyclic amine and alkyl side chain allowed for the confirmation of the structure for the major product ions formed from the EI-MS iminium cation base peaks. These iminium cation base peaks show characteristic product ion spectra which allow differentiation of the ring and side-chain portions of the structure. The small alkyl side chains favor ring fragmentation in the formation of the major product ions. The higher side-chain homologues appear to promote product ion formation by side-chain fragmentation. Both side-chain and ring fragmentation yield a mixture of product ions in the piperidine and azepane series. Product ion fragmentation provides useful data for differentiation of cyclic tertiary amine iminium cations from cathinone derivative drugs of abuse. Regioisomeric iminium cations of equal mass yield characteristic product ions for the alkyl side-chain homologues of azetidine, pyrrolidine, piperidine and azepane cyclic amines.

An intriguing C-N transformation involving a catalyst-free N-alkylation/N'-arylation process in a multicomponent reaction with secondary amines, cyclic tertiary amines and electron-deficient aryl halides has been described. In this case, the N-alkylation of secondary amines, utilizing cyclic tertiary amines as alkyl group sources, is enabled by a facile C-N cleavage. Such an operationally simple method could facilitate access to aromatic aminoalkyl amines, nitrogen-containing bioactive molecules, in good to excellent yields.

Cathepsin D, a lysosomal aspartic protease, has been suggested to play a role in the metastatic potential of several types of cancer. A high activated cathepsin D level in breast tumor tissue has been associated with an increased incidence of relapse and metastasis. High levels of active cathepsin D have also been found in colon cancer, prostate cancer, uterine cancer and ovarian cancer. Hydroxyethyl isosteres with cyclic tertiary amine have proven to be clinically useful as inhibitors of aspartyl proteases similar to cathepsin D in activity, such as the HIV-1 aspartyl protease. The design and the synthesis of (hydroxyethyl)amine isostere inhibitors with cyclic tertiary amines is described. The IC50 and Ki (app) values for the six cathepsin D inhibitors and pepstatin are reported. Compounds 7b,3(S)-[Acetyl-L-valyl-L-phenylalanylamino]-4-phenyl-1-N-piperidine-2(S)-butanol,and 7c, 3(S)-[Acetyl-L-leucyl-L-phenylalanylamino]-4-phenyl-1-N-piperidine-2(S)-butanol, showed the most potent inhibition of cathepsin D hydrolysis of hemoglobin with IC50 values of 3.5 nM and 4.5 nM, respectively.

A novel and catalyst‐free multicomponent reaction with cyclic tertiary amines, electron‐deficient aryl halides or heteroaromatic halides, and Na2S enabled by facile C−N bond cleavage of the cyclic tertiary amines was developed. This direct and operationally simple method can be applied with a wide range of functional groups and provides an efficient and rapid approach to potentially drug‐like products containing amine, azaarene, thioether, or phenol ether functionalities in good to excellent yields. The utility of this method was demonstrated by the rapid synthesis of the analgesic ruzadolane.

A novel and catalyst-free multicomponent reaction with cyclic tertiary amines, electron-deficient aryl halides or heteroaromatic halides, and Na2 S enabled by facile C-N bond cleavage of the cyclic tertiary amines was developed. This direct and operationally simple method can be applied with a wide range of functional groups and provides an efficient and rapid approach to potentially drug-like products containing amine, azaarene, thioether, or phenol ether functionalities in good to excellent yields. The utility of this method was demonstrated by the rapid synthesis of the analgesic ruzadolane.

Opening the ring of cyclic amines by regioselective fission of one of the carbon-nitrogen bonds greatly expands the repertoire of available nitrogen-containing skeletons. Unlike approaches starting from cyclic tertiary amines, methods that can directly open secondary amines are still scarce. The present work discloses an efficient reductive ring opening of either of these cyclic amines using PhSiH3 under B(C6 F5 )3 catalysis. By this, the direct transformation of unstrained cyclic amines into the corresponding acyclic amines is achieved in a simple one-pot operation. A stepwise mechanism proceeding through the intermediacy of silylammonium ions followed by reductive cleavage of a carbon-nitrogen bond was experimentally verified.

Lipid nanoparticles (LNPs) have become an important platform for nucleic acid delivery. However, LNP-mediated delivery to non-hepatic organs and specific cell types remains a non-negligible challenge. As a key component of LNPs, ionizable lipids were rationally designed to adjust the LNPs properties to achieve organ-targeted delivery. The use of the Ugi four-component reaction (Ugi-4CR) as a one-pot multicomponent synthesis strategy to construct ionizable lipid molecules offers advantages, as it enables multidimensional structural diversity of ionizable lipids. We use isocyanides with cyclic tertiary amine substituents to construct ionizable lipids via an Ugi one-pot reaction. Twenty-five ionizable lipid molecules (W1-W25) containing different cyclic tertiary amine hydrophilic heads, linkers, and hydrophobic tails were synthesized. The W19 LNPs exhibited highly selective mRNA delivery to the spleen upon intravenous administration.

Cytochrome P450-mediated bioactivation of drugs to reactive metabolites has been reported to be the first step in many adverse drug reactions. Metabolic activation of cyclic tertiary amines often generates a number of oxidative products including N-dealkylation, ring hydroxylation, α-carbonyl formation, N-oxygenation, and ring opening metabolites that can be formed through iminium ion intermediates. Therapeutic pharmaceuticals and their metabolites containing a cyclic tertiary amine structure have the potential to form iminium intermediates that are reactive toward nucleophilic macromolecules. Examples of cyclic tertiary amines that have the potential for forming reactive iminium intermediates include the piperazines, piperidines, 4-hydroxypiperidines, 4-fluoropiperidines and related compounds, pyrrolidines and N-alkyltetrahydroquinolines. Major themes explored in this review include bioactivation reactions for cyclic tertiary amines, which are responsible for the formation of iminium intermediates, together with some representative examples of drugs and guidance for discovery scientists in applying the information to minimize the bioactivation potential of cyclic amine-based compounds in drug discovery. Potential strategies to abrogate reactive iminium intermediate formation are also discussed.

A Novel Reaction of Cyanogen Iodide with Cyclic Tertiary Amines

The accessibility of large substrates to buried enzymatic active sites is dependent upon the utilization of proteinaceous channels. The necessity of these channels in the case of small substrates is questionable because diffusion through the protein matrix is often assumed. Copper amine oxidases contain a buried protein-derived quinone cofactor and a mononuclear copper center that catalyze the conversion of two substrates, primary amines and molecular oxygen, to aldehydes and hydrogen peroxide, respectively. The nature of molecular oxygen migration to the active site in the enzyme from Hansenula polymorpha is explored using a combination of kinetic, x-ray crystallographic, and computational approaches. A crystal structure of H. polymorpha amine oxidase in complex with xenon gas, which serves as an experimental probe for molecular oxygen binding sites, reveals buried regions of the enzyme suitable for transient molecular oxygen occupation. Calculated O(2) free energy maps using copper amine oxidase crystal structures in the absence of xenon correspond well with later experimentally observed xenon sites in these systems, and allow the visualization of O(2) migration routes of differing probabilities within the protein matrix. Site-directed mutagenesis designed to block individual routes has little effect on overall k(cat)/K(m) (O(2)), supporting multiple dynamic pathways for molecular oxygen to reach the active site.

Design, synthesis, in vitro antiproliferative evaluation and in silico studies of new VEGFR-2 inhibitors based on 4-piperazinylquinolin-2(1H)-one scaffold

A metal-free strategy for the formation of lactams via selective oxidation of cyclic secondary and tertiary amines is described. Molecular iodine facilitates both chemoselective and regioselective oxidation of C-H bonds directly adjacent to a cyclic amine. The mild conditions, functional group tolerance, and substrate scope are demonstrated using a suite of diverse small molecule cyclic amines, including clinically approved drug scaffolds.

Oxidation reactions are of fundamental importance in nature, and are key transformations in organic synthesis. The development of new processes that employ transition metals as substrate-selective catalysts and stoichiometric environmentally friendly oxidants, such as molecular oxygen or hydrogen peroxide, is one of the most important goals in oxidation chemistry. Direct oxidation of the catalyst by molecular oxygen or hydrogen peroxide is often kinetically unfavored. The use of coupled catalytic systems with electron-transfer mediators (ETMs) usually facilitates the procedures by transporting the electrons from the catalyst to the oxidant along a low-energy pathway, thereby increasing the efficiency of the oxidation and thus complementing the direct oxidation reactions. As a result of the similarities with biological systems, this can be dubbed a biomimetic approach.

The intramolecular Csp3–H and/or C–C bond amination is very important in modern organic synthesis due to its efficiency in the construction of diversified N-heterocycles. Herein, we report a novel intramolecular cyclization of alkyl azides for the synthesis of cyclic imines and tertiary amines through selective Csp3–H and/or C–C bond cleavage. Two C–N single bonds or a CCreated by potrace 1.16, written by Peter Selinger 2001-2019]]>N double bond are efficiently constructed in these transformations. The carbocation mechanism differs from the reported metal nitrene intermediates and therefore enables metal-free and new transformation.

Various copper(II) alkanoate adducts with cyclic ethers and tertiary amines have been prepared and characterized by means of magnetic susceptibility and IR spectroscopy measurements. The effect on the magnetic moments of the dinuclear copper(II) alkanoates of varying the base strength of the axial ligands is also discussed.