The DARK Side of Total Synthesis: Strategies and Tactics in Psychoactive Drug Production

Enantioselective de novo synthesis of 14-hydroxy-6-oxomorphinans

The enantioselective de novo synthesis of pharmacologically important 14-hydroxy-6-oxomorphinans is described. 4,5-Desoxynaltrexone and 4,5-desoxynaloxone were prepared using this route and their biological activities against the opioid receptors were measured.

Increased incidence of mixed drug toxicity deaths involving tapentadol - A forensic study

Tapentadol is a relatively new synthetic opioid analgesic prescribed for the management of moderate to severe pain. While tapentadol has been shown to be more effective than traditional opioid analgesics, it still carries the risk of addiction, abuse, and misuse. In Australia, tapentadol has become one of the top five most commonly prescribed opioid drugs, with prescriptions increasing by approximately 150,000 each year since it first became available. The rapid increase in tapentadol prescriptions has occurred in parallel to an increasing number of post-mortem tapentadol detections in South Australia (SA). While the number of deaths in SA related to tapentadol use was low in the current study, findings suggest that an increasing trend of deaths involving tapentadol will continue in parallel to a rapidly increasing number of prescriptions, mirroring trends associated with traditional opioids in SA. As a comparatively new opioid analgesic, monitoring future trends will be important to determine if additional prescribing education, intervention, or restrictions are required.

New Psychoactive Substances: Major Groups, Laboratory Testing Challenges, Public Health Concerns, and Community-Based Solutions

Across communities worldwide, various new psychoactive substances (NPSs) continue to emerge, which worsens the challenges to global mental health, drug rules, and public health risks, as well as combats their usage. Specifically, the vast number of NPSs that are currently available, coupled with the rate at which new ones emerge worldwide, increasingly challenges both forensic and clinical testing strategies. The well-established NPS detection techniques include immunoassays, colorimetric tests, mass spectrometric techniques, chromatographic techniques, and hyphenated types. Nonetheless, mitigating drug abuse and NPS usage is achievable through extensive community-based initiatives, with increased focus on harm reduction. Clinically validated and reliable testing of NPS from human samples, along with community-driven solution, such as harm reduction, will be of great importance, especially in combating their prevalence and the use of other illicit synthetic substances. There is a need for continued literature synthesis to reiterate the importance of NPS, given the continuous emergence of illicit substances in the recent years. All these are discussed in this overview, as we performed another look into NPS, from differentiating the major groups and identifying with laboratory testing challenges to community-based initiatives.

Continuous-Flow Chemistry and Photochemistry for Manufacturing of Active Pharmaceutical Ingredients

An active pharmaceutical ingredient (API) is any substance in a pharmaceutical product that is biologically active. That means the specific molecular entity is capable of achieving a defined biological effect on the target. These ingredients need to meet very strict limits; chemical and optical purity are considered to be the most important ones. A continuous-flow synthetic methodology which utilizes a continuously flowing stream of reactive fluids can be easily combined with photochemistry, which works with the chemical effects of light. These methods can be useful tools to meet these strict limits. Both of these methods are unique and powerful tools for the preparation of natural products or active pharmaceutical ingredients and their precursors with high structural complexity under mild conditions. This review shows some main directions in the field of active pharmaceutical ingredients' preparation using continuous-flow chemistry and photochemistry with numerous examples of industry and laboratory-scale applications.

Microwave-Aided Reactions of Aniline Derivatives with Formic Acid: Inquiry-Based Learning Experiments

The synthesis of amides belongs to traditional experimental tasks not only in organic chemistry exercises at universities but also at chemically focused secondary schools or in special practices at general high schools. An example of such a synthesis may be the preparation of acetanilide via reaction of aniline with acetic acid or acetic anhydride. However, both of these reactions are associated with a rather long reaction time and certain hazards that limit their straightforward use in pedagogical practice. Conveniently, the reaction of aniline with acetic acid may be significantly optimised if it is performed under solvent-free conditions in the presence of microwaves, which reduces considerably the reaction time and provides very good yield, compared to traditional heating by a heating nest. In this study, the main pedagogical aim of the experimental design is elucidation of the influence of the structure of the amines on the course of the reaction with formic acid through inquiry-based learning. Specifically, the proposed experiments consist in investigation of the chemical yield achieved in microwave assisted reactions of aniline and its derivatives with formic acid in such a way that is adequate for constructive learning of undergraduate chemistry students. The selected series of amines involves aniline, 4-methoxyaniline, 4-chloroaniline, and 4-nitroaniline. In accordance with the chemical reactivity principles, students gradually realise that the influence of the substituent is reflected in the reaction yield, which grows in the following order: N-(4-nitrophenyl)formamide ˂ N-(4-chlorophenyl)formamide ˂ N-phenylformamide ˂ N-(4-methoxyphenyl)formamide. Therefore, the results of the experiments enable students to discover that stronger basicity of the amine increases the yield of the amide. In order to deepen the students’ chemical knowledge and skills, the concept of the experiments was transformed to support inquiry-based student learning. The proposed experiments are intended for experimental learning in universities educating future chemistry teachers, but they may be also utilised in the form of workshops for students at secondary schools of a general educational nature.

Structure identification and analysis of the suspected chemical precursor of 2-fluorodeschloroketamine and its decomposition products

In this work, 1-[(2"-fluorophenyl)(methylimino) methyl]cyclopentan-1-ol (2-fluorodeschlorohydroxylimine) was identified as a suspected chemical precursor of 2-fluorodeschloroketamine (2-FDCK) using GC-MS and GC-Q/TOF-MS and comparing the data with those of ketamine and its chemical precursor, hydroxylimine. Furthermore, the entire fragmentation pathway of 2-fluorodeschlorohydroxylimine was theorized from the GC-MS spectrum recorded using an electron ionization (EI) source, and the mechanisms and decomposition pathways of 2-fluorodeschlorohydroxylimine were elucidated. In protic solvents, the nitrogen atom in the C=N group of 2-fluorodeschlorohydroxylimine underwent a protonation reaction. Thereafter, the traces of water present in protic solvents promoted the hydrolysis of the protonated imine, and a carbon cation was obtained following the loss of methylamine. The carbon cation could follow the classical decomposition mechanism of imines and yield an α-hydroxyl ketone, which was the major decomposition product, (2'-fluorophenyl)(1"-hydroxycyclopentyl) methanone. The cation could also undergo a loop expansion rearrangement and yield another α-hydroxyl ketone, 2-(2'-fluorophenyl)-2-hydroxycyclohexan-1-one. The structures of the two aforementioned decomposition products were elucidated using several techniques including theoretical calculation, GC-MS, NMR, the prediction and assistance elucidation functions of ACDLabs-Structure Elucidator Suite, and the virtual separation technology of diffusion-ordered spectroscopy. The aforementioned study revealed important information about the chemical precursor of 2-FDCK and its decomposition. Furthermore, a set of methods for the qualitative analysis of 2-fluorodeschlorohydroxylimine was established, which facilitated accurate analysis of 2-fluorodeschlorohydroxylimine samples following decomposition or destruction.

Fully Validated, Multi-Kilogram cGMP Synthesis of MDMA

MDMA is increasingly used in clinical research, but no cGMP process has yet been reported. We describe here the first fully validated cGMP synthesis of up to 5 kg (≈30 000 patient doses) of MDMA in a four-step process beginning with a noncontrolled starting material. The overall yield was acceptable (41-53%, over four steps), and the chemical purity of the final product was excellent, exceeding 99.9% of the peak area by HPLC in each of the four validation trials. The availability of cGMP-compliant MDMA will facilitate ongoing clinical trials and provide for future therapeutic use, if encouraging results lead to FDA approval.

A brief overview of classical natural product drug synthesis and bioactivity

This manuscript briefly overviewed the total synthesis and structure–activity relationship studies of eight classical natural products, which emphasizes the important role of total synthesis in natural product-based drug development.

Morphine alkaloids: History, biology, and synthesis

This chapter provides a short overview of the history of morphine since it's isolation by Sertürner in 1805. The biosynthesis of the title alkaloid as well as all total and formal syntheses of morphine and codeine published after 1996 are discussed in detail. The last section of this chapter provides a detailed overview of medicinally relevant derivatives of the title alkaloid.

Deconstructive Asymmetric Total Synthesis of Morphine-Family Alkaloid (-)-Thebainone A

Herein, we describe the development of a deconstructive strategy for the first asymmetric synthesis of (-)-thebainone A, capitalizing on an enantioselective C-C bond activation and a C-O bond cleavage reaction. The rhodium-catalyzed asymmetric "cut-and-sew" transformation between sterically hindered trisubstituted alkenes and benzocyclobutenones allowed efficient construction of the fused A/B/C rings and the quaternary center of the natural product. The newly optimized conditions show broad substrate scope and excellent enantioselectivity (up to 99.5:0.5 er). Taking advantage of boron-mediated ether bond cleavage, we completed the synthesis of the morphine alkaloid (-)-thebainone A by two complementary routes.

DARK Classics in Chemical Neuroscience: Heroin and Desomorphine

Opioids are arguably one of the most important pharmacologic classes, mainly due to their rich history, their useful and potent analgesic effects, and also, just as importantly, their "Dark Side", constituted by their reinforcing properties that have led countless of users to a spiral of addiction, biological dependence, tolerance, withdrawal syndromes, and death. Among the most significant abused and addictive known opioids are heroin and desomorphine, both synthetic derivatives of morphine that belong to the 4,5-epoxymorphinan structural chemical group of the opioid family drugs. These agents share not only structural, pharmacological, and epidemiological features but also a common geographical distribution. A drop in Afghan heroin production and its "exports" to Russia gave rise to widespread consumption of desomorphine in ex-Soviet republics during the first decade of the 21st century, representing an economical and accessible alternative for misusers to this sort of derivative. Herein we review the state of the art of history, chemistry and synthesis, pharmacology, and impact on society of these "cursed cousins".

Interpol review of controlled substances 2016-2019

This review paper covers the forensic-relevant literature in controlled substances from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20Papers%202019.pdf.

Total Synthesis of (±)-Thebainone A by Intramolecular Nitrone Cycloaddition

Using an intramolecular nitrone cycloaddition and a Heck cyclization as the crucial transformations, a total synthesis of the racemic morphine alkaloid thebainone A was accomplished in 22 steps commencing with isovanillin.

Evolution of flow-oriented design strategies in the continuous preparation of pharmaceuticals

This review focuses on the flow-oriented design (FOD) in the multi-step continuous-flow synthesis of active pharmaceutical ingredients.

Transition-metal-free α-arylation of nitroketones with diaryliodonium salts for the synthesis of tertiary α-aryl, α-nitro ketones

Transition-metal-free α-arylation of α-nitroketones with diaryliodonium salts has been developed for the first time and applied in the synthesis of tiletamine.

DARK Classics in Chemical Neuroscience: Methamphetamine

Methamphetamine has the second highest prevalence of drug abuse after cannabis, with estimates of 35 million users worldwide. The ( S)-(+)-enantiomer is the illicit drug, active neurostimulant, and eutomer, while the ( R)-(-)-enantiomer is contained in over the counter decongestants. While designated a schedule II drug in 1970, ( S)-(+)-methamphetamine is available by prescription for the treatment of attention-deficit disorder and obesity. The illicit use of ( S)-(+)-methamphetamine results in the sudden "rush" of stimulation to the motivation, movement, pleasure, and reward centers in the brain, caused by rapid release of dopamine. In this review, we will provide an overview of the synthesis, pharmacology, adverse effects, and drug metabolism of this widely abused psychostimulant that distinguish it as a DARK classic in Chemical Neuroscience.