Process Intensification for Obtaining a Cannabidiol Intermediate by Photo-oxygenation of Limonene under Continuous-Flow Conditions

Batch and Continuous Flow Total Synthesis of Cannabidiol

Herein, we present a comprehensive total synthesis of cannabidiol integrating both batch and continuous flow conditions. Our approach is planned to streamline the synthesis of olivetolic acid derivatives and utilize an enantiomerically pure monoterpene moiety obtained from naturally occurring (R)-(+)-limonene by photocatalysis. Key reactions, including the synthesis of olivetolic ester and a Friedel-Crafts alkylation, are successfully adapted to continuous flow, resulting in improved yields and selectivities. This study not only offers a scalable and efficient route for cannabidiol synthesis but also contributes to the synthetic approaches to access cannabinoids (diversity synthesis), with potential applications in medicinal and industrial contexts.

Essential Oils: Chemistry and Pharmacological Activities-Part II

The importance of essential oils and their components in the industrial sector is attributed to their chemical characteristics and their application in the development of products in the areas of cosmetology, food, and pharmaceuticals. However, the pharmacological properties of this class of natural products have been extensively investigated and indicate their applicability for obtaining new drugs. Therefore, this review discusses the use of these oils as starting materials to synthesize more complex molecules and products with greater commercial value and clinic potential. Furthermore, the antiulcer, cardiovascular, and antidiabetic mechanisms of action are discussed. The main mechanistic aspects of the chemopreventive properties of oils against cancer are also presented. The data highlight essential oils and their derivatives as a strategic chemical group in the search for effective therapeutic agents against various diseases.

Continuous flow reactions in the preparation of active pharmaceutical ingredients and fine chemicals

Herein, we present an overview of continuous flow chemistry, including photoflow and electroflow technologies in the preparation of active pharmaceutical ingredients (APIs) and fine chemical intermediates. Examples highlighting the benefits and challenges associated with continuous flow processes, mainly involving continuous thermal, photo- and electrochemical transformations, are drawn from the relevant literature, especially our experience and collaborations in this area, with emphasis on the synthesis and prospective scale-up.

Scaled up and telescoped synthesis of propofol under continuous-flow conditions

Herein we report a machine-assisted and scaled-up synthesis of propofol, a short-acting drug used in procedural sedation, which is extensively in demand during this COVID-19 pandemic. The continuous-flow protocol proved to be efficient, with great potential for industrial translation, reaching a production up to 71.6 g per day with process intensification (24 h-continuous experiments). We have successfully telescoped a continuous flow approach obtaining 5.74 g of propofol with productivity of 23.0 g/day (6 h-continuous experiment), proving the robustness of the method in both separated and telescoped modes. Substantial progress was also achieved for the in-line workup, which provides greater safety and less waste, also relevant for industrial application. Overall, the synthetic strategy is based on the Friedel-Crafts di-isopropylation of low-cost p-hydroxybenzoic acid, followed by a decarboxylation reaction, giving propofol in up to 84% overall yield and very low by-product formation. The continuous flow synthesis of propofol 3 is presented as a two-step protocol. The isopropylated intermediate 2 was obtained from 4-hydroxybenzoic acid (1) in up 43.8 g, 85% yield and 30 min residence time. Propofol 3 was then obtained in 71.6 g, 87% yield, and 16 min residence time. A safe and cost-competitive machine-assisted protocol is described with a process intensification demonstration (24 h experiments) and a telescoped process intensification (6 h).

Technological Innovations in Photochemistry for Organic Synthesis: Flow Chemistry, High-Throughput Experimentation, Scale-up, and Photoelectrochemistry

Photoinduced chemical transformations have received in recent years a tremendous amount of attention, providing a plethora of opportunities to synthetic organic chemists. However, performing a photochemical transformation can be quite a challenge because of various issues related to the delivery of photons. These challenges have barred the widespread adoption of photochemical steps in the chemical industry. However, in the past decade, several technological innovations have led to more reproducible, selective, and scalable photoinduced reactions. Herein, we provide a comprehensive overview of these exciting technological advances, including flow chemistry, high-throughput experimentation, reactor design and scale-up, and the combination of photo- and electro-chemistry.

Continuous flow technology-a tool for safer oxidation chemistry

The advantages and benefits of continuous flow technology for oxidation chemistry have been illustrated in tube reactors, micro-channel reactors, tube-in-tube reactors and micro-packed bed reactors in the presence of various oxidants.

Cannabidiol Discovery and Synthesis-a Target-Oriented Analysis in Drug Production Processes

The current state of evidence and recommendations for cannabidiol (CBD) and its health effects change the legal landscape and aim to destigmatize its phytotherapeutic research. Recently, some countries have included CBD as an antiepileptic product for compassionate use in children with refractory epilepsy. The growing demand for CBD has led to the need for high-purity cannabinoids on the emerging market. The discovery and development of approaches toward CBD synthesis have arisen from the successful extraction of Cannabis plants for cannabinoid fermentation in brewer's yeast. To understand different contributions to the design and enhancement of the synthesis of CBD and its key intermediates, a detailed analysis of the history behind cannabinoid compounds and their optimization is provided herein.