Flow chemistry is a continually emerging and ever-growing area of synthetic organic chemistry. It provides an orthogonal approach to traditional batch chemistry, oftentimes allowing for more efficient routes to desired target molecules. It is generally accepted that flow chemistry offers a valuable change to the process landscape. From a process perspective, there are many advantages associated with flow chemistry over traditional batch chemistry, the most prominent of which is an increased safety profile with the use of highly reactive chemical species, such as organolithiums. These reagents are highly valuable species for the efficient synthesis of pharmaceutical intermediates. Disadvantageously, use of these reagents on commercial scale is severely hindered by the highly energetic nature of the reaction intermediates and their concomitant safety risk. Flow chemistry provides a viable platform for use of these reagents, offering a high degree of control over reaction parameters. In this review, we present a comprehensive account of the published literature implementing the use of organolithium reagents as strong bases for deprotonation reactions in flow systems.

We present a study of a range of cross-linked chitosan composites with potential antimicrobial applications. They were formed by cross-linking chitosan and siloxane networks and by introducing silver and gold nanoparticles (NPs). The aim was to investigate whether adding the metal NPs to the chitosan-siloxane composite would lead to a material with enhanced antimicrobial ability as compared to chitosan itself. The composites were synthesised in hydrogel form with the metal NPs embedded in the cross-linked chitosan network. Spectroscopic and microscopic techniques were employed to investigate the structural properties of the composite and the tensile strength of the structures was measured. It was found that the addition of metal NPs did not influence the mechanical strength of the composite. A crystal violet attachment assay results displayed a significant reduction in the attachment of E. coli to the cross-linked chitosan surfaces. Release profile tests suggest that the metal NPs do not contribute to the overall antimicrobial activity under neutral conditions. The contribution to the mechanical and antimicrobial properties from cross-linking with siloxane is significant, giving rise to a versatile, durable, antimicrobial material suitable for thin film formation, wound dressings or the coating of various surfaces where robustness and antimicrobial control are required.

Density functional theory computations have elucidated the mechanism and origins of stereoselectivity in McGlacken’s aldol-Tishchenko reaction for the diastereoselective synthesis of 1,3-amino alcohols using Ellman’s t -butylsulfinimines as chiral auxiliaries. Variations of stereochemical outcome are dependent on the nature of the ketone starting materials used, and the aspects leading to these differences have been rationalized. The intramolecular hydride transfer step is the rate- and stereochemistry-determining step, and all prior steps are reversible.

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A continuous flow methodology is described which gives α-alkylated ketones in good yields, avoids cryogenic temperatures, excessive exposure to alkyllithiums/alkylhalides, and can be easily and continuously scaled-out (to >3 g in 45 min).