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Please cite this article as: O'Brien, M., Cooper, D.A., Dolan, J., Continuous flow iodination using an automated computer-vision controlled liquid-liquid extraction system., Tetrahedron Letters (2017), doi: http://dx.doi.org/ 10. 1016/j.tetlet.2017.01.029 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Graphical AbstractTo create your abstract, type over the instructions in the template box below. Fonts or abstract dimensions should not be changed or altered. Continuous flow iodination using an automated computer-vision controlled liquid-liquid extraction systemMatthew O'Brien,* Dennis A. Cooper and Jonathan Dolan Leave this area blank for abstract info. Staffordshire, ST5 5BG, UK. Over the last decade or so, flow chemistry has emerged as an alternative model to more traditional batch approaches to synthesis.1 In addition to offering significant safety benefits when using hazardous reagents, intermediates or conditions, 2 flow chemistry often enables superior control over interfacial exchange parameters 3 leading to highly efficient and scaleinvariant chemical processes. A particularly attractive feature of flow chemistry is the ability to incorporate in-line purification techniques. The use of solid-supported scavengers 4 and phaseswitching reagents have enabled many noteworthy flow syntheses. 5 In-line liquid-liquid extraction is also emerging as an alternative approach. Whilst it has limitations (obviously relying on efficient extraction from one phase to another) it can also offer advantages. Firstly, solid-supported reagents are often much more expensive than the equivalent soluble form. 6 Secondly, unless some regeneration protocol is incorporated into the system, solid-supported reagents become depleted over time and at some point will need replacing, possibly requiring the system to be temporarily shut down. Liquid extractants, which can be pumped continuously into the system, do not suffer from this issue. The use of solid supports also causes significant scaledependent dispersive effects.7 Whilst there will also be unavoidable dispersive effects associated with liquid-liquid extraction processes these can, in principle, be rendered scaleinvariant. Semi-permeable hydrophobic membranes, particularly those based on expanded PTFE, 8 have been used to effect continuous flow separation of aqueous and organic flow streams. 9 An alternative approach, essentially a flow adaptation of the traditional separating funnel, relies on the vertical separation of immiscible liquids under gravity. If a flow stream containing a mixture of two immiscible liquids is fed into a separating vessel with ...

While the field of biocatalysis has bloomed over the past 20−30 years, advances in the understanding and improvement of carbohydrate-active enzymes, in particular, the sugar nucleotides involved in glycan building block biosynthesis, have progressed relatively more slowly. This perspective highlights the need for further insight into substrate promiscuity and the use of biocatalysis fundamentals (rational design, directed evolution, immobilization) to expand substrate scopes toward such carbohydrate building block syntheses and/or to improve enzyme stability, kinetics, or turnover. Further, it explores the growing premise of using biocatalysis to provide simple, cost-effective access to stereochemically defined carbohydrate materials, which can undergo late-stage chemical functionalization or automated glycan synthesis/polymerization.

The chemoenzymatic synthesis of a series of dual N- and C-terminal–functionalized cholera toxin B subunit (CTB) glycoconjugates is described. Mucin 1 peptides bearing different levels of Tn antigen glycosylation [MUC1(Tn)] were prepared via solid-phase peptide synthesis. Using sortase-mediated ligation, the MUC1(Tn) epitopes were conjugated to the C-terminus of CTB in a well-defined manner allowing for high-density display of the MUC1(Tn) epitopes. This work explores the challenges of using sortase-mediated ligation in combination with glycopeptides and the practical considerations to obtain high levels of conjugation. Furthermore, we describe methods to combine two orthogonal labeling methodologies, oxime- and sortase-mediated ligation, to expand the biochemical toolkit and produce dual N- and C-terminal–labeled conjugates.

Post-translational glycosylation of proteins results in complex mixtures of heterogeneous protein glycoforms. Glycoproteins have many potential applications from fundamental studies of glycobiology to potential therapeutics, but generating homogeneous recombinant glycoproteins using chemical or chemoenzymatic reactions to mimic natural glycoproteins or creating homogeneous synthetic neoglycoproteins is a challenging synthetic task. In this work, we use a site-specific bioorthogonal approach to produce synthetic homogeneous glycoproteins. We develop a bifunctional, bioorthogonal linker that combines oxime ligation and strain-promoted azide–alkyne cycloaddition chemistry to functionalize reducing sugars and glycan derivatives for attachment to proteins. We demonstrate the utility of this minimal length linker by producing neoglycoprotein inhibitors of cholera toxin in which derivatives of the disaccharide lactose and GM1os pentasaccharide are attached to a nonbinding variant of the cholera toxin B-subunit that acts as a size- and valency-matched multivalent scaffold. The resulting neoglycoproteins decorated with GM1 ligands inhibit cholera toxin B-subunit adhesion with a picomolar IC 50 .