Flow chemistry involves the use of channels or tubing to conduct a reaction in a continuous stream rather than in a flask Flow equipment provides chemists with unique control over reaction parameters enhancing reactivity or in some cases enabling new reactions This relatively young technology has received a remarkable amount of attention in the past decade with many reports on what can be done in flow Until recently, however, the question, “Should we do this in flow?” has merely been an afterthought This review introduces readers to the basic principles and fundamentals of flow chemistry and critically discusses recent flow chemistry accounts

The Hitchhiker's Guide to Flow Chemistry

The catalytic formation of cyclic organic carbonates (COCs) using carbon dioxide (CO2) as a renewable carbon feed stock is a highly vibrant area of research with an increasing amount of researchers focusing on this thematic investigation. These organic carbonates are highly useful building blocks and nontoxic reagents and are most commonly derived from CO2 coupling reactions with oxirane and dialcohol precursors using homogeneous catalysis methodologies. The activation of suitable reaction partners using catalysis as a key technology is a requisite for efficient CO2 conversion as its high kinetic stability poses a barrier to access functional organic molecules with added value in both academic and industrial laboratories. Although this area of science has been flourishing for at least a decade, in the past 2–3 years, significant advancements have been made to address the general reactivity and selectivity issues that are associated with the formation of COCs. Here, we present a concise overview of these a...

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Recent advances in the catalytic preparation of cyclic organic carbonates

Efficient, selective and sustainable catalysis of carbon dioxide

http://pubs.acs.org/doi/pdf/10.1021/acs.oprd.5b00325

Flow Chemistry: Recent Developments in the Synthesis of Pharmaceutical Products

Sustainable conversion of carbon dioxide: the advent of organocatalysis

https://www.rsc.org/suppdata/gc/c3/c3gc41919c/c3gc41919c.pdf

Conversion of oxiranes and CO2 to organic cyclic carbonates using a recyclable, bifunctional polystyrene-supported organocatalyst

A polystyrene (PS)-supported 9-amino(9-deoxy)epi quinine derivative catalyzes Michael reactions affording excellent levels of conversion and enantioselectivity using different nucleophiles and structurally diverse enones. The highly recyclable, immobilized catalyst has been used to implement a single-pass, continuous flow process (residence time: 40 min) that can be operated for 21 hours without significant decrease in conversion and with improved enantioselectivity with respect to batch operation. The flow process has also been used for the sequential preparation of a small library of enantioenriched Michael adducts.

/pdf/a-polystyrene-supported-9-amino-9-deoxy-epi-quinine-2ur5uoqb4g.pdf

A polystyrene-supported 9-amino(9-deoxy)epi quinine derivative for continuous flow asymmetric Michael reactions

The preparation through Robinson annulation of enantiopure building blocks with both academic and industrial relevance, such as the Wieland–Miescher and Hajos–Parrish ketones, has suffered from important drawbacks, such as the need for high catalyst loading or extremely long reaction times. Here we report a heterogenized organocatalyst based on Luo’s diamine for fast and broad-scope enantioselective Robinson annulation reactions. The polystyrene-supported diamine 19a enables the high-yield, highly enantioselective preparation of a wide range of chiral bicyclic enones under mild conditions, with reaction times as short as 60 min (batch) or residence times of 10 min (flow). In contrast with its homogeneous counterpart 19b, the catalytic resin 19a experiences a notable increase in catalytic activity with temperature in 2-MeTHF (a 10-fold decrease in reaction times without erosion in enantioselectivity is observed from room temperature to 55 °C). The scope of the transformation in batch mode has been illustra...

/pdf/a-highly-active-polymer-supported-catalyst-for-asymmetric-1z8caalx8f.pdf

A Highly Active Polymer-Supported Catalyst for Asymmetric Robinson Annulations in Continuous Flow

A series of primary amino acid-derived polystyrene-supported organocatalysts was tested in anti-selective Mannich reactions. The polystyrene-immobilized threonine derivative showed the best performance in three-component (hydroxyacetone, anilines, and aldehydes) Mannich reactions to provide anti-β-amino-α-hydroxycarbonyl compounds (11 examples; up to 95% ee), and its use could be extended to dihydroxyacetone and protected hydroxyacetones (7 examples; up to 90% ee). The high activity depicted by the catalyst has allowed its implementation in continuous flow. Under this operation mode, the supported threonine catalyst produces anti-Mannich adducts with generally higher diastereo- and enantioselectivity than in batch. A family of five different enantioenriched anti-Mannich adducts has been sequentially prepared in flow by passing different combinations of anilines and aromatic aldehydes over the same sample of catalyst. This confirms the suitability of this methodology for the rapid access to small libraries...

/pdf/continuous-flow-enantioselective-three-component-anti-5cut34awhr.pdf

Continuous Flow Enantioselective Three-Component anti-Mannich Reactions Catalyzed by a Polymer-Supported Threonine Derivative

The polystyrene-supported catalyst can be recycled and reused for more than 5 times without a significant loss in activity and stereoselectivity.

Andrea H. Henseler

Papers

Conversion of oxiranes and CO2 to organic cyclic carbonates using a recyclable, bifunctional polystyrene-supported organocatalyst

A polystyrene-supported 9-amino(9-deoxy)epi quinine derivative for continuous flow asymmetric Michael reactions

A Highly Active Polymer-Supported Catalyst for Asymmetric Robinson Annulations in Continuous Flow

Continuous Flow Enantioselective Three-Component anti-Mannich Reactions Catalyzed by a Polymer-Supported Threonine Derivative

An Enantioselective Recyclable Polystyrene-Supported Threonine-Derived Organocatalyst for Aldol Reactions