Microfluidics has become recognized as a powerful platform technology associated with a constantly increasing array of applications across the life sciences. This surge of interest over recent years has led to an increased demand for microfluidic chips, resulting in more time being spent in the cleanroom fabricating devices using soft lithography-a slow and expensive process that requires extensive materials, training and significant engineering resources. This bottleneck limits platform complexity as a by-product of lengthy delays between device iterations and impacts on the time spent developing the final application. To address this problem we report a new, rapid and economical approach to microfluidic device fabrication using dry resist films to laminate laser cut sheets of acrylic. We term our method laser lithography and show that our technique can be used to engineer 200 µm wide channels for assembling droplet generators capable of generating monodisperse water droplets in oil and micromixers designed to sustain chemical reactions. Our devices offer high transparency, negligible device-to-device variation, and low X-ray background scattering, demonstrating their suitability for real-time X-ray-based characterization applications. Our approach also requires minimal materials and apparatus, is cleanroom-free and at a cost of around $1.00 per chip, could significantly democratize device fabrication, thereby increasing the interdisciplinary accessibility of microfluidics.

Biaryl phosphines bearing C (Ar) −C (Ar) axial chirality are commonly known and have been successfully applied in many asymmetric catalyses. Nevertheless, the development of a chiral ligand having an axially chiral C (Ar) −N backbone remains elusive due to its undesirable less restricted rotational barrier. In fact, it is highly attractive to overcome this challenge in ligand development as the incorporation of an N-donor component at the chiral axis is more favorable toward the transient metal coordination, and thus, a better outcome of stereocommunication is anticipated to the approaching substrates. Herein, we present a rational design of a new collection of chiral phosphines featuring a C−N axial chirality and their applications in enantioselective Suzuki−Miyaura cross-coupling for accessing highly steric hindered tetra-ortho-substituted biaryls (26 examples up to 98:2 er). It is worth noting that the embodied carbazolyl framework is crucial to succeed the reaction, by the fruitful steric relief of bulky substrate coordination and transmetalation via a fleeting Pd−N jumping to Pd-π fashion. DFT calculation reveals an interesting Pd-arene-walking characteristic across the carbazolyl plane for attaining a lower energy-preferred route in a catalytic cycle. The theoretical study successfully predicts the stereooutcome and matches the enantioselectivity with the experimental results.

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Sonogashira cross-coupling protocol, typically showing the reaction between aryl/vinyl halide and terminal alkyne, has been a widely used protocol for constructing C(sp 2 )-C(sp) bond. The resulting internal alkynes are highly versatile for reaching differently functionalized alkyne-containing scaffolds or serving as valuable synthetic synthons to many other functional groups. It is worth noting that products originated from this coupling reaction are mostly applicable to be transformed into corresponding Z-alkene, alkane, or heterocyclic moieties in natural product syntheses. The reaction conditions and catalyst systems are able to be tweaked in order to facilitate the activation of steric hindered and/or electron-rich electrophiles. Pd-catalyzed copper-free Sonogashira coupling reaction has caught increasing attention as the improved method can be more environmentally friendly. What is more, the conditions of the coupling reaction can be readily amended to allow the fusion of other carbonylation or decarboxylation step in the catalytic cycle, and thus allow more complex yet versatile convergent synthesis to proceed in an operationally simple one-pot manner.