A Photoreactor-Interfaced Mass Spectrometer: An Online Platform to Monitor Photochemical Reactions.

An experimental platform is reported that allows for the online characterization of photochemical reactions by coupling a continuous flow photoreactor, equipped with LED light irradiation and a dual-tipped ESI source, directly to a mass spectrometer with electrospray ionization. The capabilities of this platform are demonstrated with two classes of photoreactions: (1) the photopolymerization of methyl methacrylate and (2) photocatalyzed alkyne insertion into a 1,2,3-benzotriazinone. The online technique provides rapid information to inform the underlying photochemical mechanism and evaluate the overall photochemistry.

A flow-based transition-metal-catalysed hydrogenolysis strategy to facilitate peptide side-chain deprotection.

Orthogonal deprotection methodologies are an invaluable tool for the construction of site-specially modified peptides. Here, we report a facile 10% Pd/CaCO3-based procedure to selectively mediate Nß-side-chain Cbz-lysis from extended peptide sequences in the presence of trityl and t-Butyl protecting groups.

A Comparison of Immobilised Triphenylphosphine and 1-Hydroxybenzotriazole as Mediators of Catch-and-Release Acylation Under Flow Conditions.

Described herein is a comparative study of immobilised triphenylphosphine (PS-PPh3 ) and 1-hydroxybenzotriazole (PS-HOBt) to mediate amide couplings under continuous flow. Compared to Appel-type amidations (PS-PPh3 ), the developed 'catch-and-release' approach (PS-HOBt) afforded near-quantitative amide conversions. Utilising this strategy, sulfonyl chloride amenability enabled facile access to an expanded library of sulfonate and sulfonamides. Post-constructional peptide modification was also demonstrated, affording two Nß -functionalised pentapeptides in high yields and purities. In contrast to frequently utilised coupling agents, the PS-HOBt resin could be recycled six times without a reduction in efficacy or regeneration requirements.