Formation of glycosyl trichloroacetamides from trichloroacetimidate donors occurs through an intermolecular aglycon transfer reaction

To probe the reaction mechanism, underlying the rearrangementofoft-used trichloroacetimidate glycosyl donors into the correspondinganomeric trichloroacetamides, we have used a combination of C-13- and N-15-labeled glycosyl trichloroacetimidate donorsin a series of crossover experiments. These unambiguously show thattrichloroacetamides are formed via an intermolecular aglycon transfermechanism. This insight enables the design of more effective glycosylationprotocols, preventing the formation of dead-end side products.Bio-organic Synthesi

Palladium-Catalyzed Cascade to Benzoxepins by Using Vinyl-Substituted Donor-Acceptor Cyclopropanes

A palladium‐catalyzed intermolecular cascade (4+3) cyclocondensation of salicylaldehydes and vinylcyclopropanes is reported. A key feature of the reaction is the use of a phosphonate group as an acceptor moiety on the cyclopropane, exploiting its propensity to undergo olefination with aldehydes. Subsequent O‐allylation enabled the formation of a range of substituted benzoxepinsWith a novel chiral ligand, the products were obtained in generally good yield and with reasonable enantioselectivity

Facile Synthesis of Tuneable Azophosphonium Salts

Azophosphonium salts have a facile synthesis and can be readily tuned at the para position of the aryl group and at the phosphorus position with the use of bulky phosphines, leading to a range of coloured compounds. A relation between the Hammett σ+para constant and the colour and 31P NMR chemical shift was explored. The compounds were characterised by NMR spectroscopy, UV/Vis spectroscopy and single‐crystal X‐ray structure crystallography