Synthesis of Sulfonyl Azides via Diazotransfer using an Imidazole-1-sulfonyl Azide Salt: Scope and ¹⁵N NMR Labeling Experiments

Imidazole-1-sulfonyl azide hydrogen sulfate is presented as an efficient reagent for the synthesis of sulfonyl azides from primary sulfonamides. The described method is experimentally simple and high-yielding and does not require the addition of Cu salts. Furthermore, ¹⁵N NMR mechanistic studies show the reaction proceeds via a diazo transfer mechanism. Imidazole-1-sulfonyl azide hydrogen sulfate provides a considerable advantage over existing diazo transfer reagents in terms of impact stability, cost, and ease of use

Microwave-Assisted Branching Cascades: A Route to Diverse 3,4-Dihydroquinazolinone-Embedded Polyheterocyclic Scaffolds

A novel metal-free microwave-assisted branching cascades strategy for the efficient synthesis of 3,4-dihydro­quinazolinone-embedded polyheterocyclic scaffolds is reported. Starting from in situ generated key <i>N</i>-acyliminium ion precursors, 12 distinct and skeletally diverse polycyclic frameworks were accessed in a single step/pot via adjustment of the nucleophile(s) and reaction conditions. Postcascade functionalization of these compounds was also demonstrated, proving the utility of this method in accessing structurally diverse chemical entities

Acyl Amidines by Pd-Catalyzed Aminocarbonylation: One-Pot Cyclizations and ¹¹C Labeling

A protocol for the carbonylative synthesis of acyl amidines from aryl halides, amidines, and carbon monoxide catalyzed by Pd(0) is reported herein. Notably, carbon monoxide is generated ex situ from a solid CO source, and several productive palladium ligands were identified with complementary benefits and substrate scope. Furthermore, sequential one-pot, two-step protocols for the synthesis of 1,2,4-triazoles and 1,2,4-oxadiazoles via acyl amidine intermediates are reported. In addition, this approach was extended to isotopic labeling using [11C]carbon monoxide to allow, for the first time, synthesis of 11C-labeled acyl amidines as well as a 11C-labeled 1,2,4-oxadiazole