Recent advances in the annulative cyclization of 2-alkynylanilines: transition metal, metal-free, photoredox, and electrochemical approaches.

2-Alkynylanilines have been recognized as versatile precursors for the efficient construction of complex heterocyclic scaffolds, which has generated tremendous interest in medicinal and materials chemistry. Their complex reactivity has propelled advances in green synthetic strategies, extending beyond traditional transition metal-mediated and metal-free processes to innovative photo- and electrocatalytic methodologies. Each of these methodologies has its own merits: transition metal catalysis provides high reactivity and selectivity, metal-free processes are in line with the principles of green chemistry, and photo- and electrocatalytic processes offer environmentally friendly, mild, and cost-effective alternatives.

Engaging hydrazine hydrate as a hydrogen source for cobalt(II)-catalysed transfer hydrogenation of nitroaromatics.

Herein, we report earth-abundant cobalt(II)-catalysed hydrogenation of nitroaromatics to amines by utilizing hydrazine hydrate as the liquid hydrogen carrier. The significant highlight of this method is the production of greener byproducts. Remarkably, the developed method is promising in accessing drugs like butamben and benzocaine and other potential pharmaceutical precursors.