An efficient and experimentally straightforward method for the stereoselective synthesis of a variety of β-nitroα-amino carboxylic acids via aza-Henry (nitro-Mannich) reaction of aldimines is disclosed, yielding either anti-or a rarely reported syn-configuration. The reaction operates directly on free glyoxylic acid and generates imine species in situ. Crystallization-controlled diastereoselectivity enables isolation of the target compounds in high enantio-and diastereomeric purities by a simple filtration.

Interestingly, β-nitrostyrenes, typically bench stable compounds, are highly promising cross-coupling partners, due to their excellent availability and well understood reactivity. In this review, we report on the discovery and advancements, in the field of stereoselective, denitrative cross-couplings of β-nitrostyrenes with miscellaneous organic reagents. The rapidly expanding field offers alternative access to a broad range of functionalized alkenes, including β-alkylated styrenes, chalcones, stilbenes, cinnamic acids, and conjugated sulfones and phosphonates. The most important mechanistic pathways are briefly discussed, to familiarize readers with the elementary reactions occurring during the coupling.

A stereoselective, denitrative cross-coupling of β-nitrostyrenes with N-alkylpyridinium salts for the preparation of functionalized styrenes has been developed. The visible-light-induced reaction proceeds without any catalyst at ambient temperature. Broad in scope and tolerant to multiple functional groups, the moderately yielding transformation is orthogonal to several traditional metal-catalyzed cross-couplings.

Protodenitration, a direct reduction of nitroalkanes to corresponding alkanes, already spans two centuries and is enabled by various reagents. This mini-review provides a historical development of the fundamental transformation and highlights the governing position of the Ono-Tanner reaction employing tributyltin hydride. Due to the unchallenged dominance of the toxic tributyltin hydride and environmentally unpopular solvents sharply contrasting with modern ecological trends, the current situation was dubbed "the last fortress of tin's tyranny."[a

The Front Cover visually represents our review “The Last Fortress of Tin′s Tyranny – Protodenitration of Nitroalkanes“. ”Once upon a time, in a small corner of a faraway land full of nitroalkanes, a small town called “Protodenitrations” started coming to life. Unfortunately, a sneaky tin, hungry for power, soon took the opportunity and overtook the small, still fragile community, establishing himself as the king. The kingdom ruled by Tin The Tyrant has expanded since then, spreading its roots all over the continent. Despite a few attempts to dethrone the Tyrant, he remains undefeated. However, rumors are starting to spread that an army of reagents is beginning to gather. Could the end of the last fortress of the tyranny of tin be in sight?“ This review provides the historical development and highlights the governing position of the Ono–Tanner reaction employing tributyltin hydride. Due to the unchallenged dominance of the toxic tributyltin hydride, the current situation was dubbed “the last fortress of tin′s tyranny.” The authors would like to thank Katarína R. Detková for the graphic project and creation. More information can be found in the Review by P. Jakubec et al.