Sulfur ylides, first reported by Ingold and Jessop in 1930, have long occupied a central position in organic synthesis owing to their ambiphilic character and diverse reactivity. In recent years, ylide chemistry has progressed beyond classical systems toward the development of mixed ylides, in which two distinct heteroatoms are incorporated within a single ylide framework. Among these, sulfur based mixed ylides have emerged as powerful and versatile intermediates. Their unique electronic structure enables polarity inversion at the α-carbon, allowing this position to exhibit both nucleophilic and electrophilic behavior and thereby granting access to a broad range of reactive intermediates, including carbenes, radicals, carbocations, and carbynes. The discovery of the first sulfur based mixed ylide in 2018 marked a significant milestone, opening new avenues for reactivity and selectivity. This Review summarizes recent advances in sulfur based mixed ylide chemistry, with particular emphasis on their mechanistic features, and applications in diverse organic transformations.
An electrochemical approach for regioselective 7-endo-dig selenocyclization of N-benzyl propiolamides with diselenides has been developed. This methodology circumvents the need for metal reagents or oxidants, thereby exhibiting excellent functional group tolerance and substrate compatibility. A diverse array of selenated benzo[c]azepinones can be obtained with good to excellent regioselectivity and yields. Furthermore, gram-scale synthesis and subsequent transformations of the products can be readily achieved under straightforward experimental protocols.
The nitrate electroreduction reaction (NO3-RR) provides a low-carbon and environmentally friendly strategy for ammonia production. Here, a sustainable method for synthesizing carbon nanosheets is developed by assembling biomass molecules on a boric acid template, followed by thermal annealing. During this process, the introduction of Fe3+ and Cu2+ ions enables the formation of Fe-doped CuO nanoparticles embedded in carbon nanosheets (Fe-CuO/C). The Fe-CuO/C shows high activity for the NO3-RR resulting in a low potential of 0.089 and -0.192 V vs. RHE at -10 and -50 mA cm-2, with high ammonia yield and faraday efficiency. Theoretical calculations indicate that the *NO to *NOH step is the rate-determining step during the NO3-RR. The doping of Fe effectively reduces the energy barrier of this step.
Alkali metal ketenyls, [M(RCCO)], were found to exhibit diverging reactivities towards ammonia depending on the substitution pattern. Ketenyl anions with strong electron-withdrawing groups (R = CN or tosyl) react with NH3 to form β-ketoamides, while the phosphinoyl substituted systems (R = Ph2P(E), E = S, Se) activate all three N-H bonds, resulting in a trianionic triamide. This triamide exhibits a dimeric structure with the six potassium cations forming a unique planar triangular {K6}6+ cluster.
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