A Transition‐Metal‐Free and Base‐Mediated Carbene Insertion into Sulfur‐Sulfur and Selenium‐Selenium Bonds: An Easy Access to Thio‐ and Selenoacetals

Abstract

A transition-metal-free and base-mediated carbene insertion across sulfur-sulfur and selenium-selenium bonds has been developed by employing N-tosylhydrazone as a stable and safe carbene precursor. The ylide formation from carbene followed by Stevens rearrangement are considered to be the key steps. This thiol and selenolfree protocol delivers thioacetals and selenoacetals in good to excellent yields in short reaction time with good functional group tolerance. A one-pot synthesis involving in situ generation of tosylhydrazone has also been demonstrated.

Advances in [1,2]-Sigmatropic Rearrangements of Onium Ylides via Carbene Transfer Reactions

“…Finally, the desired product 301 is formed after a [1,2]-sigmatropic rearrangement (Scheme 29, c). 64 In 2016, the Xu group studied the metal-free S-S bond insertion reaction of donor/acceptor diazoacetates 53 under thermal conditions and by theoretical calculations. The latter revealed the initial thermal formation of a singlet carbene intermediate 310 that can either undergo intersystem crossing to a triplet carbene or ylide formation with disulfide 304.…”

Luxury of N‐Tosylhydrazones in Transition‐Metal‐Free Transformations

“…In 2017, our research group developed a carbene insertion strategy into S−S and Se−Se bonds using N ‐tosylhydrazone as a safe carbene precursor (Scheme ) . The reaction of aryl aldehyde‐derived N ‐tosylhydrazones and diaryl disulfides in the presence of KO‐ t‐ Bu afforded a series of thioacetals 179 within a short reaction time.…”

Star-shaped triarylamines – One-step metal-free synthesis and optoelectronic properties

“…In light of this sustainability, there is also a growing consensus on rethinking the traditional organic synthesis in order to establish new heavy-metal-free synthetic methods. [13][14][15] This is not only important from an environmental point of view but also can enhance the performance and reproducibility of the respective optoelectronic devices, since even lowest metal traces and concurrent metal-organic interactions can influence the electronic properties. 16,17 So far, TAAs have been synthesized by reacting two pre-functionalized coupling partners in the presence of transition metal catalysts (e.g.…”