Synthesis of cis-thiiranes as diastereoselective access to epoxide congeners via 4π-electrocyclization of thiocarbonyl ylides

Abstract

Organochalcogen heterocycles are ubiquitously present and widely utilized in various fields. Among them, oxirane has been extensively studied, and all of the stereoisomeric forms are readily available. In contrast, synthetic studies on thiirane were rarely reported, and thus the useful sulfur-congener of oxirane has been difficult to access in a stereodefined form. In this research, a general stereoselective synthesis of cis-thiiranes is accomplished by taking advantage of stereospecific electrocyclization of trans-thiocarbonyl ylides, which are generated in situ from readily available E,E-aldazine N-oxides upon treatment with Lawesson’s reagent. This newly developed practical method provides a variety of cis−1,2-diarylthiiranes as essentially single diastereomers in high yields under mild reaction conditions. The intermediacy of trans-thiocarbonyl yilde is confirmed by mechanistic experiments, and the excellent stereocontrol is rationalized by DFT calculation.

Thiourea-Mediated Stereospecific Deoxygenation of Cyanoepoxides to Access Highly Diastereopure Alkenyl Nitriles

“…Notably, the only existing method for synthesizing cis -3,4-disubstituted pyrolidines relies on cyclization strategy, accompanied by the generation of trans -isomers . In contrast, our work provides a more efficient cycloaddition strategy. , …”

A guide to modern methods for poly(thio)ether synthesis using Earth-abundant metals

“…42,43,48 Thiiranes can also be produced through thiocarbonyl ylide or aldazine N-oxide intermediates, which can preserve stereo-structure, but these are generally more difficult. 49 Fig. 3 shows an overview of these methods, with several other methods reported in the following ref.…”

Domino Sonogashira coupling/metal carbene-involved annulation enabled by Pd/Cu relay catalysis: rapid assembly of indazole-containing biheteroaryls

“…11 Thiocarbamate attack on Cu-carbene forms an S-containing three-membered ring intermediate G , which lost one sulfur atom to produce biheteroaryl product 3a . 14,15…”