Recent synthesis of thietanes

Abstract

Thietanes are important aliphatic four-membered thiaheterocycles that are found in the pharmaceutical core and structural motifs of some biological compounds. They are also useful intermediates in organic synthesis. Various synthetic methods of thietanes have been developed, including inter- and intramolecular nucleophilic thioetherifications, photochemical [2 + 2] cycloadditions, ring expansions and contractions, nucleophilic cyclizations, and some miscellaneous methods. The recently developed methods provide some new strategies for the efficient preparation of thietanes and their derivatives. This review focuses on the synthetic methods to construct thietane backbones developed during 1966 to 2019.

Mechanisms and Synthetic Strategies in Visible Light‐Driven [2+2]‐Heterocycloadditions

“…the thia-PB variant). [7] Thietanes are versatile building blocks in organic synthesis for the preparation of other sulfur-containing acyclic and heterocyclic compounds, [8] while representing another important class of pharmaceutical cores. [9] A fundamental requirement in all the photochemical reactions is the presence of a chromophoric unit capable of absorbing light at the irradiation wavelength.…”

“…On the other hand, the synthesis of functionalized thietanes 3 c have been also described through [2+2]‐photocyloadditions using thiocarbonyl compounds (i.e. the thia‐PB variant) [7] . Thietanes are versatile building blocks in organic synthesis for the preparation of other sulfur‐containing acyclic and heterocyclic compounds, [8] while representing another important class of pharmaceutical cores [9]…”

Lewis Acid‐Mediated Ring Contraction of 2,4‐Diaryl‐2,3‐dihydro‐1H‐1,5‐benzodiazepines: Access to 2‐Aryl‐1‐styrylbenzimidazoles

“…Recently, it was documented that the base‐mediated ring contraction of 1,2‐diaryl‐2,3‐dihydro‐1 H‐ 1,5‐benzodiazepines produced both 2‐arylbenzimidazoles and 2‐arylquinoxalines accompanied by styrenes ( Scheme 1 ,c ) [15] . Ring contraction is a useful strategy for transformations of readily available heterocycles into relatively small heterocycles [16–19] . 1,2‐Diaryl‐2,3‐dihydro‐1 H‐ 1,5‐benzodiazepines were readily prepared from o ‐phenylenediamine with chalcones [10] and 1‐phenylbut‐2‐en‐1‐one [20] in the presence of piperidine followed by treatment with acetic acid.…”

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

“…Among them, three-membered heterocycles containing a chalcogen are ubiquitous subunits, and significant efforts have been dedicated to the development of synthetic methods for oxiranes 12,13 . The sulfur congeners, thiiranes are also useful synthetic precursors that can be transformed into an array of functional groups via ring-opening or desulfurization [14][15][16][17][18][19][20] . In addition, versatile sulfur-containing polymers can be produced via ring-expansion polymerizations or copolymerizations [21][22][23][24][25] .…”