Exploring the Photophysical and Photochemical Properties of N-(Thioalkyl)-saccharins as an Alternative Route to the Synthesis of Tricyclic Sultams

Abstract

Photocyclization of N-(thioalkyl)-saccharin was carried out to obtain different polycyclic sultams in good yields. These photoreactions were efficient under inert atmosphere and acetone triplet-sensitized conditions indicating that the triplet excited state is directly involved in the formation of annulated products. The presence of molecular oxygen changes product distribution, and only photo-oxygenation products (sulfoxides and sulfones) were found. This result is especially valuable since, by simple changing from nitrogen- to oxygen-saturated solvent conditions, the reaction outcome can be tuned from cyclized to sulfur oxidation products. Additionally, steady-state photolysis, electrochemistry, and laser time-resolved spectroscopic studies confirmed that these reactions mainly proceeded by intramolecular electron transfer (ET) between the triplet excited saccharin moiety and sulfur atom.

Regioselective Photocycloaddition of Saccharin Anion to π-Systems: Continuous-Flow Synthesis of Benzosultams

“…Also, the singlet energy of E s = 333 kJ mol −1 was extracted from the spectroscopic characterization; this value is lower compared to that of other N-alkyl saccharins measured. 7 Scheme 3. Possible Pathways for the Benzosultam Products Formation Computational Study.…”

“…6 More recently, the photocyclization reactions of N-(thioalkyl)saccharins were carried out in our group to obtain different polycyclic sultams in good yields. 7 These results motivated us to continue exploring the photoreactivity of saccharin oriented to synthetic applications. In this work, we focused on the synthesis of benzo-fused seven-membered sultams by photocycloaddition reaction.…”

Sultams: Recent Syntheses and Applications

“…Mansilla, Argüello, et al explored the photophysical and photochemical properties of N ‐(thioalkyl)saccharins 91.1 and prepared various tricyclic sultams 91.2 and 91.3 through photocatalyzed reactions (Scheme ) …”

“…[77] Mansilla, Argüello, et al explored the photophysical and photochemical properties of N-(thioalkyl)saccharins 91.1 and prepared various tricyclic sultams 91.2 and 91.3 through photocatalyzed reactions (Scheme 91). [78] Recently, Wang, He, et al synthesized the two different sets of polycyclic sultams 92.3 and 92.4 by treatment of Nsulfonyl ketimines 92.1 with arynes 92.2 through selective aza-Diels-Alder and domino [4+2]/[2+2] cycloaddition reactions (Scheme 92). [79] Mohar and co-workers synthesized stereopure functionalized benzosultams 93.2 and 93.3 from six-membered sultams 93.1 through consecutive ruthenium(II)-catalyzed dynamic kinetic resolution and asymmetric transfer hydrogenation (Scheme 93).…”

Methanol-Assisted Phthalimide Ring Opening: Concerted or Stepwise Mechanism?

“…Phthalimide and its derivatives are the precursors of anthranilic acids, which are widely used to synthesize useful organic compounds like azo dyes and saccharins. − They have also been used to synthesize pharmaceutical molecules containing benzamides. − Recently, Piou and Rovis have developed an elegant reaction methodology with N -enoxyphthalimides for the syn -carboamination of alkenes, in which N -enoxyphthalimides serve as the source of both C and N functionality and the Rh­(III) complexes serve as the catalysts . Reportedly, the use of methanol as the solvent is critical to improve the efficiency of this carboamination reaction …”