Visible‐Light‐Mediated C(sp
<sup>3</sup>
)–H Thiocarbonylation for Thiolactam Preparation with Potassium Sulfide
作者:Wei Tan、Cuihong Wang、Xuefeng Jiang
DOI:10.1002/cjoc.201900360
日期:2019.12
thiolactam preparation with potassium sulfide via visible‐light‐mediated C(sp3)–H thiocarbonylation, in which polysulfide dianions and radical anions generated from potassium sulfide were the key active species. A variety of thiolactams were straightforward established under mild conditions. Moreover, it was successfully applied to structural modification of tetrahydroberberine.
(QM) computations and well-designed experiments on the reaction mechanism revealed that this thiocarbonylation depends on the specific solvent that initially drives this reaction through the intermolecular hydrogen atom transfer (HAT). And the following single electrontransfer (SET) induces the electron-catalyzed C–S bond formation and intramolecular HAT realizing the final establishment of the CS bond
Treatment of 3-hydroxyisoindolin-1-ones 1 with Lawesson reagent gave isoindoline-1-thiones 2, by direct thionation and reductive elimination of hydroxy group, in good yields.
Photoreactions of isoindoline-1-thiones with alkenes: unusual formation of tricyclic isoindolines
作者:Takehiko Nishio、Norikazu Okuda
DOI:10.1021/jo00040a049
日期:1992.7
Photochemical cycloaddition reactions of cyclic thioamides and alkenes have been examined. Irradiation of 2-arylisoindoline-1-thiones 1 in the presence of alkenes 2 gave the unexpected tricyclic isoindolines 3-18. The formation of tricyclic isoindolines can best be explained in terms of the intermediacy of aminospirothietane 27, formed by [2 + 2] photocycloaddition of the C=S double bond of 1 to the C=C double bond of 2. Ring cleavage of the resultant amino thietane, assisted by the participation of the nitrogen lone-pair electrons, produced zwitterions 28 and 29 or 1-mercaptoethylisoindole (30). Subsequent nucleophilic attack of the thiol anion on the iminium carbon of 29 or attack of the thiol group on C-3 of 30 gave the final products. Irradiation of isobenzofuran-1-thione (22) and isobenzothiophene-l-thione (23) in the presence of tetramethylethylene (2a) gave the corresponding spirothietanes 24 and 25.
1-Ethylthio-2R-isoindoles. An example of nonsynchronous addition in the diels-alder reaction
作者:V. A. Kovtunenko、T. T. Dobrenko、Z. V. Voitenko、A. K. Tyltin、F. S. Babichev