Recent developments of ketene dithioacetal chemistry

“…They also allow the formation of valuable building blocks that can be used for diverse transformations in organic chemistry (e.g., Umpolung) [3]. Ketene 1,3-dithioacetals [4] are of particular interest as attractive nucleophiles for the addition to halonium ions [5–6], acyl chlorides [7] and other electrophiles [8–10] and are broadly used as precursors for [2 + 2]-cycloaddition [11–12], (aza)-Diels–Alder reaction [13–14], and [3 + 2]-cycloaddition reactions [15–16]. The products of these reactions are diversely substituted (ketene) dithiolanes or dithianes which allow a wide range of transformations like oxidation [17], fluorination [18] and cyclative reaction with [19–20] and without conservation [21–22] of the dithioacetal functionality.…”

Section: Introductionmentioning

confidence: 99%

Addition of dithi(ol)anylium tetrafluoroborates to α,β-unsaturated ketones

Huang

Nguyẽ̂n

Gräßle

et al. 2018

Beilstein J. Org. Chem.

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In the presented study, dithi(ol)anylium tetrafluoroborates are added to α,β-unsaturated ketones in a Michael-type reaction yielding diverse substituted ketene diothi(ol)anes. The reactions proceed at room temperature in 1 or 13 h without the need of further additives. The presented procedure is in particular useful for dithi(ol)anylium tetrafluoroborates without electron-withdrawing groups in α-position. This is advantageous with respect to previous approaches, which were limited to the use of ketene dithioacetals substituted with electron-withdrawing groups. Aiming for the systematic investigation of possible steric and electronic influences on the outcome of the reaction, various combinations of electrophiles and nucleophiles were used and the results of the reactions were compared based on the type of the used dithioacetal. The scope of the presented procedure is shown with four additional transformations including the use of additional electrophiles and nucleophiles, the use of a chiral auxiliary and subsequent reduction of selected products. Additionally, we extended the reaction to the synthesis of diene dithiolanes by addition of an ynone to α-alkyl or aryl-substitued dithiolanylium TFBs.

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“…Ketene dithioacetals are versatile synthons to generate various key intermediates for further exploration towards several new chemical scaffolds. 8 Functionalized ketene dithioacetals (1a-h, Scheme 1) were synthesized from the reaction of appropriate aromatic ketones with CS 2 followed by methyl iodide. Our final compounds (11a-18a, Table 1) contain an amide bond at C-3 position on α-pyranone ring.…”

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confidence: 99%