33141-61-6Relevant articles and documents
Direct Allylic C(sp3)-H Thiolation with Disulfides via Visible Light Photoredox Catalysis
Hong, Soon Hyeok,Kang, Byungjoon,Kim, Jungwon
, p. 6013 - 6022 (2020/07/03)
In spite of the wide utility of allyl thioethers, the direct catalytic allylic C(sp3)-H thiolation remains elusive. Herein, we report the direct allylic C(sp3)-H thiolation mediated by visible light photoredox catalysis. The use of in situ-generated thiyl radical from disulfide as a hydrogen atom transfer (HAT) reagent and a coupling partner enabled selective cleavage of the allylic C(sp3)-H bond followed by C(sp3)-S bond formation. The undesired hydrothiolation, a prevalent reaction from facile thiyl radical addition to olefins, was prevented by the immediate deprotonation of thiol under basic conditions. A wide range of diaryl disulfides and olefins participated in the reaction, producing allyl thioethers with high efficiency. Mechanistic investigations revealed the participation of the photocatalyst as a redox mediator, which was crucial for the transformation of the allyl radical into the allyl cation and further ionic coupling process. Based on the proposed mechanism, a limitation in the synthesis of alkyl allyl sulfide was solved with a rationally designed more reducible unsymmetrical disulfide, which makes the desired catalytic cycle operative.
Highly selective sulfoxidation of allylic and vinylic sulfides by hydrogen peroxide using a flavin as catalyst
Linden, Auri A.,Krueger, Lars,Baeckvall, Jan-E.
, p. 5890 - 5896 (2007/10/03)
A highly chemoselective oxidation of allylic and vinylic sulfides to the corresponding sulfoxides has been developed using flavin 1 as the oxidation catalyst and hydrogen peroxide as the terminal oxidant. The sulfoxides were formed in good to excellent yields in a highly selective manner even when an excess of the oxidant was used. Sulfone formation was completely suppressed to 0.5% (in one single case 1.5% sulfone was detected). No epoxidation of double bonds or interference with other functional groups was observed under the reaction conditions. The general applicability was demonstrated by the selective oxidation of various allylic and vinylic sulfides having different electronic properties. A number of functionalities including hydroxy, acetoxy, amino, silyloxy, and formyl groups are tolerated under these mild reaction conditions.
Syntheses of Biologically Important Carbohydrates, 32. - Studies on the Preparation and Oxyamination of a Methyl-branched Pent-3-enopyranoside
Dyong, Ingolf,Tacken, Angelika
, p. 564 - 575 (2007/10/02)
The glycero-pent-3-enopyranoside 4c prepared in several steps from L-arabinose was transformed into the phenylsulfenic acid ester 4d which undergoes -sigmatropic rearrangement to give the 4-phenylsulfinyl derivative 5a.While the carbocyclic analogue 7c was easily methylated to give 8, subsequently rearranged, and subjected to phosphitolysis to yield the allyl alcohol derivative 6b, on similar treatment no reaction of 5a could be observed. - An alternative method started with the 2,3-epoxy-4-ulose 14 which was transformed into the ketone 11b, and this was methylated to give the epimers 9b and 10b.Both on treatment with thionyl chloride led to the glycal 13 as well as the desired 4-C-methyl-branched pent-3-enopyranoside 12.The glycero-pent-3-enopyranoside 4a could be transformed into the crystalline amino sugar components 18 and 19.
