959682-63-4Relevant academic research and scientific papers
Dihydropyran as a template for lactone synthesis
Brichacek, Matthew P.,Carlson, Robert M.
, p. 3541 - 3549 (2007)
3,4-Dihydro-2H-pyran (DHP) was efficiently transformed into 4-thiophenyl-3,4-dihydro-2H-pyran. This intermediate was converted to the corresponding 1,3-O,S-allylic carbanion with t-butyllithium and selectively alkylated at the carbon α to the sulfur with
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.
