アルキンへの光化学的チオエステル転移：選択的ヒドロチオカルボニル化による
Amit Pal1, Prakash Maity1, Fathima Niloofar1
1School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram, Maruthamala PO, Vithura, Thiruvananthapuram, Kerala 695551, India.
Abstract:
We report the first hydrothiocarbonylation of (un)activated alkynes using bench-stable 1,4-DHP thioester surrogates under photochemical conditions, enabling a general route to (E)-α,β-unsaturated thioesters with excellent regio- and stereoselectivity. A Pd/photoredox catalytic system facilitates DHP thioester activation and site-selective hydrocarbonylation while controlling photoisomerization and side reactions. Moreover, a combination of benzil and boron Lewis acid pairs promotes E-to-Z photoisomerization, accessing (Z)-α,β-unsaturated thioester.
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関連する概念動画
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
02:35Electrophilic Addition to Alkynes: Hydrohalogenation
02:38Electrophilic Addition to Alkynes: Halogenation
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
02:40Alkynes to Aldehydes and Ketones: Acid-Catalyzed Hydration
Analogous to alkenes, alkynes also undergo acid-catalyzed hydration. While the addition of water to an alkene gives an alcohol, hydration of alkynes produces different products such as aldehydes and ketones.
02:33Preparation and Reactions of Thiols