Reactivity of 5‐(Alkynyl)dibenzothiophenium Salts: Synthesis of Diynes, Vinyl Sulfones, and Phenanthrenes. Issue 29 (5th May 2021)

• Record Type: Journal Article
• Authors: Kafuta, Kevin; Rugen, Christian J.; Heilmann, Tobias; Liu, Tianshu; Golz, Christopher; Alcarazo, Manuel
• Is Part Of: European journal of organic chemistry. Issue 29(2021)
• Page Start: 4038
• Page End: 4048
• Publication Date: 2021-05-05
• Subjects: Addition reactions -- Diynes -- Electrophilic alkynylation -- Sulfonium salts -- Vinyl sulfones; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.202100323
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract: The reactivity of 5‐(alkynyl)dibenzothiophenium salts 1 is explored in the presence of different nucleophiles, dienes, and under photochemical conditions. Reaction with lithium acetylides affords diynes in moderate yields; while depending on the substitution pattern, the reaction with sulfinates delivers either the alkyne transfer products, alkynyl sulfones, or β‐(sulfonium) vinyl sulfones through addition to the C−C triple bond. Similar behavior is observed when tosylamines are used as nucleophiles. Salts of general formula 1 also react with dienes to render the corresponding Diels‐Alder cycloadducts. The vinyl sulfonium salts obtained by these routes further react with nucleophiles through a Michael addition, dibenzothiophene elimination sequence. Alternatively, they also engage in photoinduced radical cyclizations to produce substituted phenanthrenes. Attempts to use this specific addition/radical cyclization sequence for the construction of the 6 a, 7‐dehydroaporphine skeleton present in several families of alkaloids are also described. Abstract : The synthetic potential of 5‐(alkynyl)benzothiophenium salts is further evaluated. In addition to their reactivity as electrophilic alkynylation reagents, they undergo regioselective additions to the C−C triple bond. The products thus obtained can be used for the synthesis of Z ‐vinyl sulfones and 9, 10‐substituted phenanthrenes.