Catalysis with chalcogen bonds: neutral benzodiselenazole scaffolds with high-precision selenium donors of variable strength

Abstract

Benzodiselenazoles are introduced for efficient anion binding and unprecedented non-covalent catalysis in the focal point of neutral selenium-based chalcogen-bond donors.

Mechanosensitive Oligodithienothiophenes: Transmembrane Anion Transport Along Chalcogen‐Bonding Cascades

“…This motif thus offers for chalcogen bonds what bipyridine lone pairs offer for cation binding and bipyrroles for anion binding with hydrogen bonds. Anion transport and catalytic activities increased with increasing depth of the σ holes in electron‐deficient DTTs such as 5 compared to 6 .…”

Chalcogen‐Bonding Catalysis: From Neutral to Cationic Benzodiselenazole Scaffolds

“…[ ][ ] In the most active chalcogen‐bonding BDS catalyst reported so far, i.e . 1 , the BDS scaffold is decorated with electron‐withdrawing cyano and sulfone acceptors to deepen the σ holes on the endocyclic Se donors ( Figure ,g ) . The superiority of selenium compared to the less polarizable sulfur donors for chalcogen‐bonding catalysis has been clearly demonstrated .…”

“…The use of intermolecular chalcogen bonds in functional systems in solution is rare and recent, non‐covalent chalcogen‐bonding catalysis has been introduced only last year. [ ][ ][ ] The key to success was the idea that the somewhat awkwardly ‘hidden’ position of the σ holes on the side of chalcogen‐bond donors turns into an advantage as soon as transition‐state recognition in the focal point of two adjacent donors is considered . Dithiophenes ( Figure ,d ) were taken as starting point to think about chalcogen‐bonding scaffolds for the recognition of electron‐rich motifs in ground and transition state that would reflect the fundamental general versatility of classics such as metal‐binding bipyridines ( Figure ,b ) or hydrogen‐bonding bipyrroles ( Figure ,c ).…”

“…However, the formal substitution of the sulfur donors in DTTs with stronger selenium donors again turned the bite angle out of focus, this time becoming too large ( Φ 3 = 53°) because of the long C–Se bonds. This mismatch was corrected to Φ 3 = 45° by replacing the single‐atom bridge in DTTs with a double‐atom bridge in benzo[1,2‐ d :4,3‐ d’ ]di([1,3]selenazole)s (BDS, Figure ,f ) …”

“…In this reaction, chalcogen‐bonding catalysts are used in stoichiometric amounts because of their possible inactivation by the eliminated bromide anion and thus act formally as activators rather than as catalysts. However, the previously confirmed function of 1 and 5 to catalyze transfer hydrogenation of quinolines and imines justifies the use of the term catalyst …”