Details

Autor(en) / Beteiligte

• Strieth-Kalthoff, Felix
• Henkel, Christian
• Teders, Michael
• Kahnt, Axel
• Knolle, Wolfgang
• Gómez-Suárez, Adrián
• Dirian, Konstantin
• Alex, Wiebke
• Bergander, Klaus
• Daniliuc, Constantin G.
• Abel, Bernd
• Guldi, Dirk M.
• Glorius, Frank

Titel

Discovery of Unforeseen Energy-Transfer-Based Transformations Using a Combined Screening Approach

Ist Teil von

• Chem, 2019-08, Vol.5 (8), p.2183-2194

Ort / Verlag

Elsevier Inc

Erscheinungsjahr

2019

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The discovery of novel (catalytic) transformations and mechanisms is commonly based on rational design. However, many discoveries have resulted directly from experimental serendipity. Building on this, we report a two-dimensional screening protocol, combining “mechanism-based” and “reaction-based” screening and its application to the field of visible light photocatalysis. To this end, two energy-transfer-based cycloaddition reactions could be realized: a notably endergonic energy transfer process allows for the dearomative cycloaddition of benzothiophenes and related heterocycles. Moreover, by sensitization of enone moieties, a [2+2]-cycloaddition to alkynes and an unexpected cycloaddition-rearrangement cascade were discovered. Advanced spectroscopic techniques (in particular transient absorption spectroscopy and pulse radiolysis) were utilized to investigate the underlying photophysical processes and gain insight into reaction kinetics. Combining these results with further mechanistic analysis can eventually turn out to be helpful upon knowledge-driven development of improved systems. Such screening approaches can thus provide complementary access toward novel and more efficient catalytic protocols. [Display omitted] •Development of a two-dimensional screening strategy for reaction discovery•Visible-light-mediated dearomative cycloaddition of heterocycles•Mechanistic analysis by transient absorption spectroscopy and pulse radiolysis Driven by the continuous demand for more efficient and sustainable synthetic reactions, the discovery of novel (catalytic) reactivity patterns remains a major challenge of synthetic chemistry. The discovery of such processes is commonly based on rational design, i.e., the expansion of previously acquired knowledge to new substrate classes or reaction types. However, considering that many groundbreaking discoveries have resulted from experimental serendipity, serendipity-based screening methodologies have been developed as a complementary tool for the discovery of novel transformations. Particularly in the context of visible-light-mediated photocatalysis, which provides a powerful platform from which to develop new radical-based transformations, screening methodologies still have significant potential to discover new reactivity modes. How can catalytic reactions be discovered? Here, a two-dimensional screening strategy for reaction discovery is described. For this purpose, the investigation of single mechanistic steps is merged with combinatorial screening. As a showcase, application to the field of visible light photocatalysis allowed for the discovery of three unexpected cyclization reactions. Extensive mechanistic analysis by advanced spectroscopic and computational tools enabled insights into the underlying molecular processes. In particular, a significantly endergonic sensitization event could be discovered and substantiated by transient absorption spectroscopy.