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Acidic Condensation of BODIPYs with Aldehydes: A Quick and Versatile Route to Alkenyl‐BODIPYs and C(sp 3 )‐Connected DYEmers
Author(s) -
Ahrens Johannes,
Cordes Birte,
Wicht Richard,
Wolfram Benedikt,
Bröring Martin
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201601568
Subject(s) - chemistry , bodipy , knoevenagel condensation , condensation , formaldehyde , phenylacetaldehyde , yield (engineering) , photochemistry , condensation reaction , aldehyde , base (topology) , organic chemistry , protonation , combinatorial chemistry , fluorescence , catalysis , ion , physics , materials science , quantum mechanics , metallurgy , thermodynamics , mathematical analysis , mathematics
The condensation of aldehydes with BODIPY (boron dipyrrin) luminophores was investigated. Formaldehyde can be used to connect two BODIPYs at each of the three pyrrolic C positions (α‐, β‐, and β′‐positions) in a quick and highly selective manner, yielding new DYEmers (di‐ and oligomeric BODIPY derivatives) with varied photophysical properties. Benzaldehydes form DYEmers only at the β‐ and the β′‐positions. For aliphatic aldehydes the DYEmer formation competes with the elimination of water from a proposed alcohol intermediate, leading to the formation of α‐ and β‐alkenyl‐BODIPYs. 2‐Phenylacetaldehyde and similar precursors exclusively yield elimination products. These acid‐mediated transformations are valuable alternatives to the well‐established, base‐promoted Knoevenagel condensation protocol that is typically employed in the preparation of BODIPYs with near infrared (NIR)‐shifted absorptions.