Over the past decades, functional group manipulation of aromatic precursors has been a common strategy to access new aromatic compounds. However, these classical methods, such as Friedel-Crafts alkylations and electrophilic/nucleophilic aromatic substitutions, have shown lack of regioselectivity besides the use of activators in excess amounts. To this end, numerous benzannulations to form benzo-fused substrates via Diels-Alder (DA), ring-closing metathesis (RCM), cycloaddition, and transition-metal-promoted processes have been reported. Appending a benzene ring directly onto a pre-existing ring is preferable to many classical methods due to the likely reduction of reaction steps and superior regiocontrol. However, many of these benzannulation reactions require air- and/or moisture- sensitive reaction conditions, a last oxidation step, or the use of highly functionalized precursors. Here we disclose three ‘complementary’ intramolecular ring-opening benzannulations to access a large array of functionalized (hetero)aromatic scaffolds utilizing cyclopropenes-3,3-dicarbonyls, alkylidene cyclopropanes-1,1-diesters, and 2,3-dihydrofuran O,O- and N,O- acetals as building blocks. More than 70 benzo-fused aromatic compounds were synthesized using this complementary approach with yields up to 98% and low catalyst loadings. With these benzannulation reactions in hand, we aim to open the synthetic door to a handful of bioactive natural products.
| Identifer | oai:union.ndltd.org:GATECH/oai:smartech.gatech.edu:1853/54916 |
| Date | 27 May 2016 |
| Creators | Aponte-Guzman, Joel |
| Contributors | France, Stefan |
| Publisher | Georgia Institute of Technology |
| Source Sets | Georgia Tech Electronic Thesis and Dissertation Archive |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation |
| Format | application/pdf |
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