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. 2019 Jul 30;9(41):23652-23657.
doi: 10.1039/c9ra02376c. eCollection 2019 Jul 29.

Iodine-mediated synthesis of benzo[ a]fluorenones from yne-enones

Sikkandarkani Akbar  1 , V John Tamilarasan  1 , Kannupal Srinivasan  1
Affiliations

Iodine-mediated synthesis of benzo[ a]fluorenones from yne-enones

Sikkandarkani Akbar et al. RSC Adv. .

Abstract

The chalcones derived from o-alkynylacetophenones and aromatic aldehydes (yne-enones) when heated under reflux with iodine in acetic acid gave a range of benzo[a]fluorenone derivatives in moderate to good yields. The transformation involves the formation of a vinyl indenone intermediate through regioselective alkyne hydration and intramolecular aldol condensation followed by electrocyclic ring closure and aromatization.

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Conflict of interest statement

There are no conflicts to declare.

Figures

Fig. 1
Fig. 1. Structures of fluostatin natural products.
Scheme 1
Scheme 1. Present synthesis of benzo[a]fluorenones and comparison with literature reports.
Scheme 2
Scheme 2. Preparation of starting materials.
Fig. 2
Fig. 2. X-ray structure of 2b (30% probability level).
Scheme 3
Scheme 3. Control experiments.
Scheme 4
Scheme 4. Proposed mechanism of the reaction.
See this image and copyright information in PMC

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