Date: June 10th 2019 (Monday)
Time: 4 PM
Venue: Committee Room (MS710), Chemistry Department, 6th Floor
Abstract: [4+2] Annulation of stabilized phthalide anions as 1,4-dipolar synthons with various Michael acceptors leading to benzannulated quinones, especially naphthoquinones, is popularly known as Hauser-Kraus (H-K) reaction. This reaction involving Michael addition followed by Dieckmann cyclization and elimination provided access to complex molecules, including natural products. Although several Michael acceptors have been successfully employed in this reaction, nitroalkenes have not received sufficient attention.
In the above scenario, we reported the Hauser-Kraus annulation of sulfonylphthalides with nitroalkenes and other electron deficient alkenes. This involved a strategic variation of the reaction to [4+4] annulation by employing nitroalkenes bearing an additional nucleophilic site resulting in complex fused and spiro-heterocycles. In another approach, synthesis of aminophenanthrenes, including phenanthrene substituted amino acids, and benzoquinolines has been achieved using nitroalkenes bearing a key ketoalkyl moiety. A one-pot construction of functionalized spiro-dihydronaphthoquinone-oxindoles via Hauser-Kraus annulation of sulfonylphthalide with 3-alkylideneoxindoles has also been reported by us. Details of these results and further developments will be discussed during the presentation.