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Shekhar C, Satyanarayana G. Acid-Promoted Domino Access to Substituted Benzo[ b]carbazoles. J Org Chem 2024; 89:3732-3746. [PMID: 38394776 DOI: 10.1021/acs.joc.3c02483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2024]
Abstract
Herein, a straightforward Bro̷nsted acids-promoted domino pathway to build substituted benzo[b]carbazoles has been described from easily accessible ortho-formyl (or ortho-acyl) cinnamate esters and indoles. Noticeably, the protocol was amenable to protecting group-free indoles. Notably, this methodology is based on a single-pot regioselective construction of two new C-C bonds and aromatization sequences under mild and metal-free reaction conditions. The mechanistic studies suggested the initial formation of bis-indole substituted intermediate via a dual aromatic substitution with two indole molecules at the carbonyl carbon of ortho-formyl (or ortho-acyl) cinnamate ester followed by intramolecular cyclization and aromatization with exclusion of a second indole molecule. Besides, the efficacy of this approach was also illustrated by scale-up and derivatization reactions, including the photophysical properties study.
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Affiliation(s)
- Chander Shekhar
- Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502 284d, India
| | - Gedu Satyanarayana
- Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502 284d, India
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Orukotan WE, Palate KY, Pogrányi B, Bobinski P, Epton RG, Duff L, Whitwood AC, Grogan G, Lynam JM, Unsworth WP. Divergent Cascade Ring-Expansion Reactions of Acryloyl Imides. Chemistry 2024; 30:e202303270. [PMID: 37987097 DOI: 10.1002/chem.202303270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 11/16/2023] [Accepted: 11/21/2023] [Indexed: 11/22/2023]
Abstract
Macrocyclic and medium-sized ring ketones, lactones and lactams can all be made from common acryloyl imide starting materials through divergent, one-pot cascade ring-expansion reactions. Following either conjugate addition with an amine or nitromethane, or osmium(VIII)-catalysed dihydoxylation, rearrangement through a four-atom ring expansion takes place spontaneously to form the ring expanded products. A second ring expansion can also be performed following a second iteration of imide formation and alkene functionalisation/ring expansion. In the dihydroxylation series, three- or four-atom ring expansion can be performed selectively, depending on whether the reaction is under kinetic or thermodynamic control.
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Affiliation(s)
- Will E Orukotan
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | | | - Balázs Pogrányi
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | - Philipp Bobinski
- Organisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Ryan G Epton
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | - Lee Duff
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | | | - Gideon Grogan
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | - Jason M Lynam
- Department of Chemistry, University of York, York, YO10 5DD, UK
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