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SYNTHETIC AND MECHANISTIC STUDY OF ENANTIO- AND STEREOSELECTIVE HOUSE–MEINWALD REARRANGEMENT OF CONGESTED TRISUBSTITUTED SPIRO-EPOXIDES

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Date Issued:
2019
Abstract/Description:
Published Content: Jeedimalla, N.; Jacquet, C.; Bahneva, D.; Youte Tendoung, J.-J.; Roche, S. P. J. Org. Chem. 2018, 83, 12357. The present thesis will be focused on the study of House-Meinwald Rearrangement (HMR) reactions for the congested trisubstituted spiro-epoxide molecules. Including their regio-selective, chemo-selective, enantio- selective selective and stereo-selectivity’s will be discussed in detailed by the mechanistic study approach of HMR reaction of trisubstituted spiro-epoxides. Chapter 1 will present the efforts towards the biomimetic total synthesis of meroterpenoid natural product (+)-liphagal, which possess a recognizable biological activity. The shortcomings associated with its stereochemical assignment, and also the revision of stereochemical assignment of siphonodictyal B, through which the biosynthesis of (+)-liphagal was proposed were discussed. Chapter 2 will focus on the study of regio and chemoselective HMR reaction. In addition, a three-step sequence for the synthesis of α-arylated cyclohexanones and the most challenging cycloheptanones is reported. First, an efficient one-pot synthesis of β, β’-disubstituted benzylidene cycloalkanes using the palladium-catalyzed Barluenga reaction from readily available feedstock chemicals is described. Second, an epoxidation followed by the HMR of spiro-epoxides is reported to produce a number of α -arylated cycloalkanones upon the ring expansion. Reactions catalyzed by bismuth triflate underwent quasi-exclusively ring expansion for all substrates (electronically poor and rich), demonstrating the difficulty to achieve the ring enlargement for electron deficient spiro-epoxides. On the other hand, via catalysis with aluminium trichloride the rearrangement proceeded typically in high yields and with remarkable regioselectivity. In this case, a switch of regioselectivity was achieved for spiro-epoxides with electron-withdrawing substituents which enabled this method to be successfully extended to some chemo specific arene shifts and it can also synthesize aldehydes derivatives bearing a α-quaternary carbon.
Title: SYNTHETIC AND MECHANISTIC STUDY OF ENANTIO- AND STEREOSELECTIVE HOUSE–MEINWALD REARRANGEMENT OF CONGESTED TRISUBSTITUTED SPIRO-EPOXIDES.
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Name(s): Jeedimalla, Nagalakshmi, author
Roche, Stephane P., Thesis advisor
Florida Atlantic University, Degree grantor
Charles E. Schmidt College of Science
Department of Chemistry and Biochemistry
Type of Resource: text
Genre: Electronic Thesis Or Dissertation
Date Created: 2019
Date Issued: 2019
Publisher: Florida Atlantic University
Place of Publication: Boca Raton, Fla.
Physical Form: application/pdf
Extent: 225 p.
Language(s): English
Abstract/Description: Published Content: Jeedimalla, N.; Jacquet, C.; Bahneva, D.; Youte Tendoung, J.-J.; Roche, S. P. J. Org. Chem. 2018, 83, 12357. The present thesis will be focused on the study of House-Meinwald Rearrangement (HMR) reactions for the congested trisubstituted spiro-epoxide molecules. Including their regio-selective, chemo-selective, enantio- selective selective and stereo-selectivity’s will be discussed in detailed by the mechanistic study approach of HMR reaction of trisubstituted spiro-epoxides. Chapter 1 will present the efforts towards the biomimetic total synthesis of meroterpenoid natural product (+)-liphagal, which possess a recognizable biological activity. The shortcomings associated with its stereochemical assignment, and also the revision of stereochemical assignment of siphonodictyal B, through which the biosynthesis of (+)-liphagal was proposed were discussed. Chapter 2 will focus on the study of regio and chemoselective HMR reaction. In addition, a three-step sequence for the synthesis of α-arylated cyclohexanones and the most challenging cycloheptanones is reported. First, an efficient one-pot synthesis of β, β’-disubstituted benzylidene cycloalkanes using the palladium-catalyzed Barluenga reaction from readily available feedstock chemicals is described. Second, an epoxidation followed by the HMR of spiro-epoxides is reported to produce a number of α -arylated cycloalkanones upon the ring expansion. Reactions catalyzed by bismuth triflate underwent quasi-exclusively ring expansion for all substrates (electronically poor and rich), demonstrating the difficulty to achieve the ring enlargement for electron deficient spiro-epoxides. On the other hand, via catalysis with aluminium trichloride the rearrangement proceeded typically in high yields and with remarkable regioselectivity. In this case, a switch of regioselectivity was achieved for spiro-epoxides with electron-withdrawing substituents which enabled this method to be successfully extended to some chemo specific arene shifts and it can also synthesize aldehydes derivatives bearing a α-quaternary carbon.
Identifier: FA00013320 (IID)
Degree granted: Dissertation (Ph.D.)--Florida Atlantic University, 2019.
Collection: FAU Electronic Theses and Dissertations Collection
Note(s): Includes bibliography.
Subject(s): Epoxy compounds
Epoxides
Biomimetic Materials--chemical synthesis
Held by: Florida Atlantic University Libraries
Sublocation: Digital Library
Persistent Link to This Record: http://purl.flvc.org/fau/fd/FA00013320
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Host Institution: FAU
Is Part of Series: Florida Atlantic University Digital Library Collections.