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Carbocation Catalysis: Oxa-Diels-Alder Reactions of Unactivated Aldehydes and Simple Dienes
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Sohag University, Egypt.
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.ORCID iD: 0000-0003-1933-4193
2015 (English)In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 30, p. 6610-6614Article in journal (Refereed) Published
Abstract [en]

The versatility of the trityl cation (TrBF<inf>4</inf>) as a highly efficient Lewis acid organocatalyst is demonstrated in the oxa-Diels-Alder reaction of various unactivated aromatic and aliphatic aldehydes and simple unactivated dienes, such as isoprene and 2,3-dimethylbutadiene. The transformation proceeds smoothly to give 3,6-dihydropyrane adducts in high to moderate yields with catalyst loadings down to 1.0 mol-% under mild reaction conditions. In contrast to most previously reported strategies, this protocol does not require substrate functional group activation, neither by electron-deficient aldehydes (2-oxo aldehydes) or electron-rich dienes (methoxy or amino-butadiene).

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2015. no 30, p. 6610-6614
Keywords [en]
Carbocations, Cycloaddition, Organocatalysis, Trityl ion
National Category
Organic Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-175061DOI: 10.1002/ejoc.201501112ISI: 000363339600005Scopus ID: 2-s2.0-84945478847OAI: oai:DiVA.org:kth-175061DiVA, id: diva2:881626
Note

QC 20151211

Available from: 2015-12-11 Created: 2015-10-09 Last updated: 2018-09-26Bibliographically approved
In thesis
1. Carbocation Catalysis for Organic Synthesis
Open this publication in new window or tab >>Carbocation Catalysis for Organic Synthesis
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The most common view of carbocations in organic chemistry is that they are short-lived intermediates in several fundamental reactions, e.g. the classic SN1-reaction. However, carbocations that can delocalize their positive charge can be stable enough to be isolated and used as Lewis acid catalysts, phase transfer catalysts or oxidants in various reactions. The theme of this thesis concerns applying trityl cations as Lewis acid catalysts in different organic reactions. The first chapter presents a general introduction of the field of Lewis acids, the characteristics and applications of carbocations in different organic reactions, and the aims of this thesis. The second chapter describes the carbocation-catalyzed asymmetric Diels–Alder reactions assisted by chiral counteranions. The third chapter shows that carbocations can be utilized as catalysts in oxa-Diels–Alder reactions with unactivated aldehydes and dienes as substrates. The fourth chapter investigates the application of carbocation catalysis in bromination reactions for selective functionalization at the benzylic position and on the aromatic ring, respectively. The fifth chapter highlights that carbocation-catalyzed aldehyde–olefin metathesis reactions can be achieved in high yields by suppressing the decomposition of both starting materials and products.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2018. p. 54
Series
TRITA-CBH-FOU ; 2018:44
Keywords
carbocation, trityl cation, Lewis acid catalyst, enantioselective, chiral counteranion, oxa-Diels–Alder, bromination, aldehyde–olefin metathesis
National Category
Organic Chemistry
Research subject
Chemistry
Identifiers
urn:nbn:se:kth:diva-235422 (URN)978-91-7729-966-0 (ISBN)
Public defence
2018-10-26, F3, Lindstedtsvägen 26, Stockholm, 14:00 (English)
Opponent
Supervisors
Note

QC 20180926

Available from: 2018-09-26 Created: 2018-09-26 Last updated: 2018-09-26Bibliographically approved

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