ELECTRONIC EFFECTS AND RATES IN THE DIELS-ALDER REACTION

1952 ◽  
Vol 17 (2) ◽  
pp. 201-206 ◽  
Author(s):  
JOSEPH J. DUDKOWSKI ◽  
ERNEST I. BECKER
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Electronic Effects ◽  
Diels Alder Reaction

The steric course of some electrophilic additions to the tetrahydropyridazine ring moiety of benzo[g]pyridazino[1,2-b]-phthalazine-6, 13-dione derivatives. II.

1997 ◽  
Vol 75 (3) ◽  
pp. 348-355 ◽  
Author(s):  
María Del Carmen Cano ◽  
Fernando Gómez-Contreras ◽  
Ana María Sanz ◽  
María Josefa Rodriguez Yunta
Keyword(s):  
Double Bond ◽  
Alder Reaction ◽  
Diels Alder ◽  
Reaction Products ◽  
Electronic Effects ◽  
Electrophilic Attack ◽  
Diels Alder Reaction ◽  
Pyridazine Ring ◽  
Product Distributions ◽  
Electrophilic Additions

The stereochemical features involved in electrophilic additions to the ring A moiety in diazatetracyclic analogues of anthracyclinones have been investigated. The 1-methyl and 1,3-dimethyl derivatives 2a and 2b were selected as the substrates and made to react with bromine azide, iodine azide, and NBS–EtOH in order to evaluate the influence of the C-1 substituent on the product distributions. Electrophilic attack at the C-2/C-3 double bond occurs mainly in the less hindered anti fashion. The nucleophilic step governs the stereochemistry of the reaction products. Conformational factors are predominant over the steric and electronic effects originated by the ring A substituents, since axial antiparallel attack of the nucleophile on the intermediate epihalonium ion is clearly preferred to the equatorial approach. Keywords: diazatetracycles, Diels–Alder reaction, electrophilic addition, anthracyclinone analogues, pyridazine ring.

scholarly journals Regio- and stereoselective ring openings of unsymmetrical oxatricyclo adducts

1997 ◽  
Vol 75 (6) ◽  
pp. 665-680 ◽  
Author(s):  
Simon Woo ◽  
Masood Parvez ◽  
Brian A. Keay
Keyword(s):  
Ring Opening ◽  
High Selectivity ◽  
Alder Reaction ◽  
Diels Alder ◽  
Grignard Reagents ◽  
Electronic Effects ◽  
Diels Alder Reaction ◽  
Ring Opening Reaction ◽  
Organolithium Reagents ◽  
Ring Opening Reactions

SN2′ ring-opening reactions of a number of substituted 11-oxatricyclo[6.2.1.01,6]undec-9-en-5-ones prepared via the intramolecular Diels–Alder reaction employing a furan diene (IMDAF) are reported. Primary, secondary, and tertiary organolithium reagents were capable of effecting the ring-opening reaction, while methyllithium required activation before any ring opening was observed. Hydride reagents, organocuprates, and Grignard reagents were generally ineffective. The ring-opening reaction was highly regio- and stereoselective for attack at C9syn to the bridging oxygen atom provided that C8 was not substituted. A highly stereoselective nucleophilic addition to the carbonyl group anti to the bridging oxygen was also observed. The high selectivity appears to be due to a combination of steric and electronic effects. Keywords: SN2′ reactions, oxatricyclo adducts, Diels–Alder reaction, ring opening.

The Diels-Alder Reaction of 2-Ethenyl-1,4-Benzodioxin: A New and Simple Synthesis of Bisaryl Ethers

Synlett ◽  
1989 ◽  
Vol 1989 (01) ◽  
pp. 30-32
Author(s):  
Thomas V. Lee ◽  
Alistair J. Leigh ◽  
Christopher B. Chapleo
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Simple Synthesis ◽  
Diels Alder Reaction

The intermolecular anthracene-transfer in a regiospecific antipodal C60 difunctionalization

2020 ◽  
Author(s):  
Radu Talmazan ◽  
Klaus R. Liedl ◽  
Bernhard Kräutler ◽  
Maren Podewitz
Keyword(s):  
Noncovalent Interactions ◽  
Interaction Model ◽  
Alder Reaction ◽  
Diels Alder ◽  
Stacking Interactions ◽  
Pi Stacking ◽  
Diels Alder Reaction ◽  
Double Decker ◽  
Anthracene Molecule ◽  
New Strategies

We analyze the mechanism of the topochemically controlled difunctionalization of C60 and anthracene, where an anthracene molecule is transferred from one C60 monoadduct to another one under exclusive formation of equal amounts of C60 and the difficult to make antipodal C60 bisadduct. Our herein disclosed dispersion corrected DFT studies show the anthracene transfer to take place in a synchronous retro Diels-Alder/Diels-Alder reaction: an anthracene molecule dissociates from one fullerene under formation of an intermediate, while already undergoing stabilizing interactions with both neighboring fullerenes, facilitating the reaction kinetically. In the intermediate, a planar anthracene molecule is sandwiched between two neighboring fullerenes and forms equally strong "double-decker" type pi-pi stacking interactions with both of these fullerenes. Analysis with the distorsion interaction model shows that the anthracene unit of the intermediate is almost planar with minimal distorsions. This analysis sheds light on the existence of noncovalent interactions engaging both faces of a planar polyunsaturated ring and two convex fullerene surfaces in an unprecedented 'inverted sandwich' structure. Hence, it sheds light on new strategies to design functional fullerene based materials.<br>

Natural Products Biosynthesis Involving a Putative Diels-Alder Reaction

2016 ◽  
Vol 20 (22) ◽  
pp. 2421-2442 ◽  
Author(s):  
Kévin Cottet ◽  
Maria Kolympadi ◽  
Dean Markovic ◽  
Marie-Christine Lallemand
Keyword(s):  
Natural Products ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction
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