Surfactant-assisted specific-acid catalysis of Diels–Alder reactions in aqueous media

2007 ◽  
Vol 20 (10) ◽  
pp. 764-770 ◽  
Author(s):  
Egid B. Mubofu ◽  
Jan B.F.N. Engberts
Keyword(s):  
Acid Catalysis ◽  
Aqueous Media ◽  
Diels Alder ◽  
Surfactant Assisted

Intramolecular Diels–Alder Reactions of Oxazoles, Imidazoles, and Thiazoles

Synthesis ◽  
2020 ◽  
Author(s):  
Peter Wipf ◽  
Thanh T. Nguyen
Keyword(s):  
Natural Products ◽  
Lewis Acid ◽  
Acid Catalysis ◽  
Copper Catalysts ◽  
Diels Alder ◽  
Synthetic Approach ◽  
Highly Efficient ◽  
Intramolecular Cycloadditions ◽  
Western Segment ◽  
Target Molecules

AbstractThe development of the intramolecular Diels–Alder cycloaddition­ of azole heterocycles, i.e. oxazoles (IMDAO), imidazoles (IMDAI), and thiazoles (IMDAT), has had a significant impact on the efficient preparation of heterocyclic intermediates and natural products. In particular, highly efficient and versatile IMDAO reactions have been utilized as a key step in several synthetic schemes to provide alkaloids and terpenoid target molecules. More limited studies have been performed on IMDAI and IMDAT cycloadditions. Some drawbacks, such as the occasionally­ challenging preparation of IMDA precursors, are also highlighted in this review. Perspectives are provided on how IMDAI and IMDAT­ transformations can be further expanded for target-directed syntheses.1 Introduction2 Oxazoles2.1 IMDAO Approaches to Furanosesquiterpenes and Furanosteroids2.1.1 Syntheses of Highly Oxygenated Sesquiterpenes2.1.2 Syntheses of (±)-Gnididione and (±)-Isognididione2.1.3 Synthesis of (±)-Stemoamide2.1.4 Synthesis of (±)-Paniculide A2.1.5 Syntheses of (+)- and (–)-Norsecurinine2.1.6 Synthesis of Evodone2.1.7 Syntheses of (±)-Ligularone and (±)-Petasalbine2.1.8 Syntheses of Imerubrine, Isoimerubrine, and Grandirubrine2.1.9 Syntheses of Furanosteroids2.1.10 Syntheses of Substituted Indolines and Tetrahydroquinolines2.2 IMDAO Approaches to Pyridines: the Kondrat’eva Reaction2.2.1 Syntheses of Suaveoline and Norsuaveoline2.2.2 Synthesis of Eupolauramine2.2.3 Syntheses of (–)-Plectrodorine and (+)-Oxerine2.2.4 Synthesis of Amphimedine2.2.5 Synthetic Approach to the Western Segment of Haplophytine2.2.6 Synthesis of Marinoquinoline A2.2.6.1 IMDAO Approach to Marinoquinoline A2.2.6.2 Scope of Allenyl IMDAO Cycloaddition2.3 Lewis Acid Catalysis in IMDAO Reactions2.3.1 Effects of Europium Catalysts on IMDAO Reactions2.3.2 Effects of Copper Catalysts on IMDAO Reactions3 Imidazoles 4 Thiazoles4.1 Syntheses of Menthane and Eremophilane4.2 Further Comments on the Intramolecular Cycloadditions of Thiocarbonyl Ylides5 Conclusions and Outlook

scholarly journals Studies on the transannular Diels–Alder reaction of 15-membered macrocyclic trienes containing a trans-trans diene. Part I: Synthesis and isomerization of various model cyclopentadecatrienes

1995 ◽  
Vol 73 (10) ◽  
pp. 1675-1694 ◽  
Author(s):  
Dennis G. Hall ◽  
Renate Müller ◽  
Pierre Deslongchamps
Keyword(s):  
Aqueous Media ◽  
Alder Reaction ◽  
Membered Ring ◽  
Diels Alder ◽  
Coupling Reactions ◽  
Diels Alder Reaction ◽  
Trans Diene

The transannular Diels–Alder reaction of 15-membered macrocyclic trienes with a trans-trans-cis (TTC) olefin geometry can lead to A.B.C.[6.6.7] tricyclic products of trans-syn-trans (TST) and cis-syn-cis (CSC) stereochemistry whereas the TTT isomers can produce the trans-anti-cis (TAC) and cis-anti-trans (CAT) tricycles. In order to study the influence of the position (pro-6.6 or pro-6.7) and the nature (alkyl, alkoxymethyl, or formyl) of the dienophile substituent, a set of 10 model cyclopentadecatrienes was prepared. The synthesis of appropriately functionalized trisubstituted dienophile and diene synthons, as well as their coupling reactions affording acyclic precursors, is described in this paper (first in a series of two). A mild and efficient macrocyclization protocol yielded the required methyl- or alkoxymethyl-substituted cyclic substrates. Further transformations led to the formyl-substituted ones. In particular, the TTT macrocycles containing an enal as a dienophile could be completely isomerized to the corresponding TTC thermodynamic isomers in acidic aqueous media. Keywords: transannular, Diels–Alder, 15-membered ring, A.B.C.[6.6.7] tricycles, diterpene.

Intramolecular hetero-Diels–Alder reaction of 1-oxa-1,3-butadienes with terminal acetylenes in aqueous media using CuI

Tetrahedron ◽  
2008 ◽  
Vol 64 (48) ◽  
pp. 10924-10929 ◽  
Author(s):  
Malihe Javan Khoshkholgh ◽  
Saeed Balalaie ◽  
Rolf Gleiter ◽  
Frank Rominger
Keyword(s):  
Aqueous Media ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
Terminal Acetylenes

The synthesis, thermochromism, and cycloadditive properties of an O-methylenethioquinone system

1977 ◽  
Vol 55 (21) ◽  
pp. 3763-3773 ◽  
Author(s):  
P. de Mayo ◽  
H. Y. Ng
Keyword(s):  
Thermodynamic Parameters ◽  
Acid Derivative ◽  
Acid Catalysis ◽  
Ion Pair ◽  
Pair Formation ◽  
Membered Ring ◽  
Diels Alder ◽  
Ion Pair Formation ◽  
Thiosalicylic Acid

The irradiation of 4,5-benzo-1,2-dithiole-3-thione (1) in the presence of cyclopentene and of tetramethylethylene gives 1:1 adducts. In solution these adducts are in equilibrium with eight-membered-ring dimers. The thermodynamic parameters for this equilibrium have been determined. The available evidence suggests a head-to-head configuration. These same monomeric adducts give Diels–Alder addition products with normal dienophiles, but also react similarly with simple thiones (adamantanethione, norbornanethione, cyclohexanethione) to give thioorthoesters. The structures of the latter substances have been demonstrated both spectroscopically and, chemically, by hydrolysis to a thiosalicylic acid derivative. The thioorthoesters have been shown to undergo stereoisomerization on acid catalysis. Of the two mechanisms considered for this process (reversal to thiones and ion-pair formation) the former has been excluded.

ChemInform Abstract: Control of Hetero-Diels-Alder Stereoselectivity Through Solvent Polarity and Broensted or Lewis Acid Catalysis; Theory and Experiment.

ChemInform ◽  
2014 ◽  
Vol 45 (12) ◽  
pp. no-no
Author(s):  
Olivier Loiseleur ◽  
Jerome Cassayre ◽  
Dominique Leca ◽  
Francesca Gaggini ◽  
Susan N. Pieniazek ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Acid Catalysis ◽  
Solvent Polarity ◽  
Diels Alder ◽  
Lewis Acid Catalysis ◽  
Theory And Experiment
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