The reactivity of 3-Ethenyl-4-methylcyclohex-2-en-1-one and related compounds towards some carbanionic nucleophiles

1984 ◽  
Vol 37 (11) ◽  
pp. 2305 ◽  
Author(s):  
RFC Brown ◽  
GL Burge ◽  
DJ Collins
Keyword(s):  
Silica Gel ◽  
Lewis Acid ◽  
Michael Addition ◽  
Acid Catalysis ◽  
Main Product ◽  
Addition Product ◽  
Butyl Alcohol ◽  
Similar Reaction ◽  
Keto Ester ◽  
Related Compounds

The reaction of 3-ethenyl-4-methylcyclohex-2-en-1-one (4) with 2-methylcyclopentane-1,3-dione in refluxing toluene containing pyridine gave 6% of 9bξ-hydroxy-3a,6-dimethyl-3a,4,5,6,7,9b-hexahydro-1H-benz[e]indene-3,9(2H,8H)-dione (10). When the same reactants were heated at 100-110� (sealed tube) in benzene containing t-butyl alcohol and diethylamine the main product (61%) was 5',6-dimethylspiro[bicyclo[3.2.1]octane-1,2'-cyclohexane]-3,6',8'-trione (11); the yield of (11) was 72% when the reaction was carried out in the presence of silica gel. Attempts to effect a similar reaction of the dienone (4) with methyl 1β-t-butoxy-7aβ-methyl-5-oxo-1,2,3,3aα,4β,6,7,7a-octahydro-indene-4-carboxylate (21a) gave no conjugate Michael addition product, but (21a) underwent aminolysis to the corresponding diethylamide (21b). Attempts to alkylate the t-butoxy β-keto ester (21a) under various conditions with 7-acetyloxy-7-ethenyl-8 ξ methyl-1,4-dioxaspiro[4,5]decane (41) failed. Similarly, attempts to effect alkylation of the anion of the t-butoxy keto ester (21a) with 7-ethenyl-8-methyl-1,4-dioxaspiro[4,5]dec-6-ene (43) under Lewis acid catalysis were also unsuccessful.

scholarly journals Studies on the interaction of isocyanides with imines: reaction scope and mechanistic variations

2014 ◽  
Vol 10 ◽  
pp. 12-17 ◽  
Author(s):  
Ouldouz Ghashghaei ◽  
Consiglia Annamaria Manna ◽  
Esther Vicente-García ◽  
Marc Revés ◽  
Rodolfo Lavilla
Keyword(s):  
Double Bond ◽  
Lewis Acid ◽  
Acid Catalysis ◽  
Main Product ◽  
Structural Features ◽  
Ring System ◽  
Membered Ring ◽  
Sequential Process ◽  
Lewis Acid Catalysis ◽  
Nitrogen Double Bond

The interaction of imines with isocyanides has been studied. The main product results from a sequential process involving the attack of two units of isocyanide, under Lewis acid catalysis, upon the carbon–nitrogen double bond of the imine to form the 4-membered ring system. The scope of the reaction regarding the imine and isocyanide ranges has been determined, and also some mechanistic variations and structural features have been described.

Cobalt/Lewis Acid Catalysis for Hydrocarbofunctionalization of Alkynes via Cooperative C–H Activation

2020 ◽  
Author(s):  
Chang-Sheng Wang ◽  
Sabrina Monaco ◽  
Anh Ngoc Thai ◽  
Md. Shafiqur Rahman ◽  
Chen Wang ◽  
...  
Keyword(s):  
Catalytic System ◽  
Lewis Acid ◽  
Hydrogen Transfer ◽  
Acid Catalysis ◽  
Rate Limiting Step ◽  
Site Selectivity ◽  
Set Up ◽  
Site Selective ◽  
First Time ◽  
Rate Limiting

A catalytic system comprised of a cobalt-diphosphine complex and a Lewis acid (LA) such as AlMe3 has been found to promote hydrocarbofunctionalization reactions of alkynes with Lewis basic and electron-deficient substrates such as formamides, pyridones, pyridines, and azole derivatives through site-selective C-H activation. Compared with known Ni/LA catalytic system for analogous transformations, the present catalytic system not only feature convenient set up using inexpensive and bench-stable precatalyst and ligand such as Co(acac)3 and 1,3-bis(diphenylphosphino)propane (dppp), but also display distinct site-selectivity toward C-H activation of pyridone and pyridine derivatives. In particular, a completely C4-selective alkenylation of pyridine has been achieved for the first time. Mechanistic stidies including DFT calculations on the Co/Al-catalyzed addition of formamide to alkyne have suggested that the reaction involves cleavage of the carbamoyl C-H bond as the rate-limiting step, which proceeds through a ligand-to-ligand hydrogen transfer (LLHT) mechanism leading to an alkyl(carbamoyl)cobalt intermediate.

l-Prolinal Dithioacetal: A Highly Effective Organocatalyst for the Direct Nitro-Michael Addition to Selected Cyclic and Aromatic Ketones

Synthesis ◽  
2019 ◽  
Vol 51 (17) ◽  
pp. 3356-3368
Author(s):  
Piotr Pomarański ◽  
Zbigniew Czarnocki
Keyword(s):  
Michael Addition ◽  
Ring Size ◽  
Cyclic Ketones ◽  
Asymmetric Syntheses ◽  
Aromatic Ketones ◽  
Ring Systems ◽  
Effective Catalyst ◽  
Acetophenone Derivatives ◽  
Highly Effective ◽  
Related Compounds

The synthesis of novel l-prolinal dithioacetal and its application as an organocatalyst for the direct Michael addition of cyclic ketones and acetophenone derivatives to trans-β-nitrostyrene and related compounds is described. The prolinal dithioacetal acts as effective catalyst in the case of cyclic ketones of different ring size, in particular five- and six-membered examples, as well as larger and smaller ring systems. High enantioselectivity and diastereoselectivity is observed for different substrates and trans-β-nitrostyrenes. Also, the first asymmetric syntheses of selected 2-methyl-4-nitro-1,3-diphenylbutan-1-one derivatives by application of the obtained organocatalyst is presented.

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

Chiral Lewis Acid Catalysis in Nitrile Oxide Cycloadditions

2004 ◽  
Vol 126 (17) ◽  
pp. 5366-5367 ◽  
Author(s):  
Mukund P. Sibi ◽  
Kennosuke Itoh ◽  
Craig P. Jasperse
Keyword(s):  
Lewis Acid ◽  
Acid Catalysis ◽  
Nitrile Oxide ◽  
Lewis Acid Catalysis ◽  
Chiral Lewis Acid
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