Lewis acid-mediated intramolecular addition of silyl enol ethers to internal unactivated alkynes

2001 ◽  
Vol 79 (11) ◽  
pp. 1624-1631 ◽  
Author(s):  
Ken-ichiro Imamura ◽  
Eiji Yoshikawa ◽  
Vladimir Gevorgyan ◽  
Tomoko Sudo ◽  
Naoki Asao ◽  
...  
Keyword(s):  
Lewis Acid ◽  
The Other ◽  
Enol Ethers ◽  
Unsaturated Ketones ◽  
Silyl Enol Ethers ◽  
Other Hand ◽  
High Yields

The EtAlCl2-mediated intramolecular addition of silyl enol ethers to both terminal and internal unactivated alkynes, bearing alkyl and phenyl susbstituents at the alkyne moiety, gave mono- and bicyclic β,γ-unsaturated ketones in good to excellent yields. On the other hand, the silyloxy-substituted cyclic vinylsilanes were obtained in moderate to high yields when the reactions were catalyzed by B(C6F5)3 in the presence of triethylsilane. All the reactions proceeded via endo-fashion exclusively. The mechanisms of these regiospecific Lewis acid-assisted carbocyclizations are proposed.Key words: Lewis acid, silyl enol ethers, carbocyclization, alkynes.

ChemInform Abstract: Lewis-Acid-Induced Reactions of α-Methoxyglycinamide Derivatives with Silyl Enol Ethers. Formation of 3-Amino-2-pyrrolidinones and 3- Amino-2-pyrrolinones.

ChemInform ◽  
2010 ◽  
Vol 23 (48) ◽  
pp. no-no
Author(s):  
E. C. ROOS ◽  
H. HIEMSTRA ◽  
W. N. SPECKAMP ◽  
B. KAPTEIN ◽  
J. KAMPHUIS ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Enol Ethers ◽  
Silyl Enol Ethers

scholarly journals Synthesis of spiro[dihydropyridine-oxindoles] via three-component reaction of arylamine, isatin and cyclopentane-1,3-dione

2013 ◽  
Vol 9 ◽  
pp. 8-14 ◽  
Author(s):  
Yan Sun ◽  
Jing Sun ◽  
Chao-Guo Yan
Keyword(s):  
Acetic Acid ◽  
Reaction Mechanism ◽  
Room Temperature ◽  
The Other ◽  
Other Hand ◽  
Three Component Reaction ◽  
High Yields

A fast and convenient protocol for the synthesis of novel spiro[dihydropyridine-oxindole] derivatives in satisfactory yields was developed by the three-component reactions of arylamine, isatin and cyclopentane-1,3-dione in acetic acid at room temperature. On the other hand the condensation of isatin with two equivalents of cyclopentane-1,3-dione gave 3,3-bis(2-hydroxy-5-oxo-cyclopent-1-enyl)oxindole in high yields. The reaction mechanism and substrate scope of this novel reaction is briefly discussed.

scholarly journals Bifurcated synthesis of methylene-lactone- and methylene-lactam-fused spirolactams via electrophilic amide allylation of γ-phenylthio-functionalized γ-lactams

2020 ◽  
Vol 16 ◽  
pp. 2769-2775
Author(s):  
Tetsuya Sengoku ◽  
Koki Makino ◽  
Ayumi Iijima ◽  
Toshiyasu Inuzuka ◽  
Hidemi Yoda
Keyword(s):  
Hydroxy Group ◽  
The Other ◽  
Synthetic Methods ◽  
Other Hand ◽  
Acidic Conditions ◽  
High Yields

New synthetic methods for spirolactams bearing an α-methylene-γ-butyrolactone or its analogous methylene-lactam have been developed. The allylation of γ-phenylthio-functionalized γ-lactams with 2-(acetoxy)methyl acrylamides was accomplished by using 2.5 equivalents of NaH to give the corresponding adducts in excellent yields. The remaining phenylthio group was substituted with a hydroxy group by treatment with CuBr, and the resulting γ-hydroxyamides were cyclized under acidic conditions to afford the corresponding methylene-lactam-fused spirolactams in high yields. On the other hand, methylene-lactone-fused spirolactams could be delivered from the allyl adducts in high yields through a sequential N-Boc protection/desulfinative lactonization.

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