Heterogeneous acid-catalyzed (2,5) oxonium-ene reaction for eight-membered ring formation

2001 ◽  
Vol 42 (39) ◽  
pp. 6859-6863 ◽  
Author(s):  
Hirofumi Ohmura ◽  
Koichi Mikami
Keyword(s):  
Membered Ring ◽  
Ring Formation ◽  
Ene Reaction ◽  
Acid Catalyzed

Dispersion-Controlled Regioselective Acid-Catalyzed Intramolecular Hydroarylation of cis-Methindolylstyrenes to Access Tetrahydrobenzo[cd]indoles

2018 ◽  
Author(s):  
Xiao Cai ◽  
Anargul Tohti ◽  
Cristian Ramirez ◽  
Hassan Harb ◽  
Hrant Hratchian ◽  
...  
Keyword(s):  
Membered Ring ◽  
Ring Formation ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brönsted Acid ◽  
Acid Catalyzed

Readily prepared <i>cis</i>-<i>β</i>-(<i>α</i>’,<i>α</i>’-dimethyl)-4’-methindolylstyrenes undergo Brønsted acid-catalyzed intramolecular hydroarylation to afford a variety of 3-aryl-5,5-dimethyl-1,3,4,5-tetrahydrobenzo[<i>cd</i>]indoles. Our experimental and computational investigations suggest that dispersive interactions between the indole and styrene preorganize substrates such that 6-membered ring formation occurs via a concerted hydroarylation step. When dispersability is attenuated (by a substituent or heteroatom), regioselectivity erodes and competing oligomerization predominates for <i>cis</i> substrates; all <i>trans</i>-configured substrates that we evaluated failed to cyclize efficiently.

Dispersion-Controlled Regioselective Acid-Catalyzed Intramolecular Hydroarylation of cis-Methindolylstyrenes to Access Tetrahydrobenzo[cd]indoles

2018 ◽  
Author(s):  
Xiao Cai ◽  
Anargul Tohti ◽  
Cristian Ramirez ◽  
Hassan Harb ◽  
Hrant Hratchian ◽  
...  
Keyword(s):  
Membered Ring ◽  
Ring Formation ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brönsted Acid ◽  
Acid Catalyzed

Readily prepared <i>cis</i>-<i>β</i>-(<i>α</i>’,<i>α</i>’-dimethyl)-4’-methindolylstyrenes undergo Brønsted acid-catalyzed intramolecular hydroarylation to afford a variety of 3-aryl-5,5-dimethyl-1,3,4,5-tetrahydrobenzo[<i>cd</i>]indoles. Our experimental and computational investigations suggest that dispersive interactions between the indole and styrene preorganize substrates such that 6-membered ring formation occurs via a concerted hydroarylation step. When dispersability is attenuated (by a substituent or heteroatom), regioselectivity erodes and competing oligomerization predominates for <i>cis</i> substrates; all <i>trans</i>-configured substrates that we evaluated failed to cyclize efficiently.

Acid Catalyzed a-Pyrone Ring Formation Reactions

Heterocycles ◽  
1994 ◽  
Vol 37 (3) ◽  
pp. 1705 ◽  
Author(s):  
Okan Tarhan ◽  
Cihangir Tanyeli ◽  
Ayhan S. Demir ◽  
�demir �arslan ◽  
Idris Mecidoglu
Keyword(s):  
Ring Formation ◽  
Pyrone Ring ◽  
Acid Catalyzed

Ring formation via β-keto ester dianions

1977 ◽  
Vol 55 (6) ◽  
pp. 996-1000 ◽  
Author(s):  
Phaik-Eng Sum ◽  
Larry Weiler
Keyword(s):  
Membered Ring ◽  
Ring Formation ◽  
Methyl Acetoacetate ◽  
Keto Ester ◽  
Keto Esters

The reaction of α,ω-dihalides with the dianion of methyl acetoacetate gives a mixture of mono- and bisalkylated products. The monoalkylated products can be cyclized via the monoanion to cyclic β-keto esters with a seven- or eight-membered ring. Alternatively these monoalkylated products can be cyclized via the dianion to γ-cyclopentyl- or γ-cyclohexyl-β-keto esters.

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