Brønsted Base-Catalyzed Umpolung Intramolecular Cyclization of Alkynyl Imines

2018 ◽  
Vol 24 (16) ◽  
pp. 3998-4001 ◽  
Author(s):  
Azusa Kondoh ◽  
Masahiro Terada
Keyword(s):  
Intramolecular Cyclization ◽  
Brønsted Base

Enantioselective intramolecular cyclization of alkynyl esters catalyzed by a chiral Brønsted base

2016 ◽  
Vol 52 (33) ◽  
pp. 5726-5729 ◽  
Author(s):  
Azusa Kondoh ◽  
Hoa Thi Quynh Tran ◽  
Kyoko Kimura ◽  
Masahiro Terada
Keyword(s):  
Schiff Base ◽  
Intramolecular Cyclization ◽  
Cyclization Reaction ◽  
Base Catalyst ◽  
Chiral Schiff Base ◽  
Brønsted Base

An enantioselective intramolecular cyclization reaction of alkynyl esters was developed, which employs a Brønsted base catalyst generated in situ from a chiral Schiff base and t-BuOK.

Concise Synthesis of GB22 by Endo-Selective Siloxycyclopropane Arylation

2019 ◽  
Author(s):  
Hannah E. Burdge ◽  
Takuya Oguma ◽  
Takahiro Kawajiri ◽  
Ryan Shenvi
Keyword(s):  
Intramolecular Cyclization ◽  
Cross Coupling ◽  
Building Blocks ◽  
Ring Expansion ◽  
Dual Catalysis ◽  
Acid Labile

<div><div><div><p>The first synthesis of GB22 was accomplished by a con- cise, modular route. Two building blocks converged in a novel sp3-sp2 attached-ring coupling that used Ir/Ni dual-catalysis to reverse the regioselectivity of siloxycy- clopropane arylation. This cross-coupling proved general to access β-substituted tetralones via ring-expansion of indanone-derived siloxycyclopropanes. The congested, bridging rings of the GB alkaloids were completed using an aluminum-HFIP complex that effected intramolecular cyclization of an acid-labile substrate.</p></div></div></div>

Concise Synthesis of GB22 by Endo-Selective Siloxycyclopropane Arylation

2019 ◽  
Author(s):  
Hannah E. Burdge ◽  
Takuya Oguma ◽  
Takahiro Kawajiri ◽  
Ryan Shenvi
Keyword(s):  
Intramolecular Cyclization ◽  
Cross Coupling ◽  
Building Blocks ◽  
Ring Expansion ◽  
Dual Catalysis ◽  
Acid Labile

<div><div><div><p>The first synthesis of GB22 was accomplished by a con- cise, modular route. Two building blocks converged in a novel sp3-sp2 attached-ring coupling that used Ir/Ni dual-catalysis to reverse the regioselectivity of siloxycy- clopropane arylation. This cross-coupling proved general to access β-substituted tetralones via ring-expansion of indanone-derived siloxycyclopropanes. The congested, bridging rings of the GB alkaloids were completed using an aluminum-HFIP complex that effected intramolecular cyclization of an acid-labile substrate.</p></div></div></div>

Cyclopropyl→cyclobutyl rearrangement in intramolecular cyclization of 3,5-bridged B-secoandrostane-6,7(or 5,7)-diols and mass spectra of products

1982 ◽  
Vol 47 (8) ◽  
pp. 2280-2290 ◽  
Author(s):  
Helena Velgová ◽  
Jorga Smolíková ◽  
Antonín Trka ◽  
Antonín Vítek
Keyword(s):  
Intramolecular Cyclization ◽  
Mass Spectra ◽  
Acid Catalyzed

Acid-catalyzed intramolecular cyclization of 6,7-dihydroxy-3α,5-cyclo-6,7-seco-5α-androstan-17-one (VII), 5,7-dihydroxy-3,5-methylene-5,7-secoandrostan-17-one and 5,7-dihydroxy-3β,5-cyclo-5,7-seco-A-homo-5β-androstan-17-one (XIII) in benzene and dioxane was investigated. The main cyclization products were 3,5-methylene-6-oxaandrostan-17-one (I) and/or 3β,5-cyclo-6-oxa-A-homo-5β-androstan-17-one (VIII). In the case of VI and VII the ratio of I and VIII was solvent-dependent: in benzene more VIII was formed than in dioxane. The mass spectra of I and VIII were almost identical and corresponded to the structure VIII.

ChemInform Abstract: INTRAMOLECULAR CYCLIZATION IN REACTIONS OF BICYCLIC DIEPOXIDES WITH DIMETHYLAMINE

1985 ◽  
Vol 16 (9) ◽  
Author(s):  
L. I. KAS'YAN ◽  
N. S. ZEFIROV ◽  
N. V. STEPANOVA ◽  
L. E. SALTYKOVA ◽  
O. L. RYZHIK
Keyword(s):  
Intramolecular Cyclization

scholarly journals Easily accessible non-aromatic heterocycles with handles: 4-Bromo-2,3-dihydrofurans from 1,2-dibromohomoallylic alcohols

2021 ◽  
Author(s):  
Jason An ◽  
Jose Intano ◽  
Alissa Richard ◽  
Taehyun Kim ◽  
Jose Gascon ◽  
...  
Keyword(s):  
Intramolecular Cyclization ◽  
Aromatic Heterocycles

The first general preparation of 4-bromo-2,3-dihydrofurans is reported. These non-aromatic heterocyles containing a useful coupling handle are accessed via Cu-catalyzed intramolecular cyclization of 1,2-dibromohomoallylic alcohols, which are themselves available in...

Facile intramolecular cyclization of an olefinic grignard reagent

1966 ◽  
Vol 7 (36) ◽  
pp. 4297-4301 ◽  
Author(s):  
Herman G. Richey ◽  
Thomas C. Rees
Keyword(s):  
Intramolecular Cyclization ◽  
Grignard Reagent

CF3SOCl-Promoted Intramolecular Cyclization of β-Diketones: An Efficient Synthesis of Flavones

Tetrahedron ◽  
2021 ◽  
pp. 132226
Author(s):  
Dong-Wei Sun ◽  
Yong-Yan Zhou ◽  
Min Jiang ◽  
Tang Nian ◽  
Jin-Tao Liu
Keyword(s):  
Intramolecular Cyclization ◽  
Efficient Synthesis
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