Synthesis of (±)-trixagol by an electrophilic cyclization of an allylsilane

1983 ◽  
Vol 61 (11) ◽  
pp. 2530-2539 ◽  
Author(s):  
Rosemary J. Armstrong ◽  
Larry Weiler
Keyword(s):  
Lewis Acids ◽  
Electrophilic Cyclization ◽  
Trimethylsilyl Group ◽  
Monocyclic Compound

1,5-Dienes containing an allylsilane are cyclized by Lewis acids to methylenecyclohexanes. The trimethylsilyl group exerts a strong activating and directing influence on the regioselectivity of this cyclization. The monocyclic compound 10 was converted into the diterpene, (±)-trixagol (3).[Formula: see text]

Synthesis of (±)-albicanyl acetate and (±)-isodrimenin by the electrophilic cyclization of olefinic allylsilanes

1986 ◽  
Vol 64 (5) ◽  
pp. 1002-1006 ◽  
Author(s):  
Rosemary J. Armstrong ◽  
Francis L. Harris ◽  
Larry Weiler
Keyword(s):  
Lewis Acids ◽  
Electrophilic Cyclization

The allylsilane 3 was synthesized and cyclized with Lewis acids or mercuric trifluoroacetate to give 5 or 6, which were converted into albicanyl acetate (7) and isodrimenin (12).[Formula: see text]

scholarly journals Electrophilic Cyclization of Diterpenoids

2006 ◽  
Vol 1 (1) ◽  
pp. 22-35
Author(s):  
Veaceslav Kulciţki ◽  
Marina Grinco ◽  
Pavel Vlad ◽  
Nicon Ungur
Keyword(s):  
Lewis Acids ◽  
Electrophilic Cyclization ◽  
Cyclization Reactions ◽  
Practical Utility ◽  
Electrophilic Reagents

A review of diterpenoid cyclization initiated by electrophilic reagents is provided. Conventional protonic and Lewis acids are examined along with superacids as initiators of cyclization cascade. An emphasis is placed on the use of cyclization reactions as a tool for the synthesis of compounds with potential practical utility. The review contains 74 references.

Synthesis of (±)-karahana ether and a (±)-labdadienoic acid by the electrophilic cyclization of epoxy allylsilanes

1986 ◽  
Vol 64 (3) ◽  
pp. 584-596 ◽  
Author(s):  
Rosemary J. Armstrong ◽  
Larry Weiler
Keyword(s):  
Good Yield ◽  
Lewis Acids ◽  
Electrophilic Cyclization ◽  
Keto Esters

The epoxy allysilanes 7 and 16 were synthesized by stereoselective routes from β-keto esters and cyclized with Lewis acids in good yield. The monocyclic product from 7 was converted into (±)-karahana ether (10), and the bicyclic product from 20 was used in a synthesis of the 3-hydroxylabdadienoic acid 24b.[Formula: see text]

Synthesis of Novel Bis-pyrazoles via Electrophilic Cyclization

2019 ◽  
Vol 16 (6) ◽  
pp. 511-516
Author(s):  
Adnan Cetin
Keyword(s):  
13C Nmr ◽  
Cyclization Reaction ◽  
Electrophilic Cyclization ◽  
Pyrazole Derivatives ◽  
Spectral Analyses ◽  
Mass Spectral ◽  
Palladium Catalyzed ◽  
Ft Ir ◽  
Reaction Compound

Efficient steps towards the synthesis of novel (phenyl)(1'-aryl-1,5,5'-triphenyl[3,3'-bi-1Hpyrazol]- 4-yl)methanones 4a-e were developed. The procedure starts from 1-(4-benzoyl-1,5-diphenyl- 1H-3-pyrazolyl)-3-phenyl-2-propyn-1-one (2) which was synthesized by a palladium catalyzed crosscoupling reaction. Compound 2 reacted with various hydrazines to give (E)-(phenyl)[1,5-diphenyl-3- [3-phenyl-1-(2-arylhydrazono)-2-propyn-1-yl]-1H-4-pyrazolyl]methanones E-3a-e. The bis-pyrazole derivatives 4a-e were synthesized from electrophilic cyclization reaction of α,β-acetylenic hydrazones E-3a-e and copper(I) iodide. All synthesized compounds were characterized by FT-IR, 1H, 13C NMR and Mass spectral analyses.

Catalytic activity of rhodium(I) complexes containing (ω-trimethylsilylalkyl)diphenylphosphines

1980 ◽  
Vol 45 (8) ◽  
pp. 2219-2223 ◽  
Author(s):  
Marie Jakoubková ◽  
Martin Čapka
Keyword(s):  
Catalytic Activity ◽  
Nmr Spectroscopy ◽  
Ir Spectroscopy ◽  
Electron Density ◽  
Phosphorus Atom ◽  
Proton Acceptor ◽  
Trimethylsilyl Group ◽  
Kinetics Of

Kinetics of homogenous hydrogenation of 1-heptene catalysed by rhodium(I) complexes prepared in situ from μ,μ'-dichloro-bis(cyclooctenerhodium) and phosphines of the type RP(C6H5)2 (R = -CH3, -(CH2)nSi(CH3)3; n = 1-4) have been studied. The substitution of the ligands by the trimethylsilyl group was found to increase significantly the catalytic activity of the complexes. The results are discussed in relation to the electron density on the phosphorus atom determined by 31P NMR spectroscopy and to its proton acceptor ability determined by IR spectroscopy.

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