Boron trifluoride etherate on silica-A modified lewis acid reagent (VII). Antitumor activity of cannabigerol against human oral epitheloid carcinoma cells

1998 ◽  
Vol 21 (3) ◽  
pp. 353-356 ◽  
Author(s):  
Seung Hwa Baek ◽  
Young Ok Kim ◽  
Jung Suk Kwag ◽  
Kyw Eun Choi ◽  
Woo Young Jung ◽  
...  
Keyword(s):  
Antitumor Activity ◽  
Lewis Acid ◽  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
Carcinoma Cells ◽  
Acid Reagent

Stereochemical Aspects of Aldehyde Additions to Cyclohex-2-Enylstannanes

1985 ◽  
Vol 38 (12) ◽  
pp. 1767 ◽  
Author(s):  
D Young ◽  
W Kitching
Keyword(s):  
Lewis Acid ◽  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
Alcohol Formation ◽  
Acid Adduct

Cyclohex-2-enylation of aldehydes, mediated with boron trifluoride etherate, involves γ-equatorial approach of the presumed aldehyde-Lewis acid adduct (RCHO-BF3), irrespective of starting stannane stereochemistry. Marginal threo selectivity characterizes homoallyl alcohol formation from benzaldehyde, whereas alkanals react with high erythro selectivity, so that 1-(1′-hydroxyalkyl)cyclohex-2-enes in this diastereomeric form are available based on allyltin chemistry.

Part 1: Efficient strategies for the construction of variably substituted bicyclo[5.3.1]undecenones (AB taxane ring systems)

2004 ◽  
Vol 82 (2) ◽  
pp. 215-226 ◽  
Author(s):  
Alain Laurent ◽  
Nidia P Villalva-Servín ◽  
Pat Forgione ◽  
Peter D Wilson ◽  
David V Smil ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
Diels Alder ◽  
Ring Systems ◽  
Electronic Nature ◽  
Single Diastereomer ◽  
Cyclic Molecules ◽  
The Cross ◽  
Propargyl Alcohols

Strategies for the construction of cyclic molecules containing variably substituted bicyclo[5.3.1]undecenones (AB taxane ring systems) are described. These routes employ a multi-component coupling protocol that utilizes sequential magnesium-mediated carbometallation of propargyl alcohols and intramolecular Diels–Alder reactions (IMDA). The cycloaddition generates the key eight-membered taxane ring as a single diastereomer, induced by preferential Lewis acid (diethylaluminum chloride or boron trifluoride etherate) complexation with the cross-ring oxygens. Both the electronic nature of the dienophile and the neighbouring group non-bonded interactions contribute to the success of these cycloadditions.Key words: magnesium chelate, Lewis acid, intramolecular Diels–Alder, cycloaddition.

Synthesis and Lewis acid induced isomerization of mono-, di-, and tri-spiro α-keto tetrahydro-furans and -pyrans

2006 ◽  
Vol 84 (10) ◽  
pp. 1388-1396 ◽  
Author(s):  
David G Hilmey ◽  
Peter R Selvaraj ◽  
Leo A Paquette
Keyword(s):  
Lewis Acid ◽  
Ground State ◽  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
Ring Expansion ◽  
Stage Conversion ◽  
Ring Expansions ◽  
Third Stage ◽  
Synthetic Equivalent ◽  
Acid Catalyzed

The stereoselectivity of the acid-catalyzed ring expansion of dihydrofuranyl and dihydropyranyl 1,2-adducts to spirocyclic ketones 8 and 9 has been examined. These substrates have become readily available by the utilization of 1,3-dichloroacetone as a synthetic equivalent of cyclopropanone. The kinetically controlled isomerizations result in ring expansion to dispirocyclopentanones. Third-stage conversion to trispirocyclohexanones was shown to be possible in select examples. On a different front, the syn and anti pairs proved capable of interconversion by heating in the presence of boron trifluoride etherate. A push–pull fragmentation of the ketone ring is proposed to account for these epimerizations. Calculations have been performed to simulate transition state energies in the oxonium ion intermediates and to gain some idea of the preferred ground-state geometries of the final products.Key words: oxonium ion rearrangements, ring expansions, acid-catalyzed epimerizations, cyclopropanone equivalent, spirocyclic ethers.

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