Methyl exchange on silicon during the addition of methylmagnesium iodide to a cyanohydrin O-silyl ether

1999 ◽  
pp. 431-432 ◽  
Author(s):  
Cécile Arbez-Gindre ◽  
Valérie Berl ◽  
Jean-Pierre Lepoittevin
Keyword(s):  
Silyl Ether ◽  
Methylmagnesium Iodide

ChemInform Abstract: Methyl Exchange on Silicon During the Addition of Methylmagnesium Iodide to a Cyanohydrin O-Silyl Ether.

ChemInform ◽  
2010 ◽  
Vol 30 (26) ◽  
pp. no-no
Author(s):  
Cecile Arbez-Gindre ◽  
Valerie Berl ◽  
Jean-Pierre Lepoittevin
Keyword(s):  
Silyl Ether ◽  
Methylmagnesium Iodide

On the Chemistry of Ingenol, III [1] Synthesis of 3-Deoxy-3-oxoingenol, Some 5-Esters and of Ethers and Acetals of Ingenol

1982 ◽  
Vol 37 (12) ◽  
pp. 1640-1647 ◽  
Author(s):  
Bernd Sorg ◽  
Erich Hecker
Keyword(s):  
Good Yield ◽  
Protecting Groups ◽  
Silyl Ether ◽  
Subsequent Removal ◽  
Mouse Ear

3-Deoxy-3-oxoingenol (3) was prepared from ingenol-5,20-acetonide (25) by oxidation and subsequent removal of the acetonide. 3 was acylated to give homologous 5,20-diacylates 5-9. From these the 5-monoacylates 14, 15 and 17 were obtained in only moderate yields. Therefore the 20-silyl ether 10 (prepared from 3) was acylated. After smooth removal of the silyl ether the homologous 5-acylates 16. 18 and 19 resulted in good yield. The 5,20-dibutyrate 6 and all 5-acylates prepared (14-19) showed no irritant activity on the mouse ear. The 3-oxo-5-acylates 14-19 could not be reduced to give ingenol-5-acylates (24). Therefore various ingenol derivatives, 29-32, with suitable protected hydroxyl functions as well as the corresponding 5-clecanoates 35-38 were synthesized. The protecting groups of the derivatives 35-38 could however not be cleaved off to yield ingenol-5- decanoate (24)

Reductive cleavage mechanism of diphenyl ether and apparent ipso trapping of an intermediate radical anion with a silyl ether

1982 ◽  
Vol 47 (22) ◽  
pp. 4250-4254 ◽  
Author(s):  
Kundanbhai M. Patel ◽  
Richard J. Baltisberger ◽  
Virgil I. Stenberg ◽  
Neil F. Woolsey
Keyword(s):  
Radical Anion ◽  
Diphenyl Ether ◽  
Reductive Cleavage ◽  
Silyl Ether ◽  
Intermediate Radical

ChemInform Abstract: ACTION OF METHYLMAGNESIUM IODIDE ON DIOXOLANONES

1978 ◽  
Vol 9 (7) ◽  
Author(s):  
M. BERCOT ◽  
G. JEANTY ◽  
P. BERCOT
Keyword(s):  
Methylmagnesium Iodide

Silyl ether linkers

2011 ◽  
Vol 3 (2) ◽  
pp. 97-97 ◽  
Author(s):  
Anne Pichon
Keyword(s):  
Silyl Ether

Oxidation of secondary alcohols and ethers by dimethyldioxirane

1999 ◽  
Vol 77 (3) ◽  
pp. 308-312 ◽  
Author(s):  
Alfons L Baumstark ◽  
Franci Kovac ◽  
Pedro C Vasquez
Keyword(s):  
Oxygen Atom ◽  
Methyl Ether ◽  
Radical Pair ◽  
Parent Compound ◽  
Activation Parameters ◽  
Silyl Ether ◽  
Secondary Alcohols ◽  
Benzyl Alcohols ◽  
Oxidation Of Alcohols ◽  
Direct Abstraction

The oxidation of several series of secondary alcohols 2-9, ethers 10-17, and related derivatives 18 and19, by dimethyldioxirane, 1, in acetone at 25°C produced the corresponding ketones in good to excellent yields for all but two cases. (The exceptions: oxidation of 1-methoxy-2-methyl-1-phenylpropane (48%) and 1-methoxy-2,2-dimethyl-1-phenylpropane (24%).) The oxidation of the secondary alcohols was found to yield k2 values that were roughly 10-fold greater than those of the corresponding methyl ethers. The rate constant for oxidation of a silyl ether was slightly lower than that for the corresponding methyl ether while that for the ester derivative was roughly half the value. For oxidation of alcohols and methyl ethers, the k2 values became smaller as the R " series (Me, Et, nPr, iPr, and tBu) increased in steric bulk (ρ* = 1.7; r = 0.998 and ρ* = 3.2; r = 0.95, respectively). The Hammett study for the oxidation of the methyl ethers of α-methyl-p-benzyl alcohols (10, 20-25) yielded a ρ value of -0.74. The activation parameters for oxidation of the parent compound of the ether series (1-methoxy-1-phenylethane) were ΔH‡ = 14.8 ± 0.5 kcal/mol, ΔS‡ = -21.9 eu, ΔG‡ = 21.3 kcal/mol, k2 (25°C) = 1.6 × 10-3 M-1 s-1. The mechanistic aspects of the oxidation are discussed in relation to two mechanistic extremes: (a) direct insertion of the oxygen atom into the C—H bond and (b) direct abstraction of the H by dimethyldioxirane to yield a caged-radical pair, with subsequent coupling to hemi-ketal intermediates that fragment to yield acetone, alcohol or water, and ketone as the final products.Key words: dimethyldioxirane, oxidation.

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