REARRANGEMENT STUDIES WITH C14: IX. THE FORMOLYSIS OF METHYL-C14-ISOPROPYLCARBINYL p-TOLUENESULPHONATE

1960 ◽  
Vol 38 (6) ◽  
pp. 787-792
Author(s):  
A. J. Finlayson ◽  
C. C. Lee
Keyword(s):  
Acetic Acid ◽  
Liquid Chromatography ◽  
Formic Acid ◽  
Substitution Reaction ◽  
Gas Liquid Chromatography ◽  
Neighboring Group ◽  
Group Participation ◽  
Neighboring Group Participation ◽  
Reflux Temperature

Formolysis of methyl-C14-isopropylcarbinyl p-toluenesulphonate (I) at reflux temperature gave a mixture of 2-methyl-2-butene (II), 2-methyl-1-butene (III), and 3-methyl-l-butene (IV). The relative amounts of olefins II, III, IV were measured by gas-liquid chromatography to be 88%, 11%, and 1%, respectively. When the formolysis was carried out at 50 °C, besides olefins II, III, and IV, some t-amyl formate was obtained indicating a substitution reaction with neighboring hydrogen participation. Degradation of the mixture of olefins from formolysis gave, among other compounds, radioactive acetone, indicating an isotope position rearrangement in the chief product, 2-methyl-2-butene (II). This rearrangement may be attributed to a 1,2-methyl shift in one of the processes that gave rise to olefin II. A comparison of the data from the acetolysis and the formolysis of I showed that in the E1 reactions, neighboring hydrogen participation is predominant in either solvent. For a change of solvent from acetic acid to the more ionizing formic acid, it was demonstrated that there is a greater degree of neighboring methyl participation while the process involving no neighboring group participation assumes less importance.

REARRANGEMENT STUDIES WITH C14: VII. THE ACETOLYSIS OF METHYL-C14-ISOPROPYLCARBINYL p-TOLUENESULPHONATE

1959 ◽  
Vol 37 (5) ◽  
pp. 940-952 ◽  
Author(s):  
A. J. Finlayson ◽  
C. C. Lee
Keyword(s):  
Liquid Chromatography ◽  
Amyl Acetate ◽  
Gas Liquid Chromatography ◽  
Dilution Technique ◽  
Substitution Product ◽  
Neighboring Group ◽  
Isotope Dilution Technique ◽  
Group Participation ◽  
Neighboring Group Participation ◽  
Reflux Temperature

Acetolysis of methyl-C14-isopropylcarbinyl p-toluenesulphonate (I) at reflux temperature gave a mixture of 2-methyl-2-butene (II), 2-methyl-1-butene (III), and 3-methyl-1-butene (IV) with no isolatable quantity of substitution product. The relative amounts of olefins II, III, and IV were measured by gas–liquid chromatography to be 80%, 18%, and 2%, respectively, and these were substantially verified by estimations with the isotope dilution technique. When the acetolysis was carried out at 50 °C, besides olefins II, III, and IV, present in relative amounts of 83%, 16%, and 1%, respectively, as determined by gas–liquid chromatography, a small quantity of substitution product, t-amyl acetate (V), was obtained. Under the conditions of acetolysis at reflux temperature, however, V was found to decompose to olefins II and III. Degradation of the olefinic products of acetolysis gave, among other compounds, radioactive acetone. Since acetone was derived from the chief product, II, its activity could be attributed to an isotope position rearrangement resulting from a 1,2-methide shift as one of the processes that gave rise to olefin II. This rearrangement amounted to about 2.5% and 0.9%, respectively, in olefin II from acetolysis at reflux temperature and at 50 °C. Considering all these results, it may be concluded that both substitution and elimination reactions could take place during acetolysis of I. The substitution reaction proceeded with neighboring hydrogen participation to yield t-amyl acetate, which would decompose to olefins II and III at reflux temperature under the acetolysis conditions. In the E1 reaction during acetolysis of I, processes involving no neighboring group participation to give olefins II and IV, with neighboring hydrogen participation to give olefins II and III, and with neighboring methyl participation to give isotopically rearranged olefins II and IV, all occurred, the process with neighboring hydrogen participation being predominant.

Differentiation of Actinomyces propionicus from Actinomyces israelii and Actinomyces naeslundii by gas chromatography

1968 ◽  
Vol 14 (7) ◽  
pp. 749-753 ◽  
Author(s):  
Yu-Ying F. Li ◽  
Lucille K. Georg
Keyword(s):  
Gas Chromatography ◽  
Acetic Acid ◽  
Lactic Acid ◽  
Liquid Chromatography ◽  
Formic Acid ◽  
The Other ◽  
Gas Liquid Chromatography ◽  
Actinomyces Naeslundii ◽  
Actinomyces Species ◽  
End Products

Gas–liquid chromatography (g.l.c.) was used for the analysis of certain metabolic end products of Actinomyces propionicus, as an aid in the separation of this organism from the morphologically similar Actinomyces species, A. israelii and A. naeslundii. Profiles of the chromatograms for the major volatile acids of five strains of A. propionicus studied were found to be distinct from those of four strains of A. israelii and four strains of A. naeslundii. The ratio of propionic acid to acetic acid was approximately 50 times as great for A. propionicus as for the other Actinomyces species. Formic acid was present in significant amounts in both A. israelii and A. naeslundii, but was present only in trace amounts in A. propionicus.Two major nonvolatile acids, lactic and succinic, were identified for the A. israelii and A. naeslundii strains. One of the A. propionicus strains also showed both acids in significant amounts; however, the other four strains of A. propionicus showed succinic acid in large amounts, but only trace amounts of lactic acid.

Synthesis of 14-deoxy-14α-strophanthidin

1980 ◽  
Vol 45 (11) ◽  
pp. 2998-3007 ◽  
Author(s):  
Pavel Kočovský
Keyword(s):  
Acetic Acid ◽  
Hydroxy Group ◽  
Cyclic Ether ◽  
Hydroxy Derivative ◽  
Neighboring Group ◽  
Step Process ◽  
Group Participation ◽  
Hypobromous Acid ◽  
Characteristic Features ◽  
Neighboring Group Participation

A seventeen step synthesis of 3β,5-dihydroxy-19-oxo-5β,14α-card-20(22)-enolide (II, title compound) from 3β-benzoyloxy-5-pregnen-20-one (IV) is described. Characteristic features of this approach are the protection of the 19-hydroxy group as methyl ether, recovery of the hydroxyl and the introduction of 5β-hydroxyl on the basis of neighboring group participation. The 19-hydroxy group was regenerated in XIV by a two-step process: Addition of hypobromous acid to the 5,6-double bond leads to the 5α,6α-bromonium ion XV, which is cleaved with 5(O)n participation of the 19-methoxyl group to the cyclic ether XVI, the latter being converted to the 19-hydroxy derivative XVII by treatment with zinc and acetic acid. The 5β-hydroxy group was introduced by hypobromous acid addition to the 5,6-unsaturated 19-formate XVIII which proceeds with 6(O)π,n participation of the formate group (XVIII → XIX → XX).

Neighboring group participation in hypobromous acid addition to 19-substituted 5α-cholest-1-enes and in acid cleavage of their epoxy analogs

1982 ◽  
Vol 47 (11) ◽  
pp. 3062-3076 ◽  
Author(s):  
Václav Černý ◽  
Pavel Kočovský
Keyword(s):  
Neighboring Group ◽  
Group Participation ◽  
Acid Addition ◽  
Acid Cleavage ◽  
Hypobromous Acid ◽  
Neighboring Group Participation

Reactions of the title compounds (bearing an OH, OCH3 or OCOCH3 group at C(19)) involve 5(O)n, 7(O)π,n-participation by the 19-substituent or attack by an external nucleophile. The 6(O)π,n-participation does not occur. The behavior of 1,2-unsaturated (or epoxidated) compounds has been compared with the earlier described 2,3-unsaturated or epoxidated analogs. The 1,2-type is genarally less prone to participation. The reasons for this behavior are discussed.

Mechanism of acid cleavage of some steroid epoxides. Competition between neighboring group participation and external nucleophile attack

1982 ◽  
Vol 47 (1) ◽  
pp. 124-129 ◽  
Author(s):  
Pavel Kočovský ◽  
František Tureček ◽  
Václav Černý
Keyword(s):  
Perchloric Acid ◽  
Cyclic Ether ◽  
Oxirane Ring ◽  
Neighboring Group ◽  
Group Participation ◽  
Acid Cleavage ◽  
Neighboring Group Participation

The mechanism of perchloric acid cleavage of epoxides I and II was established on the basis of experiments using H2 18O. The 2α,3α-epoxide I gave two products: the cyclic ether V (60%) arising by 5(O)n participation of the 19-acetoxyl and the diol VI (40%). The latter compound is formed by two mechanisms: 1) By direct cleavage of the oxirane ring with H2 18O as external nucleophile and 2) by 7(O)π,n participation via the ion III. Under the same conditions the 5α,6α-epoxide II yielded two diols: The diequatorial diol VIII (96%) arising by 6(O)π,n participation and the diaxial diol IX which is again formed by both direct cleavage of the oxirane ring with H2 18O and by 7(O)π,n participation via the intermediate ion X. The competition of several mechanisms is discussed.

ChemInform Abstract: Remote Asymmetric Induction Using Neighboring Group Participation of a Sulfenyl Group.

ChemInform ◽  
2010 ◽  
Vol 25 (49) ◽  
pp. no-no
Author(s):  
Y. HASHIMOTO ◽  
Y. SATO ◽  
N. TAKESHITA ◽  
K. KUDO ◽  
K. SAIGO
Keyword(s):  
Asymmetric Induction ◽  
Neighboring Group ◽  
Group Participation ◽  
Neighboring Group Participation
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