The application of low temperature nuclear magnetic resonance (n. m. r.) spectroscopy to the determination of the barrier heights to interconversion in compounds which contain one and two flexible six-membered rings is reviewed. Although the barrier heights in cyclohexane and its derivatives have been experimentally determined, similar studies in the cis-decalin system have (until very recently) not been successful. Consideration is given, therefore, to the preparation of a number of cis-9, 10-disubstituted decalin derivatives, which will act as model compounds for a further study in the problem of the barrier height to ring interconversion in the cis-decalin system.
Various attempts to synthesize a novel model compound, tricycle [4. 4. 4. 0]
tetradecane, are described. Partial success has been achieved in that a small
but demonstrable amount of tricycle [4. 4.4. 0]-3, 8-tetradecadiene has been
synthesized in a ten step reaction sequence, starting from acetylenedicarboxylic
acid. A Diels-Alder condensation of this compound with two mole-equivalents
of 1, 3-butadiene gave Δ² ⁶-hexalin-9,10-dicarboxylic anhydride. Lithium
aluminum hydride reduction of this compound gave cis-9, 10-bis(hydroxymethyl)-Δ² ⁶
-hexalin, which was converted to its dimesylate derivative on treatment
with methanesulfonyl chloride in pyridine. Reaction of the dimesylate derivative
with sodium cyanide in N-methyl-2-pyrrolidinone gave cis-9, 10-bis(cyanomethyl)-Δ² ⁶-hexalin. Alkaline hydrolysis of the latter gave cis-9,10-bis(carboxymethyl)-Δ² ⁶-hexalin, which was converted to its dimethyl ester on treatment with diazo-
methane in 1, 2-dimethoxyethane. Lithium aluminum hydride reduction of the
dimethyl ester gave cis-9,10-bis(2-hydroxyethyl)Δ² ⁶-hexalin. Treatment of
the dialcohol with methanesulfonyl chloride in pyridine gave cis-9, 10-bis(2-mesyl-oxyethyl)-Δ² ⁶-hexalin. Reaction of the dimesylate with sodium iodide in acetone
gave cis-9, 10-bis(2-iodoethyl)-Δ² ⁶-hexalin. Treatment of this compound with
n-butyllithium in diethyl ether and in heptane gave a mixture of cis-9-ethyl-10-
vinyl-Δ² ⁶-hexalin and tricyclo[4. 4.4. 0]-3, 8-tetradecadiene (minor product). Attempts to improve the yield of the tricyclic compound, using zinc and magnesium as coupling reagents, were unsuccessful.
The syntheses of other desired model compounds are described. Thus,
cis-9, 10-dimethyl-Δ²-octalin and -Δ² ⁶-hexalin were prepared from their cis-
9, 10-bis(mesyloxymethyl)- analogs on treatment of the latter compounds with
sodium iodide in N, N-dimethylformamide, followed by the treatment of the respective
product diiodides with lithium aluminum hydride in 1, 2-dimethoxyethane. cis-9,10-
Dimethyldecalin was prepared from cis-9, 10-dimethyl-Δ² ⁶-hexalin by catalytic
hydrogenation of the latter. In addition, treatment of cis-9, 10-bis(hydroxymethyl)- decalin and -Δ²-octalin with p-toluenesulfonic acid in benzene yielded 12-oxa-
tricycle [4. 4. 3. 0] tridecane and -3-tridecene, respectively. 12-Oxatricyclo [4. 4. 3. 0]
-3, 8-tridecadiene was isolated as a by-product from the reaction of cis-9, 10-bis-
(mesyloxymethyl)-Δ² ⁶-hexalin with sodium cyanide in N-methyl-2-pyrrolidinone, as was 12-amino-11-cyanotricyclo [4. 4. 3. 0]-3, 8, 11-tridecatriene. All of the new compounds have been characterized by means of infrared, ultraviolet, and n. m. r. spectroscopy, mass spectrometry, and microanalysis, where applicable.
Preliminary investigations of the barrier heights to interconversion in cis-9, 10-dimethyldecalin and 12-oxatricyclo [4. 4. 3. 0] tridecane are described. Quantitative kinetic data could not be obtained from the low temperature (0 to -60°) n. m. r. spectra of the former, since no broadening of the ring proton resonance peak was observed. On the other hand, the latter compound gave n. m. r. spectra in which the ether ring proton resonance peak broadened considerably as the sample temperature was lowered. From these spectra a value of the energy of activation (Ea) of 8. 4 ± 2 kcal. /mole was calculated for the interconversion process in 12-oxatricyclo [4. 4. 3. 0] tridecane. / Science, Faculty of / Chemistry, Department of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/37351 |
| Date | January 1965 |
| Creators | Scott, William Bruce |
| Publisher | University of British Columbia |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
Page generated in 0.0058 seconds