X-Ray Diffraction Studies of Caryophyllene Derivatives and Some Other Molecules

Hannaway, Christine (1971) X-Ray Diffraction Studies of Caryophyllene Derivatives and Some Other Molecules. PhD thesis, University of Glasgow.

Abstract

This thesis is divided into four parts. Part I is concerned with a brief account of some of the methods used in X-ray crystallography. The remaining parts describe the application of these methods in determining the crystal structures of six molecules. Part II contains descriptions of the structural analyses of two caryophyllene rearrangement products. The first, the dibromo derivative of 1,5,9,9-tetramethyltricyclo-[6,2,1,O4,11] undec-5-ene, is a product of the acid-catalysed rearrangement of isocaryophyllene. The structure of this molecule was of considerable interest in view of the number of rearrangement products already derived from caryophyllene itself. The second, the dibromo derivative of 2,6,10,10-tetrame thyltricyclo [7, 2,0, 0 2.7] undec-5-ene, is the main product obtained from the dehydrochlorination of caryophyllene dihydrochloride. For many years attempts had been made to identify this compound but without success. The absolute stereochemistries of both derivatives have been established by means of Bijvoet's anomalous dispersion method. Fairly detailed accounts of the conformations of these molecules are given as well as discussions on how the molecules are distorted in order to relieve the strain associated with these species in their classical conformations. Suggestions and comparisons are given in regard to their mechanisms of formation. Part III describes the structural analyses of three natural products. The first molecule to be discussed is the methiodide derivative of the O-acetyl of a homomorphinene alkaloid isolated from the plant Colonicum cornigerum. Spectroscopic and biogene tic arguments could not distinguish between two possible structure solutions whereas the X-ray structure analysis was able to do this and establish the absolute configuration. The second of these natural products to be discussed is pancuronium bromide (3alpha,17beta-diacetoxy-2beta,16beta-dipiperidino-5alpha-androstane dimethobromide), a steroid used as a neuromuscular blocking agent. The crystal structure was determined using the water : methylene chloride solvate and a fairly detailed account of the molecular geometry is given since the high potency and specificity of action of the agent may be associated with this and the rigidity of the molecule. The last of this group of compounds is (+)trans-chrysanthemic acid. The structure analysis of the p-bromo-anilide derivative of this molecule was carried out in order to establish the absolute configuration which had already been reported on the basis of the usual chemical-type correlations. However, chrysanthemic acid is of great importance in terpene correlations and an independent determination of the absolute stereochemistry was desirable and this was carried out using Bijvoet's anomalous dispersion method. The fourth and final part gives an account of the structure determination of di-mu-phenylthio-bis(cyclopenta-dienylcarbonyliron) at -160

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Organic chemistry
• Date of Award: 1971
• Depositing User: Enlighten Team
• Unique ID: glathesis:1971-78565
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 28 Feb 2020 12:09
• Last Modified: 28 Feb 2020 12:09
• URI: https://theses.gla.ac.uk/id/eprint/78565