Various systems for the formation of iodo-azide derivatives of alkenes have been examined. Iodine(I) azide, formed from sodium azide-iodine(I) chloride, has been found to exist in acetonitrile as a complex with sodium azide. The addition of iodine(I) azide to 5α-androst-2-ene in both dichloromethane and acetonitrile has been examined in detail, as well as the addition of thallium(I) azide-iodine in dichloromethane to the same substrate. Products were identified as those arising by diaxial opening of either α- or β-iodonium ions, or by cis-addition to the α-face of the alkene. Addition of iodine(I) azide in dichloromethane to 3-methyl-5α-androst-2-ene gave a cis-adduct as the major product, in addition to trans-diaxial adducts and a trans-diequatorial adduct. Formation of the products was rationalised as arising from c-3 carbocations or from trans-diaxial opening of either α- or β-iodonium ions. The major product from the reaction in acetonitrile was one of ring contraction. No cis product was formed in this reaction but an elimination product was present. Products from the latter reaction were postulated as arising from trans-diequatorial or trans-diaxial opening of either α- or β-iodonium ions. The reaction of sodium azide-iodine-crown ether with 3-methyl-5α-androst-2-ene in chloroform gave a high yield of the same product as those obtained in the reaction with iodine(I) azide in acetonitrile. The reaction of thallium(I) azide-iodine in dichloromethane with the above alkene gave products which could have all arisen via a c-3 carbocation. Solvolysis of the trans-iodo-azides of 5α-androst-2-ene with silver(I) acetate in acetic acid occurred with retention of configuration showing that azide acted as a neighbouring group in the reaction. Solvolysis of the trans-iodo-azide(94) of 3-methyl-5α-androst-2-ene gave, inter alia, a product where azide migration had occurred. Solvolysis of the trans-iodo-azide(95) gave mainly products of elimination. The action of iodine(I) azide on 3-methylene-5α-androstane and 1-mewthylene-4-tert-butylcyclohexane was examined and found to be non-regio- and non-stereo-specific. Iodo-azides were also formed from 3-tert-butylcyclohexene and 3-methoxycyclohexene. In each reaction the major product was that of trans-diaxial opening of the cis-iodonium ion, while the second major product arose by trans-diequatorial opening of the trans-iodonium ion. The ratio of diaxial to diequatorial product varied with the iodo-azide-producing system being used, and was larger in the case of 3-methoxy-cyclohexene, especially when the solvent was dichloromethane. A mechanism was postulated which involves reversible formation of iodonium ions as the fast step followed by rate-limiting attack by azide ions. Solvolysis of these iodo-azides was also investigated. Prior to the current work, both an AdE2 and an Ad3 mechanism had been postulated for the addition of iodine(I) azide to alkenes and in an attempt to distinguish between these possibilities a kinetic study was initiated. Preliminary results indicate that the reaction with cyclohexene is electrophilic and second order.

Complexes of tetravalent uranium and thorium have been prepared with the tetradentate ligands N, N’-ethylenebis(salicylaldimine), N,N’-o-phenylenebis(sali-cylaldimine) and the analogous ligands containing substituent groups in the salicylaldimine benzene rings (i.e. 3-MeO, 3-EtO, 5-Cl, 5-NO2). Attempts to form bidentate salicylaldimine complexes were impeded by hydrolysis and oxidation; however, the metal complexes with N-Mesalicylaldimine, N-Etsalicylaldimine and N-phenylsalicylaldimine have been isolated. X-ray powder patterns for these complexes are reported. X-ray structural studies have revealed the salicylaldehyde, N-Mesalicylaldimine, N-Etsalicylaldimine and N,N’-o-phenylenebis(salicylaldimine) complexes of thorium to be eight co-ordinate, with the salicylaldimine complexes having distorted square antiprismatic co-ordination and the salicylaldehyde complex displaying a dodecahedral configuration. U.V., visible and near-I.R. spectra of Schiff-base complexes of thorium, uranium, thallium and lithium are also reported and discussed.

The radiolysis of cysteine in both deaerated and oxygenated solution at pH 7 has been studied. In deaerated solution the mechanism of the reaction appears to be the same as that at pH 5 - 6. The rate constant for the reaction •OH + RSH → RS• + H2O has been measured by competition with paranitrosodimethylaniline. A value of 9 x 109 was found, which though not absolutely accurate (for reasons described in the text) is sufficiently accurate to that the reaction is fast. The rate constant of the reaction eaq + RSH → R• + SH- been measured by competition with oxygen, and a value of (4.0±0.2) 4 x 109 was found. This compares well with values found by other methods. From the values of G(-RSH), G(RSSR), and G(H2O2) in oxygenated solution, and from the effects of the scavengers nitrous oxide and acetone or these values a mechanism has been proposed in which RS radicals produced by attack of primary species on cysteine propagate a chain, the rate of the propagation reaction depending on the cysteine concentration. The autoxidation of cysteine has been studied briefly, the rate being found proportional to oxygen concentration. The mechanism is believed to be the same as that for the radiolysis.

Pauling (1931) introduced the concept of the hybridisation of (n - 1)d, ns and np orbitals to explain the two classes 'ionic' and 'covalent' into which co-ordination compounds of transition metals appeared to fall. These two classes in general have different numbers of unpaired spins, hence they will be distinguished by their magnetic moments. For a series of ferric salts a moment corresponding to either one or five unpaired spins was found, but not intermediate values. I the 'ionic' case the five d-electrons go into the 3d orbitals with their spins parallel giving a moment corresponding to five unpaired spins. I the octahedral case d2 sp3 hybridisation occurs, leaving three d-orbitals to hours the five d-electrons thus giving rise to a moment corresponding to one unpaired spin.

trans-1,2-Dichloro-1,2-dihydronaphthalene has been obtained as the major product of the photochlorination of naphthalene at low temperature, and is the first authentically described naphthalene dichloride. Its further reaction with chlorine, under heterolytic conditions gives, in part, a new naphthalene tetrachloride, whose configuration has been assigned, by 1H n.m.r., as being that of the r-1,c-2,c-3,t-4-isomer. The assigned configuration and conformation of the compound are confirmed by its behaviour on alkaline dehydrochlorination, which gives mainly trans-1,2,4-trichloro-1,2-dihydronaphthalene as an intermediate. The naphthalene dichloride, and its 4-chloro-derivative, have been found to undergo solvolysis in methanol - acetone (4:1), and it is further found that heterolysis of the carbon-chlorine bond at C- 2 is strongly favoured, leading largely to the 1-chloro-substituted elimination product. The former dichloride also gives a small amount of 1-methoxynaphthalene, which is possibly derived by unimolecular substitution at the 1-position. The presence of a chlorine atom at the 3-position of the structure is found to inhibit the solvolytic reaction. Bimolecular syn-elimination in these compounds is accelerated by the presence of additional chlorine substituents, and the increasing preference shown for attack at H- 2, which is further accentuated by the use of the powerfully basic reagent, potassium t-butoxide in t-butanol-dimethylsulphoxide (1:4), is interpreted as indicating a transition state tending toward the E1cB- like side of the E2 spectrum of transition states. The naphthalene tetrachlorides, and some derivatives, have been found to undergo aluminium trichloride-catalysed epimerization at the benzylic centres, which yields information on the relative thermodynamic stabilities of isomers with identical relative configurations at C- 2 and C- 3, and can also be of synthetic value. The photochlorination of 1-chloronaphthalene in CC14 at room temperature proceeds analogously with the reaction of naphthalene under the same conditions, giving five new tetrachlorides, four of which have been thoroughly characterized. The presence, in some tetrachlorides, of inter-ring non-bonded compressions between adjacent chlorines has been found to cause significant changes in the geometry of the alicylic ring, causing a tendency for the half-boat conformation to be adopted, provided this does not lead to 1,4-diaxially related chlorines. The strain present in these compounds is manifested by their very marked tendency to undergo isomerization in the presence of aluminium trichloride, and greatly increased rates of alkaline dehydrochlorination. The chlorination of l,5-dichloronaphthalene in chloroform, or dichloromethane, has been studied and has been found to be markedly catalysed by traces of iodine. The products are almost wholly derived by addition of chlorine in the first stage, and this has been interpreted as arising from a steric inhibition of proton-loss by the adjacent peri-chlorine.

Part I, The Hofmann Rearrangement. First-order rate constants and activation parameters were determined for the rearrangement of eleven N-halogenoamides. The structures of the N-halogenoamides (RCO.NHX) differed in the leaving group (X = chlorine or bromine) and the migrating group (R=ethyl, isopropyl, t-butyl, diphenylmethyl, benzyl, phenyl or p-tolyl). N-Bromoamides and the corresponding N-chloroamides rearranged at similar rates. When the leaving group was changed from bromide to chloride the activation energy was reduced by about one kcal. mole-1 and the activation entropy was reduced by about three cal. deg.-1 mole-1. Differences in the reactivity of halides as leaving groups from carbon and nitrogen are discussed. Changes in the structure of alkyl migrating groups resulted in small irregular changes in the activation parameters. The kinetic data were consistent with a stepwise rearrangement mechanism in which halide departed from nitrogen in the rate-determining step to give a short-lived nitrene intermediate which subsequently rearranged to an isocyanate. Other aspects of the Hofmann rearrangement were investigated. In the Hofmann reaction of amides and hypobromite, N-bromination of the amide was found to be much faster than the rearrangement of the intermediate N-bromoamide conjugate base. In contrast, when amides and hypochlorite reacted in alkaline solution N-chlorination was not fast by comparison with the rearrangement of the intermediate N-chloroamide conjugate base. Oxygen, iodide, and hypobromite did not inhibit the Hofmann rearrangement. Rearrangement of N-brmoacetamide N-bromopropionamide, N-bromoisobutyramide and N-bromopivalamide in the presence of oxygen gave traces of nitrite as a by-product. Nitrite may result from the capture of an intermediate nitrene by oxygen. Ionisation constants of six N-bromoamides and one N-chloroamide were measured. Of the N-halogenoemides which were investigated, the most acidic was N-chloroperfluorobutyramide (pK 2.45) and the least acidic was N-bromopropionamide (pK 7.95). There are no ionisation constants of N-halogenomides recorded in the chemical literature. Part II, The Rearrangement of N-Bromo-α-halogenamides and N-Bromoperhalogenoamides. Previous investigators of the rearrangement concluded that the conjugate base of the N-halogenoamide rearranged intramolecularly via a cyclic four-membered transition state to give an alkyl halide and cyanate ion. This mechanism is incompatible with evidence presented in this thesis. The arrangements of N-bromoperfluorobutyramide and N-bromo-α-chloroisobutyramide in alkaline solution were not first-order reactions. In neutral aqueous solution, the N-halogenoamide conjugate bases did not rearrange. However, in the presence of an excess of hydroxide ion, the N-halogenoamide rearranged readily. The rearrangement was catalysed by hydroxide ion and ammonia and inhibited by many reagents including oxygen, hypobromite, iodide, cupric hydroxide, silver oxide, and amides of carboxylic and sulphonic acids. Possible rearrangement mechanisms are discussed. The effects of small proportions of the inhibitors showed that the rearrangement was a chain reaction. Two probable steps in the chain reaction are the addition of hydroxide ion to the N-halogenoamide conjugate base to give a dianionic intermediate and heterolysis of the nitrogen-bromine bond in this intermediate to give a nitrene. Part III, The Reaction of Mandelamide and Hypohalite. In alkaline solution, mandelamide and hypohalite yield benzaldehyde, cyanate and halide. Several mechanisms which were postulated by previous investigators are excluded by evidence presented in this thesis. Evidence for an N-chloromandelamide intermediate in the reaction of mandelamide and hypochlorite was obtained. Chlorination of mandelamide in neutral or acidic solution gave N-chloromandelamide and N,N-dichloromandelmide. In alkaline solution, the N-chloromandelamides decomposed to give benzaldehyde and cyanate. This reaction was much faster than the reaction of mandelamide and hypochlorite to give the same products. The reactions of hypobromite and hypoiodite with mandelamide were also investigated. Neither oxygen nor an excess of hypobromite inhibited the reaction of mandelamide and hypobromite to give benzaldehyde and cyanate. Hypoiodite (prepared from the reaction of hypochlorite and iodide) and mandelamide also gave benzaldehyde and cyanate in high yield. The mechanism most consistent with the evidence involves the rearrangement of an intermediate N-halogeno-α-hydroxyamide conjugate base to an α-hydroxyalkyl isocyanate which subsequently decomposes to benzaldehyde and cyanate. Mechanisms involving dianionic intermediates were disproved. Stoichiometric similarities in the rearrangements of N-bromo-α-halogenoamides and N-halogeno-α-hydroxyamides were shown to be fortuitous and not the result of similarities in the rearrangement mechanisms. Part IV, Preparation of Amides, N-Bromoamides, and N-Chloroamides. Preparations of amides and N-halogenoamides used in this thesis are described. Some of the N-halogenoamides have not been reported previously. Methods for preparing N-bromo-perhalogenoamides which are described in the chemical literature involve the bromination of the silver salt of the perhalogenoamides in trifluoroacetic acid solution. A much simpler method for preparing N-halogenoperhalogenoamides is described in this thesis.

An amperometric method has been developed for continuous determination of iodine concentrations of the order of 10-5 molar. Catalysis of the bromate-iodide and iodate-iodide reactions by carboxylate and phoshphate ions has been shown to occur. The rates of these reactions may be expressed: -d(BrO⁻₃)/dt = k₀(H⁺)²(I⁻)¹(Br0⁻₃)¹ + kb(B⁻)¹(H⁺)²(I⁻)¹(BrO₃)¹ -d(IO⁻₃)/dt = k₀(H⁺)²(I⁻)²(IO⁻₃)¹ + kb(B⁻)¹(H⁺)²(I⁻)²(IO⁻₃)¹/1 + k'(I⁻)¹ The structure of the iodate ion in solution has been investigated. It has been concluded that the predominant species is the pyramidal IO-3 ion, and any aquated form is present to the extent of no more than one part in 108. Previous studies of halate-halide and related reactions have been reviewed, and mechanisms have been postulated for these reactions on the basis of available information.

This thesis deals with thiocarbonyl complexes of ruthenium and osmium [LnM-CS]. In chapter 1 a comprehensive review of all transition metal thiocarbonyl complexes is presented. Unlike carbon monoxide, carbon monosulphide is a highly reactive molecule which does not exist under normal laboratory conditions. However, transition metal complexes of this reactive intermediate are typically stable compounds of which there are now approximately two hundred reported examples. This small number has made a complete review possible. Slow spasmodic growth has accompanied transition metal thiocarbonyl chemistry since the prototype complex was discovered in 1966 and chapter 1 discusses the synthetic reasons for this, describes critically the current bonding models, and presents the reactions of thiocarbonyl complexes. The very new field of the chemistry of selenocarbonyl complexes [LnM-CSe] is included and comparison with this and with the well-documented chemistry of carbonyl complexes allows for an analysis of periodic changes. The review indicates that CS ligand reactions had received little attention at the outset of this project. Interligand reactions involving CS were unknown primarily because thiocarbonyl complexes containing ligands suitable for investigating reactions of this type had not been synthesised. In particular, transfer of hydrido or aryl ligand to CS had not been observed. Such reactions are the subjects of chapters 3 and 6. The investigation of these transfer reactions necessitated the prior preparation of complexes containing hydrido or aryl ligands cis to the thiocarbonyl ligand. Suitable complexes were synthesised from the very versatile synthetic intermediate OsCl2 (CS) (PPh3)3 [Chapter 3], which was discovered after considerable effort had been devoted to finding high yield routes for introducing the CS ligand into the coordination sphere of ruthenium and osmium [Chapter 2]. Chapter 3 is concerned with hydride transfer to the CS ligand. The thioformyl ligand [OS-C-H-S] results from the transfer of one hydrido ligand to CS and subsequent reactions, which are also probably hydride transfers, produce the thioformaldehyde [Os-S-C-H-H] and methylthiolato [Os-SCH3] ligands. The possible relevance of these ligands as models for postulated intermediates in the Fischer-Tropsch synthesis is noted. The thioformyl and thioformaldehyde ligands were hitherto unknown and the formulations have been additionally verified by investigating the reactivity of these novel ligands and characterising the derivatives obtained. A synthetic route to secondary carbine complexes and to nitrogen and oxygen equivalents of the thioformyl ligand [Os-C-H—NMe and Os-C-H—O] is demonstrated. The review in chapter 1 also recounts how observation has shown that strong σ-donor and strong π-acceptor properties of the CS ligand exert a profound effect upon the reactivity of CS complexes. In particular, strong π-acceptor properties mark the CS ligand as an ideal candidate for stabilising very electron-rich metal centres such as d8 ruthenium(O) or osmium(O). In chapter 4 high yield routes to zerovalent osmium thiocarbonyl complexes are detailed and the reactivity of these complexes is exploited to afford the first high yield syntheses of dithiocarbonyl complexes. The thiocarbonyl ligand is also viewed, from the collected information in chapter 1, as being more responsive to the coordinative environment than the better-known carbonyl ligand. Thus, while CS can remove more electron-density from basic metal centres than CO, CS can also donate more electron-density than CO when coordinated to very electron-poor metal centres. Consequently, it is not surprising that reactions which have been regarded in a classical sense as electrophilic or nucleophilic attack at CO are also found for CS. In chapter 5 several novel reactions which can be described as nucleophilic attack at the CS carbon atom are reported for both neutral and cationic complexes. One such reaction is an interligand reaction of cis thiocarboxamido and thiocarbonyl ligands which affords a four-membered osmium metallocycle. Chapter 6 describes how coordinatively unsaturated aryl-thiocarbonyl-containing complexes react with potentially bidentate anionic ligands to produce coordinatively saturated complexes. coordinative saturation also occurs with carbon monoxide or isocyanide and these latter compounds undergo a rearrangement reaction which involves the thiocarbonyl ligand. Available evidence, which includes the results of an incomplete X-ray crystal structure determination, suggests that a bidentate thioacyl ligand [Os-S-C-R] is produced by transfer of the aryl ligand to CS with ring-closure. Some further reactions of this novel ligand are also discussed. In conclusion, the work reported here extends this research group’s interest in the chemistry of low valent transition metal compounds and the ligands which stabilise such compounds to thiocarbonyl complexes of ruthenium and osmium. The present status of the chemistry of transition metal thiocarbonyl complexes has been examined and the work presented in the experimental chapters contributes to this small area of chemistry by examining, for the first time, interligand reactions which involve CS, by providing synthetic routes to CS complexes of osmium(O), and by beginning to examine the synthetic potential of the novel compounds and ligands obtained.

Copolymerisation of ethyl cellulose (EC) with methyl methacrylate (MMA) and vinyl acetate was carried out in solution, using a number of free radical initiators, to form graft copolymers with grafting yields up to 63% and weight average molecular weight about 9 x 104 g mol-1 Graft copolymerisation of MMA and EC appears to involve participation of comonomer charge transfer complexes at the initial stage of reaction, Interaction of EC with the carbonyl group of MMA enhances the electron-accepting ability of EC and promotes the formation of a donor-acceptor complex as matrix, with the resultant generation of a covalent bonded monomer radical, which then propagates in the usual manner to produce EC-g-PMMA. The influence of a number of experimental variables on the grafting efficiency of the EC-g-PMMA reaction, and the properties of the resulting copolymers, was investigated. The initiator has a significant effect on the grafting efficiency, which decreases in the order azobisisobutyronitril>ammonium persulphate>potassium persulphate>Ce(IV) ion. Benzoyl peroxide was found to be unsuitable because it promoted degradation of ethyl cellulose chains. The order of solvent influence on the grafting yield is chloroform>toluene>benzene. The grafting yield is also reaction time and temperature dependent. A2-3 hour reaction time and 40-50°C reaction temperature gives a substantial increase in both reaction rate and the molecular weight of the graft copolymer product. The introduction of PMMA graft side chains onto EC main chains leads to a significant decrease in the radius of gyration in solution, as determined by size exclusion chromatography, compared to linear EC. This finding is explained by the theory of Stockmayer and Fixman in terms of the number and type of long chain graft points in the molecule, Calculation of viscosity of EC-g-PMMA in solution using the Kurata equation gave values in good agreement with the experimentally determined viscosity. A significant result is that grafting PMMA branches onto EC reduces the hydrodynamic volume, and differential scanning calorimetry showed conclusively that increasing PMMA sidechain length reduces the chain flexibility, by reduction of free volume. The glass transition temperature of EC-g-PMMA, produced by using a large excess of MMA monomer and reasonably long reaction time, was shifted to higher temperature with increase of grafting yield and molecular weight. A single glass transition is observed for copolymers made using low initiator concentrations, and two glass transitions are found for higher initiator concentrations. In addition, EC-g-PMMA samples with higher grafting yield are more brittle than those with lower grafting yield. However, both the bending modulus (determined by dynamic mechanical thermal analysis) and elongation at break increase with grafting yield. Our experiments proved that the crystallinity of EC-g-PMMA is less than that of pure EC and greater than that of pure amorphous PMMA. The specific oxygen gas-permeability coefficients of EC-g-PMMA films decrease with increase of grafting yield. The reason is that grafting decreases of hydrodynamic volume. Interestingly, X-ray diffraction showed that the higher the grafting yields of EC-g-PMMA, the higher its crystallinity. Films of EC-blend-PMMA, made by solution casting and examined in cross section using scanning electron microscopy, showed an essentially multiple layer morphology with non-uniform dispersion of PMMA in the EC matrix. Scanning electron microscopy confirmed, as expected, that EC-g-PMMA cast films were homogeneous with no evidence of phase separation. The tensile strength of EC-g-PMMA films was typically about 20% higher than that of EC-blend-PMMA films, and the graft copolymer films exhibited greater oxygen permeability. A new model for graft copolymerisation to EC is proposed. The model provides for the possibility that grafting to EC with 48% ethoxy content can occur at the five OC2H5 groups and one OH group per unit. It was established using NMR spectrometry of EC-g-PMMA and EC-g-Poly (vinyl acetate) that under some conditions the ethoxy groups are the favoured graft sites. The liquid crystalline properties of EC and EC-g-PMMA were extensively investigated. Optical microscopy with crossed polarisers revealed that the relatively short mesomorphic temperature range of ethyl cellulose is extended downwards almost to ambient temperature in the graft copolymer. Low frequency Raman scattering showed that EC-g-PMMA has higher light scattering intensity than EC at ambient temperature. But it was lower than that of EC at 191°C. Moreover, the Jaynes-Cummings model cannot predict the light scattering intensity of EC-g-PMMA as a function of frequency very well, whereas the EIT-Kerr scheme is able to successfully account for the experimental observations. It was found that EC and EC-g-PMMA are pseudoplastic, lyotropic and thermotropic materials whose viscosity in solution is dependent on many factors, particularly on temperature and solution concentration. Both materials show unusual rheological behaviour, including maxima in the isothermal concentration dependence of viscosity. Unmodified EC exhibits thixotropic flow behaviour, whereas grafting PMMA side chains onto EC changes the flow behaviour to rheopectic, which is also typical of PMMA itself. As the temperature and concentration increase, the viscosity increases in response to the transition from an isotropic to an anisotropic state of EC-g-PMMA. Furthermore, experiments on the distinguishing characteristics of EC-g-PMMA indicate that different solvents affect its anisotropic flow behaviour to a greater or lesser extent. In particular, chloroform shows a stronger flow orientation effect than tetrachloroethane on EC-g-PMMA solutions. The rheological behaviour of EC and EC-g-PMMA in the nematic phase is much more complex than that of ordinary polymers or low molecular weight liquid crystals. The Doi theory is usually applicable to ordinary polymers or low molecular weight liquid crystals, but cannot predict shear stress as a function of shear rate; particularly at very low shear rates for EC and EC-g-PMMA. Whereas, the polydomain model is better to account for the observations. Measurements of thermally stimulated depolarisation current showed that EC-g-PMMA has a longer dipolar relaxation time in an electrical field. Molecular dipole motions of EC give a maximum depolarisation current at 138 °C in the glass transition region and another maximum near 200 °C, corresponding to dipolar relaxation in the liquid crystalline phase. EC-g-PMMA shows a broader dipolar relaxation temperature range in the liquid crystalline phase and the depolarisation current maximum shifts to a lower temperature. We have observed that field induced polarisation of EC-g-PMMA is affected by the length of the PMMA side chain, and obeys an interfacial model of the Maxwell-Wagner-Sillars type. It was confirmed by X-ray photoelectron spectroscopy that the length of the PMMA side chain could affect the surface properties. EC-g-PMMA has higher photoemission intensity than EC, and the photoemission intensity and depolarisation current increase with grafting yield.

This thesis is concerned with the utilisation of the natural product, abieta-8,11,13-trien-18-oic acid* (dehydroabietic acid) (1) for the synthesis of optically active steroids and diterpenoids. The work has been divided into three sections which describe transformations of rings A, B and C of abieta-8,11,13-trien-18-oic acid (1). Selective epoxidation of the alkene mixture (3-5) derived from oxidative decarboxylation of abieta-8,11,13-trien-18-oic acid (1) with lead tetraacetate has given the epoxides (64), (65), a low yield of the epoxide (66), and the pure exocyclic alkene (3). The alkene (3) was oxidised to the ketone (6) which has been previously employed as an intermediate for the synthesis of the α,β-unsaturated ketone (10). The epoxides (64) and (65) have been converted to the unsaturated ketones (89), (107), and (67), and the saturated ketones (13), (99) and (100). A study of the boron triflouride rearrangements of the three epoxides (64), (65) and (66) has been made using benzene and dimethyl suplhoxide as solvents, and pathways for the formation of the products are suggested. Peracid oxidation of the enol acetate (155) derived from the C 7-ketone (18) provided a facile introduction of oxygen substituents into the hindered C 6 position of abieta-8,11,13-trien-18-oic acid (1). By hydrogenolysis of the C 7-hydroxy substituent of the compound (162), the C 6-acetate (172) was obtained. Hydrolysis of the latter compound, and methylation of the acid formed gave the C 6-alcohol (175) which was oxidised to the C 6-ketone (176). The literature pertaining to the intramolecular functionalisation of aromatic alkyl groups has been surveyed, and, with the ultimate aim of synthesizing the aromatic steroids (237) and (249), the C 13-isopropyl group of abieta-8,11-13-trien-18-oic acid (1) has been functionalised by the application of two of the published procedure, viz. the lead tetraacetate oxidation of aromatic acids, and the thermolysis of diaxomethyl ketones. Nitration of methyl 12-acetylabieta-8,11,13-trien-18-oate (227) has given products of nitrodeacylation (44) and nitrodealkylation (266). The product of nitrodealkylation (266) has been converted to methyl 13-hydroxy-podocarpa-8,11,13-trien-18-oate (59) in 36% yield. Methylation of the phenol (59), and Birch reduction of the methyl ether (276) has given podocarp-8(14)-en-18-ol-13-one (281). Annelation of the α,β-unsaturated ketone (281) with bromoacetone was attempted in order to synthesize the steroid (284), but the only product identified was the furan (286). * The numbering system used throughout this thesis is that proposed by J.W. Rose (personal communication to Professor R. C. Cambie) in “The Common and Systematic Nomenclature of Cyclic Diterpenes” 3rd revision, Oct 1968, to be submitted to the IUPAC Commission on Organic Nomenclature.