Browsing by Author "Warren, F L"

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    Insect pheromones : the sex pheromone of Nudaurelia cytherea cytherea Fabr. : (Lepidoptera : Saturniidae)
    (1972) Henderson, Howard Edward; Warren, F L
    Studies leading to the isolation, identification and synthesis of the sex pheromone from the female pine tree emperor moth Nudaurelia cytherea cytherea Fabr. (Lepidoptera : Saturniidae) are described.
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    Insect pheromones : the synthesis of the sex pheromone of Cryptoplebia leucotreta Meyr. and related compounds
    (1969) Henderson, Howard Edward; Warren, F L
    The concept of pheromones is briefly expounded leading on to a discussion of the identified sex pheromones in the order Lepidoptera. The relationship between the structures Of these compounds and their biological activity is reviewed. A brief introduction to the sexual biology of tbe false codling moth (Gryptophlebia Leucotreta Meyr.) is given.
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    Rhizophoraceae alkaloids : an approach to the synthesis of cassipourine
    (1970) Morgan, David Lewis; Warren, F L
    The chemistry and structure of cassipourine are outlined, and a number of various possible synthetic approaches are discussed in the light of the chemistry of 1,2-dithiols and of the pyrrolizidine ring system. A route commencing with L-proline having been chosen, this was converted into l-(p-toluenesulphonyl)-pyrrolizidine-2-aldehyde by protecting the amine with the p-toluenesulphonyl group, esterifying, reducing to the alcohol and then oxidising to the aldehyde. The reduction of the corresponding acid chloride direcl1y to the aldehyde proved less successful. The next step envisaged being the preparation of cis-l-[l'-(p-toluenesulphonyl)-pyrrolidin-2'-yl]-1,2-epoxy-3-benzyloxypropane, a number of routes leading to this compound were attempted. The yield of l-[l'-(p-toluenesulphonyl)-pyrrolidin- 2'-yl]-3-benzyloxy-prop-l-ene, prepared by a Wittig reaction was too low for practical purposes. A novel reaction, the fissioning of the sulphonamide bond by the ylid to give 2- benzyloxyethyl-p-tolylsulphone was noted in this preparation. Attempts to prepare trans-l-[l'-(p-toluenesulphonyl)-pyrrolidin- 2'-yl]-3-benzyloxy-prop-l-ene by reduction of ethyl-3-[1'-(p-toluenesulphonyl)- pyrrolidin-2'-yl]-propenoate followed by benzylation were unsuccessful, as were attempts to prepare the same compound by the allylic rearrangement of l-[l'-(p-toluenesulphonyl)- pyrrolidin-2'-yl]-l-hydroxyprop-2-ene. The cis-epoxide was finally successfully prepared by converting the 1-(p-toluenesulphonyl)-pyrrolidine-2-aldehyde into 3-[l'-(p-toluenesulphonyl)-pyrrolidin-2'-yl]-propenoic acid by a Knoevenagel-Doebner reaction. Brominat1on of the double bond was followed by reduction of the acid to an alcohol, which on treatment with base gave a bromo-epoxide. This was treated with benzyl alcohol to form a benzyloxy-brom-hydrin which gave the required cis-l-[l'-(p-toluenesulphonyl)-pyrrolidin-2'-yl]-1,2-epoxy-3-benzyloxypropane. This sequence of reactions was studied first in a series of model compounds, as were the proposed later stages of the synthesis.
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    Rhizophoraceae alkaloids : preliminary studies in the synthesis of Gerrardine
    (1968) Kleynhans, C R; Warren, F L
    The synthesis envisaged the building of the dithiolane ring on to homoproline, the synthesis of which was effected from tetrahydrofurfuryl alcohol and from proline itself. The reactions involved in these syntheses are discussed with particular reference to the protection of the secondary nitrogen, the difficulties encountered in the application of the Arndt-Eistert reaction, and the possible application of the Prins reaction.
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    Rhizophoraceae alkaloids : studies in the synthesis of Gerrardine
    (1972) Kleynhans, Carl Rudolf; Warren, F L
    Gerrardine, an alkaloid isolated from Cassipourea gerrardii was previously established as 1-methyl-2,5-bis( 4'-hydroxy-1',2'-dithiolan-3'-yl)-pyrrolidine. The aim of the present research was to study the ways in which 1-methyl-2-(4'-hydroxy-1', 2'-dithiolan-3'-yl)-pyrrolidine, as a model compound could be synthesised since it contained asymmetric centres corresponding to those of gerrardine. The work resolved itself into attempts at the synthesis of 3-(1'-methylpyrrolidin-2'-yl)-1,3-dithiolpropan-2-ol since this would be converted into the required dithiolane by mild oxidation.
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    The senecio alkaloids : the correlation of structures with particular reference to senecic acid and its isomers
    (1967) Parazzi, Giovanni; Warren, F L
    Senecic and integerrinecic acid have been assigned structures and on the basis of degradation reactions and X-ray studies. Two isomers arise namely; platynecic and usaramoensenecic actd and are reported in the literature. Their structure as isomers of the senecic and integerrinecic acid structures have been speculated. This thesis is concerned with a study of the isomers of these structures and leads to the conclusion that platynecic and usaramoensenecic acid do not exist and are probably mixtures.