Browsing by Author "Emslie, Neville Desmond."
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Item An approach to the synthesis of chiral carbamates.(1996) Lea, Kathryn M.; Emslie, Neville Desmond.; Drewes, Siegfried Ernst.An attempt to obtain chiral induction across the carbamate linkage (-NCOO-), using chiral amines and the benzyl carbamate, was embarked upon. Initial studies centred around the benzyl carbamate protected form of a,a-diphenylpyrrolidinemethanol. The inability to protect the alcohol in this compound led to further investigations into differently structured molecules, these being 2-(1-phenylcyc1opentyl)-4,4,6-trimethyltetrahydro-l,3-oxazine and N-biphenyl benzyl carbamate. Chiral induction was not achieved, but the investigations therein led to two new fields of study. A trans-carbamation type cyclisation reaction was found to occur in the a,a-diphenyl-(2pyrrolidine- N-benzyl carbamate)methanol compound yielding the bicyclic 2-oxazolidone, 3-oxa-l-aza-4,4-diphenylbicyclo[3.3.0]octan-2-one, with nitrogen at the bridgehead position. Sodium hydride was the base used to facilitate this reaction. Further studies into this reaction and this class of compounds were inconclusive. The second field of study was the initial investigation into novel N-monosubstituted carbamate rearrangement reactions to yield a substituted alcohol, of the benzyl alcohol type. The rearrangement occurs when the carbamate is treated with butyllithium at O°C and the reaction allowed to warm to room temperature. The rearrangement was shown to occur when the substituent on the nitrogen is aromatic in nature, this group being able to contain a hetero-atom and be substituted. A positive result was also obtained when the 0-carbamate moiety was the benzyl or cinnamyl group and to a much lesser degree the allyl group. The products obtained from the rearrangement of the benzyl carbamates were a-aryl- a-phenylmethanols (substituted benzyl alcohols / benzhydrols), with the analogous product, l-aryl-3-phenylprop-2-en-l-ol, being obtained from the cinnamyl alcohol. A benzylic substituted benzyl carbamate rearranged to give the tertiary alcohol. It was found that the rearrangement occurred to the position on the aryl substituent to which the nitrogen had been attached. From the results obtained no conclusive mechanistic details could be determined, but it was proposed that the reaction intermediate contained a five-membered cyclic structure. It is assumed that the rearrangement occurs with concomitant loss of cyanic acid (HNCO).Item The Carbamate group: migrational and leaving properties: towards the synthesis of flavenes.(1996) Mahabir, Sanjay.; Emslie, Neville Desmond.; Bartels-Rahm, Birgit.Abstract available in PDF.Item Citizens of the nation, citizens of the world? : a comparative content analysis of globalisation in SABC 3 and e-TV national television news.(2007) Emslie, Neville Desmond.; Teer-Tomaselli, Ruth Elizabeth.South Africa is a country interconnected with Africa and also more connected with the world.South African national television news evidently is also more global or 'glocalised' (Robertson, 1996) today in comparison to the period during apartheid. This research incorporates an analytic-empirical, social constructivist approach, and interprets news as a specific construction of reality, a "social artifact" (Hjarvard, 2002: 91) of the context in which it is produced (Venter, 2001: 197). This definition allows for the analysis of existing aspects in news items to determine exactly what makes news reality global, 'glocal' or cosmopolitan.The methodology uses a comparative content analysis of three non-sequential weeks selected during September, October, and November 2006, of SABC 3 and e-TV national television news, focusing only on the first fifteen minutes of bulletins, and examining only foreign news. Foreign news includes foreign news locally and news with a South African connection abroad (Sreberny-Mohammadi etal, 1985). The current research analyses the influence of globalisation on each broadcaster - economically, politically, culturally, and technologically - and examines the mediation of global, 'glocal', and moderate cosmopolitan perspectives in news items. Findings reveal that globalisation does influence SABC 3 and e-TV in similar ways with slight differences, and while national or international perspectives are more prominent, global, 'glocal', and moderate cosmopolitan outlooks are still present, and e-TV represents these slightly more than SABC 3. Conclusively, SABC 3 and e-TV construct its news audience as citizens of the nation and citizens of the world, by representing a 'sliding scale' (Wallis and Baran, 1990) from national to international and global perspectives. This present study demonstrates how SABC 3 and e-TV mediate "allegiances to the outer circle" (Bowden, 2003: 242-243) - regional, international, and global - by examining the relevance of extending beyond a South African perspective in news broadcasts.Item The functionalisation of thenyl carbamates.(1996) Grimmer, Craig Douglas.; Emslie, Neville Desmond.; Bartels-Rahm, Birgit.The carbamate functionality has always been associated with a major class of biocides because of its ability to function as an inhibitor of the enzyme acetylcholinetransferase. However, carbamates are not limited to pesticidal applications, they have also shown potential as intermediates in organic synthesis. Research has shown that amongst its other properties, the carbamate group has the ability to migrate, function as a leaving group and participate in rearrangement reactions. As part of ongoing research at this department on the synthetic utility of the carbamate group, this project has been primarily concerned with the chemistry of carbamates in conjunction with thiophene, an aromatic heterocycle. The thiophenes also represent an important class of organic compounds. They are found in natural products, biologically and pharmacologically active systems (both naturally occurring and synthetic), synthetic precursors and more recently, organic conductors and electro-optical devices. In exploring the chemistry of thiophene carbamates, the unique nature of the thiophene ring has been shown to affect the synthesis and reactions of these compounds; the often peculiar character of thiophene imparts properties which make these carbamates remarkable and distinct from carbamates of other aromatic and conjugated systems such as benzene and conjugated polyenes. With a wide range of potential applications, the purpose of this project has been to study the synthesis and reactions of thiophene carbamates, in particular, the reaction of deprotonated thenyl carbamates with electrophiles, using the electrophile as a means of studying the charge delocalisation in such systems. A series of thenyl carbamates has been synthesised from thenyl alcohols and their reactions with electrophiles have been studied. The electrophilic substitution reactions illustrate the possibilities for the functionalisation of these compounds, particularly remote functionalisation via anionic charge migration; the charge has been found to migrate across five carbon atoms, a phenomenon not observed in this department's studies of other carbamate systems. The substitution products which form in these reactions depend on the nature of both the carbamate and the electrophile. In addition, three rearrangements (carbamate to amine, substituted carbamate to alkene, and substituted carbamate to a-hydroxyamide) have been observed which may find application in organic synthesis. The potential uses for these carbamates range from biologically active applications as carbamates or as derivatives (amines or alkenes via rearrangement or alcohols via deprotection); many contain a chiral centre and thus may be used in enantioselective or diastereoselective processes in the synthesis of other products, as well as the industrial applications in the fields of non-linear optics and conducting polymers.Item Oxidation of primary alcohols to aldehydes and esters.(1998) Mosia, Mamoeletsi Rachel.; Emslie, Neville Desmond.The initial aim of this research project was to oxidise Cr C4 alcohols to their respective aldehydes. However, isolation of these aldehydes was impossible due to their low boiling points. Another problem was the proximity of the boiling points of these aldehydes with the boiling points of solvents used in reactions. As a result, the alcohols investigated in this project were changed to C4-C6 alcohols. Different oxidising reagents are known that oxidise oxidise primary alcohols to aldehydes. Of these, chromium (VI) has been used the most. In this project, Chromium (VI) supported on different inert: inorganic supports was chosen as the oxidising reagent. The first task was therefore to synthesise these supported oxidants. The synthesis of some of these oxidants was lengthy. This is advantage the preparation of supported oxidants. Unsupported oxidants like PCC and chromium trioxide were only used as a basis of comparison to emphasise the usefulness of supported oxidants. Pyridinium chlorochromate was used to oxidise primary alcohols to aldehydes in moderate yields. The reaction was found to be moisture sensitive. The yield and the duration of the reaction was found to be better with the use of molecular sieves. Silica gel-supported pyridinium chromate was also used to oxidise alcohols to aldehydes in good yields. Poly[vinyl(pyridinium chlorochromate)] was used to oxidise I-hexanol and I-pentanol to their respective aldehydes also in good yields. The duration of these reactions ranged from 30 min. to 3 days. During the oxidation of alcohols using silica gel-supported chromium trioxide and diethyI ether/chromium trioxide it was found that the reaction conditions can be changed so that either aldehydes or symmetrical esters were the products. This was achieved by varying the duration of the reaction. Silica gel-supported chromium trioxide resulted in both the aldehydes and esters in good yields while the diethyl iii Aluminium-supported chromium trioxide, kieselguhr-supported chromic acid, alumium silicate-supported chromic acid and alumina-supported pyridinium chlorochromate were used to oxidise primary alcohols to symmetrical and unsymmetrical esters in good to excellent yields. The duration of these reactions varied from 1 hour to 48 hours depending on the conditions employed and the chain length of the reagents.Item Palladium catalysed oxidation of a-olefins to ketones.(1997) Khuzwayo, Bonakele G.; Emslie, Neville Desmond.; Rahm, Birgit.The aim of this research project was to investigate the oxidation reactions of olefins to ketones. Initial studies revolved around the oxidation reactions of terminal olefins to symmetrical dialkyl ketones. The inability to isolate pure products, and the consumption of large amounts of the expensive palladium catalyst for each run as well as the extremely low yields that resulted from these oxidation reactions, made it difficult to thoroughly investigate this oxidation system. It was then decided to embark on the investigation of oxidation reactions of a-olefins to methyl ketones. For these studies, six terminal olefins were oxidised to methyl ketones employing seven different oxidation reactions. One of the most important and pioneering reactions m this field is the system employing PdCl2 / CuCl2 / O2 for the oxidation of terminal olefins to methyl ketones, namely the Wacker oxidation reaction. Experimental results, however, indicated that high product contamination from by-products resulted from these oxidation reactions despite the fairly good yields of product from the Wacker oxidation system. Some reaction systems that have been developed from the Wacker oxidation system were also investigated. The oxidation system employing PdCl2 / p-benzoquinone for the oxidation of terminal olefins to ketones was studied. The oxidation reactions resulted in incomplete oxidation with higher olefins (l-decene, l-nonene and l-octene), and complete oxidation of lower olefins (l-heptene, l-hexene and l-pentene) under the same reaction conditions. The products from lower olefins oxidised under these reaction conditions were pure and high yielding Another system that proved efficient both with feasibility and good yields of products was the oxidation system employing Pd(OAc)2 / H202 catalyst to oxidise terminal olefins to methyl ketones. Phase transfer catalysis has been employed in organic chemistry to effect different reactions. In this case two types of phase transfer agents were employed to effect the oxidation of terminal olefins to ketones. The first oxidation system involved the use of a PdCl2 / CuCl2 / O2 catalyst with a quaternary ammonium salt, cetyltrimethylammonium bromide (CTAB), to govern the course of the reaction. Reasonable yields were obtained, and moderate purity of products was also observed. The second phase transfer catalysis system employed polyethylene glycol (PEG-200) as a phase transfer agent, and PdCl2 / CuCl2 / O2 as a catalyst for oxidation of olefins to ketones. This oxidation system resulted in different isomers of a ketone from a terminal olefin. Pure methyl ketones were not isolable from the mixture of methyl and ethyl ketones. The oxidation reactions of olefins to ketones employing Pd(OAc)2 / p-benzoquinone in combination with electrolysis were also investigated. The unique feature about these reactions was the fact that cyclic olefins could also be oxidised under these conditions. Good yields were obtained, and high product purity was observed. One of the important oxidation reactions investigated during the project was the reaction that used an alternative metal to the expensive palladium catalyst for the oxidation reactions to ketones. This oxidation system employs CuCl2 / 18-C-6 / acetaldehyde as a catalyst for the oxidation of hydrocarbons to ketones and alcohols. It was discovered during the investigation that olefins can also be used as substrates and are oxidised to the corresponding ketones. The use of olefins as substrates resulted in higher yields than the hydrocarbon oxidation reactions, and less contamination in the product mixture was also observed.Item Progress towards the stereoselective synthesis of Warburganal.(1998) Paulton, Anne-Mary.; Emslie, Neville Desmond.; Gravestock, David.The aim of the project was to synthesize warburganal, a natural product isolated from the Warburgia plants native to Venda, known as a potent molluscicide, in a new, cheaper and more efficient way to be used in the ongoing war against bilharzia. A synthetic pathway beginning with geraniol as the starting material was planned to afford a 7-step route. The first step involved the substitution of a bromine group for a hydroxyl group. Geranyl bromide underwent an alkylation step with the dianion of methyl acetoacetate to afford methyl 3-oxo-7, II-dimethyldodeca-6E, IO-dienoate. The . next Lewis acid-catalyzed step involved formation of the bicyclic decalin ring system, methyl (IR* ,4aS*,8aS*)-2-oxo-5,5,8a-trimethyldecahydronaphthalene-I-carboxylate. The next step was to add a hydroxyl group alpha to the ester, the a-OH being vitally important to the biological activity of warburganal. This step proved to be unsuccessful with the methodology used. A change in tactics was obviously required and initially protection of the ketone as an acetal was attempted. Instead of the expected acetal product, an epimer of the decalin structure above, namely, methyl (IS*,4aS*,8aS*)-2-oxo-5,5,8a-trimethyldecahydronaphthalene-I-carboxylate was isolated. This epimer seems to form under acidic as well as basic conditions and was also isolated from an a-hydroxylation reaction that employed KH and MoOPH. Most of the steps were attempted on model compounds to enable the conditions to be optimized prior to attempting the reaction on the warburganal precursor. It was soon discovered that for reasons as yet unknown, the reactions that worked on the model compounds did not always work on the warburganal precursors, although the model compounds possessed functional groups that best simulated those possessed by warburganal. The progress reported towards the synthesis of warburganal highlights the many difficulties encountered when introducing the requisite functional groups on to the decalin ring skeleton to afford warburganal i. e. the a-hydroxyl and p-aldehyde moieties and the a,p-unsaturated aldehyde. Although the planned synthetic pathway was not entirely successful, the pitfalls encountered are discussed and potential solutions are presented. A number of interesting and unexpected compounds were isolated en route and ideas are discussed that may well culminate in an efficient synthesis of warburganal.Item Reactions and reactivity of allyl and related carbamates.(1997) Mason, Paul Henry.; Emslie, Neville Desmond.Carbamate chemistry has flourished since the 1980's which saw the introduction of the carbamoyl group by Hoppe and co-workers, prominent researchers in this area, as a suitable moiety for the activation and stabilisation of alpha-heterocarbanions which are important intermediates in synthetic organic chemistry. This functionality increases a-CH acidity and stabilises the a-lithiocarbanion thus generated. The versatility of the carbamate group has spawned investigations into the numerous possibilities that exist for the functionalisation of the carbon alpha to the carbamate group. Some of these possibilities were explored in the present work. The direct formation of stable benzylic carbanions alpha to an oxygen atom is not a facile process as such lithiated species are unstable and readily undergo a 1,2-Wittig rearrangement. However, protection of the alcohol as the carbamate enabled functionalisation of both benzylic sites with a variety of electrophiles. Benzyl carbamates were found to react regioselectively with a,~-unsaturated electrophiles to afford either the 1,2- or l,4-addition products. The regioselectivity could be controlled by the presence or absence of a silyl moiety, either a trimethylsilyl or tertbutyldimethylsilyl moiety, attached at the benzylic position, alpha to the carbamate. The reaction of benzyl carbamates with 2-cyclohexen-1-one and 2-butenolide afforded the 1,2-addition adducts in moderate to good yields (25-66%). The isolation of the masked ahydroxy ketone resulting from the opening of the lactone ring on reaction of 2-butenolide with benzyl N,N-diisopropylcarbamate was surprising, as this electrophile is known to behave as an excellent Michael acceptor. The introduction of a silyl moiety at the benzylic position facilitated conjugate addition, yielding the corresponding Michael addition products. A novel cyclisation was observed on reaction of a-silyl benzyl carbamates with methyl acrylate to give the a,y;y-trisubstituted butanolides (y-butyrolactones). The proposed vii mechanism of this reaction is discussed and illustrates the migrational ability of the carbamate functionality. Chiral induction in benzylic systems has only been investigated by a few authors. In the present investigation two possible routes to chiral induction at the benzylic position were investigated using either a (-)-sparteine-mediated transformation or chiral carbamates derived from (L)-proline. (-)-Sparteine mediated transformations were solvent dependent with the best enantiomeric excess of 28% being obtained. The results indicated that racemisation at the benzylic position was faster than reaction with an electrophile. The chiral carbamates were only slightly more successful yielding the a-substituted adducts with diastereoselectiVities of the order of 20-50%. The diastereoselectivities were found to be enhanced by the addition of HMPA which coordinated with the transition state blocking one of the faces to attack by the electrophile. The 1A-addition reaction with 2-butenolide was particulary useful as it allowed the exploration of the synthesis of lignan derivatives from benzyl carbamates. Lignans are secondary plant metabolites and exhibit.a wide range of biological activities. Applying the methodology developed to the synthesis of lignans resulted in the preparation of an arylnaphthalene lignan, in 79%, and the partial synthesis of racemic fargesin, a racemic furofuran lignan. This natural product synthesis highlighted the difficulty in removing the carbamate functionality and re-introducing the alcohol moiety. Thus, hydrolytic cleavage of the benzyl carbamates was investigated using a selection of mineral acids. Depending on the reaction conditions, the products were found to be the corresponding benzyl alkanoates or benzylhalides. The alkanoates are derived from nucleophilic displacement of the initially formed benzyl halide A novel deprotection of a-silyl benzyl carbamates was also observed in which the carbamoyl group was cleaved to afford the a-silyl alkanoates and chlorides without the loss of the silicon moiety.Item Reactions and reactivity of allylic and benzylic carbamates.(1995) Longley, Jeffrey Charles.; Emslie, Neville Desmond.The purpose of this investigation was to study the effect of the carbamate group on the reactions and reactivity of substituted 1,1-diphenylmethane and a,ro-diphenyl allylic compounds. A series of carbamates were prepared and reacted with a variety of electrophiles and nucleophiles. l-(O-N,N-dimethylcarbamoyloxy)-l,l-diphenylmethane (i) reacted with a variety of electrophiles to afford a-substituted carbamate products (H). Reactions of allylic carbamates with electrophiles proceed with substitution at the carbon atom a or y to the carbamate. 1-(O-N,N-diethylcarbamoyloxy)-1,3-diphenyl-2-propene (iii) only reacted with methyl iodide to afford the y-substituted product (iv). Reactions of 1-(O-N,N-diethylcarbamoyloxy)-l ,5-diphenyl-2,4-pentadiene (v) with electrophiles were all unsuccessful. Nucleophilic substitution reactions were performed with carbamates (i), (iii) and (v). No success was achieved in the reactions of (i) with nucleophiles. Carbamates (iii) and (v) reacted with a few oxygen nucleophiles to afford allylic ethers with simultaneous elimination of the carbamate group. Several properties ofterminal-diphenyl carbamates have been revealed: (a) Benzylic carbamate (i) reacted successfully with a variety of electrophiles. Nucleophilic substitution is not favoured with the benzylic carbamate. This indicates that SN2 elimination of the carbamate does not occur in this molecule. (b) Allylic carbamate (iii) only reacts with methyl iodide indicating that the bulk of the diethyl substituents on the carbamate group, the bulk of the incoming electrophile and the size of the phenyl groups are fundamental to the success of reaction. Methylation occurred only at the y-position. (c) Conjugated allylic carbamate (v) did not react with any electrophiles, suggesting that, in addition to the steric factors, the stability offered in the retention of conjugation in the molecule prevented the formation of the electrophilic substitution products. (d) Unsymmetrical allylic carbamates (iii) and (v), in which the carbamate occupies a benzylic position, are more stable than symmetrical allylic carbamates (vi) and (vii) which decompose to the corresponding alcohol. (e) Nucleophilic substitution of (iii) and (v) occurred with SN2' elimination of the carbamate group, the reaction proceeding in a way which faciliates the formation of the most conjugated product possible. Nucleophilic substitution of (iii) with the phenoxide anion resulted in the allyl aryl ether (viii). Several attempts were made to promote the Claisen rearrangement to afford the allylic phenol (ix) but without success. Exploitation of the migrational ability and the leaving group ability of the carbamate moiety were extended to the synthesis of /13-flavene (xi) from allylic alcohol (x). Several attempts were made to synthesise (x) via the Aldol condensation and Grignard reactions. The synthesis of (xi) was hindered by the failure to produce allylic alcohol (x). During the course of these investigations an unexpected decomposition reaction was discovered. The purification by distillation of allylic carbamate (xii) afforded allylic amine (xiii) in quantitative yield. The driving force for the reaction is the intramolecular SN2' elimination of the carbamate with the simultaneous loss of carbon dioxide. This reaction may have scope in the synthesis of allylic amines.Item Reactions and reactivity of naphthyl and benzyl carbamates.(1996) Ramsingh, Bernice Lara Rubenthri.; Emslie, Neville Desmond.; Rahm, Birgit.Item Stereochemical aspects of the Baylis-Hillman reaction.(1992) Khan, Abdullah Ali.; Drewes, Siegfried Ernst.; Emslie, Neville Desmond.Item The synthesis of optically pure 1,3-diols.(1995) Long, Marvin James.; Emslie, Neville Desmond.; Drewes, Siegfried Ernst.Abstract available in pdf.Item Tertiary amine-catalysed Diels-Alder reactions.(1995) Kader, Darryl Dominic.; Emslie, Neville Desmond.; Drewes, Siegfried Ernst.Abstract available in PDF.Item The use of ephedrine and camphor in asymmetric Diels-Alder reactions.(1997) Kriel, Karina Nicole.; Emslie, Neville Desmond.Due to the ever increasing demand for the production of enantiopure drugs and biologically active compounds, the study of asymmetric synthesis and the production of more efficient and cost effective methods of obtaining chiral compounds suggests that there are expanding opportunities for Organic Chemists in this field. Of the broad range of chiral technologies available today for the synthesis of even the most complex multi-centre chiral molecules, the use of chiral auxiliaries continues to remain an important means of obtaining single enantiomer chiral compounds. In this investigation, the imidazolidinone chiral auxiliary (i) was synthesised in order to determine its efficiency and ability to transfer chiral information in Diels-Alder cycloaddition reactions. The products of such reactions are extensively used in the synthesis of natural compounds and pharmaceutical drugs. The synthesis of the imidazolidinone auxiliary is described and mention is made of the fact that the starting materials are cheap and readily available in both enantiomeric forms. The pathway involves only a single reaction that is easily carried out in moderate yields of 60-65%. An adaptation of this auxiliary is the cyclohexyl derivative (ii) which was obtained in a single hydrogenation step of (i) in very high yields (98%). This was compared to the synthesis of the bornane-1O,2-sultam auxiliary (ii). Although the starting materials are also cheap and readily available, there are more reaction steps involved. The synthesis of the imidazolidinone auxiliary proved to be much more simple as well as more time and cost effective. The huge advantage of these auxiliaries is the fact that they are both crystalline which facilitates their purification and that of their derivatives. A possible deficiency of the imidazolidinone auxiliary and the bornane-1O,2-sultam auxiliary was the fact that substitution reaction yields with various a,b-unsaturated acyl chlorides were consistently low (<50%). A major by-product of the acylation reaction was a 'double-adduct' compound that severely affected the reaction yields. This was overcome by employing a new method of acylation developed during the course of this research. It involves the use of DABCO as base with reaction yields between 60 and 98%. In addition to this, reaction conditions were mild and work up procedures simple. The N-acylimidazolidinone auxiliary proved to be extremely successful in Diels-Alder reactions with cyclopentadiene With results equalling those obtained with the well known and highly publicised bornane-10,2-sultam auxiliary. The scope of the N-acylimidazolidinone auxiliary in these reactions included the use of a- and b- substituted dienophiles. Although reactions with a-methyl and b-methyl substituted dienophiles were successful, the auxiliary proved to be unreactive with b-phenyl and b,b-dimethyl substituted dienophiles. The scope of dienes used was extended to include the relatively less reactive isoprene and 2,3-dimethyl-l,3-butadiene. Only the former reacted successfully in Diels-Alder reactions with the N-acylimidazolidinone auxiliary. Crystallinity was imparted to all the products except for the cyclohexyl derivative whose cycloaddition adducts only solidified on standing. The Diels-Alder adducts were successfully cleaved under standard reaction conditions to give products with ee's ranging from 95:5 to 99:1. This investigation also includes the use of the tertiary amine, DABCO, as a catalyst in the Diels-Alder reaction with, specifically, the N-acryloylimidazolidinone chiral auxiliary. Most examples of Diels-Alder reactions involve the use of Lewis acids as a means of improving the rate and selectivity of Diels-Alder reactions. DABCO not only increased the reactivity of the N-acryloylimidazolidinone auxiliary towards cyclopentadiene, but selectivity was also observed. An explanation was put forward as to the mechanism of the reaction as well as to the source of selectivity. Selectivity was much more pronounced in Diels-Alder reactions with the N-acryloylimidazolidinone auxiliary than with the N-acryloylbornane-10,2-sultam auxiliary. It was predicted that DABCO catalysed reactions are amenable to large scale procedures. Due to the fact that the diastereomeric cycloadducts are easily purified by recrystallization or chromatography, and together with the practical advantages and mild reaction conditions this could render the DABCO methodology with the N-acryloylimidazolidinone auxiliary industrially viable.