CARBON ANION CHEMISTRY

Author: MARCOS MONEO CÉSAR.
Year: 2004.
University: BURGOS.
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: Reactions carbolitiación intramolecular provide a route regioespecífica and highly stereoselective for preparing systems carbocíclicos and heterocyclic funcionalizados selectively. Furthermore, the recent development of its version enantioselectiva has significantly increased its potential synthetic. In this context, and given the interest of our research group for the preparation and application of synthetic derivatives organolíticos funcionalizados, has been studied reactivity alil and benzyl o-litioaril ethers, which has allowed, varying only the solvent used or pattern substitution in the anion of departure, the development of new synthetic strategies for the preparation of different types of organic compounds. Thus, the evolution in Et2O, hexane and toluene in the presence of TMEDA of organolíticos derivatives alil o-bromoaril ethers without substituents on the carbon atom position with respect to oxygen or in the position 6 of the aromatic ring leads, so diastereoselectiva, to derivatives ciclopropano through ciclación regioselectiva 5-exo-trig followed by a process of -eliminación in 3-litiometil-2 ,3-dihidrobenzofuranos intermediate. Moreover, this reaction can be carried out enantioselectiva by adding a ligand external enantioméricamente pure, as (-) -esparteína. However, the presence of a replacement in the position on the oxygen atom in the organolítico departure allows halt the process after carbolitiación intramolecular, which has led to a methodology simple, effective and fully diastereoselectiva for the synthesis of trans-2 , 3-dihidrobenzofuranos 2,3-disustituidos. Significantly, when the reaction involved alil 2-litiofenil ethers fortified enantioméricamente, hetero end have the same excess enantiomérico the ether departure. Alternatively, the process -eliminación can be inhibited when the anion of departure presents a replacement at position 6 of the aromatic ring, which has led to the development of a new synthetic route for the preparation of derivatives 2,3-dihidrobenzofurano funcionalizados regioselectivamente at position 3. Moreover, the presence of (-) -esparteína during ciclación allows the preparation enantioselectiva of these hetero, leading to enantiomer (R) - isomer as a majority. On the other hand, alil and benzyl o-litioaril ethers generated in THF initially evolve through a process of anionic exchange for which the lithium atom migrates to the position on the oxygen atom. The -oxianiones generated spontaneously experiencing a regrouping [1.2] Wittig obtained finally alcohols alílicos or Benzyl. The methodology described in the sequence protección-desprotección is generally selectively, and operationally simple. The mechanism of protection implies probably a reaction carbolitiación intermolecular.

Author: Torres Cañabate María de las Mercedes.
Year: 2005.
University: VALENCIA.
Place of defense: Facultad de Química.
Place of preparation: Facultad de Química Universidad de Valencia.

Summary: 1) There have been products of alkylation of dianiones different unsaturated carboxylic acids with halides alílicos. It has been confirmed that although in some cases it gets the adduct regioselectivamente, in general, there are strong deviations to this trend. All products have been separated and identified. 2) The process tandem alquilación-transposición of Cope on dianiones of unsaturated carboxylic acids, as an alternative method for obtaining the regioisomers is not generalizable, and can only be applied in certain cases: a) Those products -alquilación without hidrógenos in position C 2 provide selectively product transposing Cope. B) The products of alkylation with a hydrogen at C-2, under these conditions transposicón of Cope, leading to the goods migration 1.3 hydrogen. In no case notes the product Cope waited. 3) The theoretical studies conducted confirm that the products of alkylation of diendiolatos of unsaturated carboxylic acids with halides alílicos, subjected to heat treatment, generate products with different reorganization depending on the replacement carbon a. There has been an analysis of the thermodynamic stability of the different products can infer that under control thermodynamic conditions, the reactions are controlled by the maximum stabilization systems diénicos present in the reaction adducts. 4) has been optimized conditions reaction dienolatos of carboxylic acids with epoxides using quantities subestequiométricas amine in the generation of the database, making it possible to convert this addendum in a reliable method for obtaining -hidroxiácidos or - lactones, while minimizing the production of secondary. 1.2-epoxihexano (62), as well as analytical methods for the study of asymmetric induction. In the case of the reaction of this acid with 1-bromoetilbenceno (42), there was a 50% excess enantiomérico using (+) -efedrina as amine. 7) In the reaction of dianión acid alkylation Phenylacetic (61) with 1,2-epoxihexano (62) were obtained modest diastereo and enantioselectividades with four employees amines ((R) and (S) -1-bencilamino-2- propanol and (R) and (S) -pirrolidínmetanol). 8) have been synthesized pheromones sexual Trogoderma glabrum (4-hexanolida) and Bredius mandibularis (dodecanolida). The synthesis has been realized in a single step by applying the methodology optimized in this thesis with yields comparable to or better than those already described.

Author: Alemán Lara José Julián.
Year: 2005.
University: AUTÓNOMA DE MADRID.
Place of defense: FacULTAD de Ciencias, U.A.M..
Place of preparation: Universidad Autónoma de Madrid.

Summary: BACKGROUND AND OBJECTIVES OF THE QUESTION PROPOSED This Doctoral thesis is based on the synthesis of various orto-sulfinil bencilcarbaniones and their use as a reagent bencilación asymmetrical face different electrófilos. There is no real background of the work carried out since the bencilación asymmetric not counted until the completion of this thesis, with effective methods to achieve them. DEVELOPMENT OF WORK AND METHODOLOGY The goals are very broad and are reflected in the various chapters of memory in a transparent manner. Most of them related to the synthesis of litiocarbaniones, and the study of their behavior with respect to derivatives imínicos and sililderivados. However, other bencilmetales as bencilestannanos and bencilcobres have also been the subject of study in this dissertation. In Chapter II describes the reactions of -sulfinilcarbaniones with N-sulfinilcetiminas, illustrating how they can be achieved simultaneously controlling the estereoselectividad two chiral centers using a double asymmetric synthesis. This chapter is the real antecedent of the reactions are discussed in the following chapters. Section III describes the reactions of bencilación asymmetric N-sulfiniliminas with ortosulfinil benzyl carbaniones, which is an exercise in double-inspired asymmetric induction in the previous chapter. Chapter IV examines the reactions with iminas without additional chiral centers, which is conceptually more interesting and reveals the extraordinary ability of sulfinilo for funcionalizar positions over long distances. Chapters V and VI dealing with two new processes type Pummerer using bencilestannanos and silicon derivatives, which can obtain alcohol Benzyl enantiomericamente cigars. Chapter 8 describes the reactions of obtaining N-sulfoniliminas and corresponding oxaziridinas. Aunque este capítulo no esta relacionado con el uso de los sulfinilbencilcarbaniones como nucleófilo, la necesidad de disponer de N-sulfoniliminas para ser usadas como electrófilos frente a nuestros carbaniones, obligó a diseñar un método para su síntesis que mejoró sustancialmente todos los indicados en la literatura , which determines their inclusion in the thesis. Finally, Chapter 7 gives an account of the conduct of other reactions discovered in the investigation are true starting points for further study. Reactions bencilación asymmetric with nucleotide, which alcohols bencilicos orto-sulfinilsustituidos behave like synthetic equivalent cation bencilicos chiral and use of bencilcobres in reactions with electrófilos very reactive, have provided spectacular results to be exploited in the future immediately CONTRIBUTIONS FROM NATURE GENERIC OR PILOT have been synthesized different types of amines bencílicas chiral and aminoalcoholes containing two chiral centers in a completely estereocontrolada. We have found two kinds of reactions so far described neck allowing the synthesis of chiral alcohols Benzyl. New methods have been described to improve all existing for the preparation of N-sulfoniliminas (to be joining the series Organic Synthesis) and N-sulfoniloxaziridinas and conceptual aspects have discovered novel whose scope is to be determined such as estereodiferenciación because electronic .

Author: MAGRIZ TASCÓN ANTONIO.
Year: 2005.
University: SEVILLA.
Place of defense: SALON DE ACTOS DEL CENTRO SUPERIOR DE INVESTIGACIONES CIENTÍFICAS ISLA DE LA CARTUJA.
Place of preparation: UNIVERSIDAD DE SEVILLA.

Summary: The reaction of addition 1,2-nucleofílica of organometallic compounds to hidrazonas arising from the (S) - or (R) -1-amino-2-metoximetilpirrolidina (SAMP and RAMP) occur with high diastereoselectividades and yields. This stage is the key step for obtaining various amines enantioméricamente enriched characterized as having a center estereogénico in alpha position. Taken as a whole, the procedure provides a simple route, with a reduced number of stages and on the basis of relevant hidrazonas anentioméricas from SMAP and RAMP. This makes it possible to carry out a screening in vitro and in vivo both enantioméricas structures of large industrial interest. The transfer hydrogenation of benciliminas ketones cyclical 2-sustituidas racémicas using formic acid mixtures / trietilamina as a source of protons and [RuCl (areno) (TsDPEN)] as a catalyst comes with dynamic kinetic resolution to give rise to the corresponding sbenciliminas with configuration on cis and high selectivity. The higher reactivity of the amines respect of ketones in these conditions allows the reaction "One Pot" from the corresponding ketones in the presence of excess alilamina, occur selectively hydrogenation of alilimina formed on the spot. This procedure avoids the need to synthesize iminas, which are often unstable products and difficult to manage and purify. This reaction is the first known example of kinetic resolution links C = N. The developed methodology has been extended to the reduction enantioselectiva ketones racémicas 2-sustituidas through hydrogenation transfer crank dynamic kinetic resolution (DKR), using formic acid mixtures / trietilamina as a source of protons and other conditions alternatives such as transfer phase. Fruit of the reaction are obtained chiral alcohols with two centers estereogénicos with cis configuration and related excesses diastrerómericos of 50-98% and excesses enantioméricos of 60-98%. Finally this method has been generalized to the synthesis estereoslectivas dehalohidrinas 2-sustituidas. Partly due to the high sensitivity of these substrates opposite side reactions such as substitutions and eliminations, achieving reductions with good excesses diastero and enantioméricos and reaction speeds requires reasonable adjustment for each type of substrate, reaction parameters of acidity, dilution, and the use of technical terms and transfer phase. The methodology described in halohidrinas represents the only route overview and enantioselectiva known for the synthesis of halohidrinas neighborhood cis.