STEROIDS CHEMISTRY

Author: AMORÓS AGUILAR MARC.
Year: 2005.
University: RAMÓN LLULL.
Place of defense: ESCUELA TÉCNICA SUPERIOR IQS.
Place of preparation: ESCUELA TÉCNICA SUPERIOR IQS.

Summary: The brasinoesteroides are molecules polihidroxiladas structure esteroidal acting as powerful regulators of plant growth, resulting in increased crop yields and conferring resistance to the plants against adverse environmental factors. There is a proposal on their mechanism of action. It is understood that, as in all joints ligando-receptor, weak non-covalent interactions play a decisive role in the formation of complex hormona-receptor. In an attempt to further bridge for the interactions of hydrogen, has synthesized a series of similar in that amending various hydroxyl present in a brsinoesteroide active polar other features, to explore the role of the various hydroxyl in this type of iteration in the complex lignado-receptor. We have designed a series of strategies for obtaining synthetic analogues brasinoesteroides where amending functionalities present in the anilol or in the side chain: * Similar to changes in the Ring A with two polar functionalities (hidroxiazida, diazida). * Similar to changes in the A ring with a feature polar to C2 or C3 (fluorine, amine, sodium or carbonyl). * Similar changes with the side chain with a polar functionality in C22 or C23 (hydroxyl, sodium or amine), as necessary, for the latter, an extensive work for the identification of compounds. The values of activity analogues synthesized suggest that the hydroxyl ring A, a brasinoesteroide active, serving as aceptores bridge Hydrogen interaction with the receptor, whereas the hydroxyl side chain appear to act as a bridge hydrogen donors .

Author: MOLIST I FUSTE MERTIXELL.
Year: 2006.
University: RAMÓN LLULL.
Place of defense: ESCUELA TECNICA SUPERIOR IQS.
Place of preparation: ESCUELA TECNICA SUPERIOR IQS.

Summary: In the field of brasinosteroides, plant growth promoters was aimed on the one hand, to deepen the knowledge of their interaction with the receiver (where the formation of hydrogen bridges of various hydroxyl seems to play a key role) and, another, similar to obtain cost sintético-actividad. In this regard, it was considered interesting deal with the study of brasinoesteroides androstánicos. Specifically in this thesis, we have developed synthetic strategies for obtaining, in a systematic and efficient, similar androstánicos different side chains. We have studied computationally similarity of all three-dimensional analogues proposed brasinoesteroides assets reference, using alineamentos flexible program with the MOE. The strategies developed to achieve a number of modifications in the ring to see how have allowed the introduction of the functionality 2, 3 -diol is simpler and more efficient than others in advance interesting as 2, 3 -difluor or 2,3-dicetona. We have developed strategies and approaches for the synthesis of similar androstánico best simularía the side chain of brasinolida (brasinoesteroide naturally more active known so far). Anyway, because of the difficulty synthetic acid 3S ,4-dimetil-2R-hidroxipentanoico (side chain) has not achieved the synthesis of similar interest. We have designed, synthesized and evaluated a number of androstanos to study the influence of the terminal hydrophobic portion and the position of the features of the polar side chain, as well as the role of protector of this group in the activity. To validate the methodology SHOP applied previously in the team, has been synthesized and evaluated various brasinoesteroides androstánicos with chain carboxylic acids commercial selected using this methodology. The synthesis and evaluation of the activity of similar androstánicos with different functionalities of carbonyl in the side chain (fluoride, sodium, carbonyl, amine…) as well as that of similar chosen in a systematic way (methodology SHOP) has led to conclude that it is necessary the presence of a bridge functionality giver of hydrogen in this region for a brasinoesteroide expressed as a promoter activity of plant growth.

Author: RODRIGUEZ GOMEZ MIGUEL ANGEL.
Year: 2006.
University: ROVIRA I VIRGILI.
Place of defense: FACULTAT DE QUIMICA.
Place of preparation: UNIVERSITAT ROVIRA I VIRGILI.

Summary: The 2-desoxi and 2,6-didesoxiglicósidos are major structural units that are part of a wide variety of natural products such as tumor (anthracyclines, acids aureólicos, esperamicinas…), antibiotics active against Gram-positive bacteria (eritromicinas, orthosomycins…) ; inhibitors of platelet aggregation (anguciclinas); antiparásitos (avermectinas) or cardiac (digitoxina). Moreover, these carbohydrates are difficult to obtain from natural sources. The stereoselective synthesis of the union glicosídica in 2-desoxioligosacáridos is one of the most complicated challenges in the glycosylation reactions due to the lack of group estereodirector in carbon 2 that can assist in this reaction. This problem can be solved using substituents in the C2 (I SeR, SR) directing the estereoquímica at the stage of glycosylation. These groups can be easily removed once it has performed its glycosylation stereoselective. Others of the most important synthetic intermediates in the synthesis of 2 desoxicarbohidratos (and other sugars) are glycosides 1,2-insaturados, known commonly glicales. The purpose of the work done in this doctoral thesis was the development of new methods of stereoselective synthesis of 2-desoxi and 2.6 didesoxicarbohidratos, as well as synthetic precursors as important as glicales. It has also developed an approach to the synthesis of a drug cardioactivo, digitoxina. Thus, in the introduction discusses the pre-existing methods for synthesizing desoxiglicósidos. In Chapter 1 describes a new procedure to synthesize phenyl 2-desoxi-2-yodo-1-tiopiranósidos and tested its use as giving glicosilo. The key step for obtaining these is giving the ciclación 6-endo of tioalquenoles induced electrófilos iodine regional i stereoselective manner. In chapter 2, 2-desoxi-2-yodopiranósidos summarizes starting tioalquenoles in a proceeding ciclación- glycosylation similar to that described in chapter 1, but a direct and "one-pot." This procedure is used in the synthesis of a 2,6-didesoxiglicósido cholesterol. In chapter 3 are obtained glicales piranósicos of all configurations from furanosas using a sequence of reactions olefinación-ciclación-eliminación. This method is particularly valuable parala synthesis glicales not accessible by other methodologies such as D-allal or D-gulal. Also in this chapter deals with the synthesis of glicales substituted in the C2, such as 2-fenilselenenil or 2-yodoglicales. Finally, in chapter 4, from a common precursor as D-ribonolactona explores a new approach summarizes the digitoxina and other cardiac glycosides as application of the methodology previously synthesized.